Bad cat or not?

Flat out: I drove with cylinder 5 misfiring for 100 miles (possibly a little bit more) and that entire time the rear cat was getting fuel dumped into it causing it to glow lava red. I verified this and as soon as I'd let off the engine speed on the highway especially when I'd come to a stop the coolant temp would soar to the top of the gauge within a matter of seconds. Given this thought and now recently I think I'm getting half the gas mileage I used to now with a new engine and just the fact that the cat glowed for 100 miles do ya'll think its very likely the cat is no longer any good?

I've read where you can test the intake vacuum as an indication of build up of backpressure and of course you can also do the backpressure test itself shoving an air gauge before the cat. In any case I'd rather just do the intake vac test. I guess if I see it fluctuate significantly then its a pretty good guess that the rear cat is toast right?

Your shop should be able to test for back pressure on the cat.
If not, they can most likely recommend a place that can.

I tested the intake vacuum pressure tonight using a vac gauge.

First at idle with no A/C:
The gauge remained in the green (normal motor as it says), but continuously bobbled back and forth from 17.5 to 18.5 in hg vac and sometimes dropping as low as 17in. I did this test in Park. I do not use the word continuously lightly either. It was "constant".

First at idle with A/C:
Gauge immediately dropped to 16 in hg and bobbled from that to 16.5 in hg constantly. As the A/C compressor would kick off and on it would jump back up sometimes up to 18.5 when the compressor went off, then down to 17 when it was on, and then as compressor remained on it would work its way back to bobbling 16-16.5 in hg again.

Each time the radiator cooling fans would turn off the engine again would try to stall and vac pressure would surge up to 18.5 briefly and immediately go back down to the 17.25 - 17.5 range staying there if A/C was off, but eventually always lowering to the 16-16.5 if A/C on.

FYI - Anything below 17 in hg on the gauge is "red zone" aka not right.

Given that we know I've replaced just about every damn thing in this van recently what conclusion could we draw from this test? The gauge says that the "hand should remain steady in green zone" and when I've done this test before in my 3000GT it does in fact remain completely steady at idle as it should be.

Wouldn't constant drops in vacuum pressure constitute a backpressure build up and possible "partially clogged" cat?

How can I test my O2 sensors when they are off if I decide to undertake the task of replacing the Ypipe? Is there a way?

Wiswind - What scangauge "setup" do you use? Brand/model#, connections, config etc..

First off.....I have no clue how to use the vaccum data.

The ScanGauge that I use it this one
http://www.scangauge.com/products/

Mine is the original one....before the II one came out.
I set it in "Gauge" mode.....and then select the parameters that I want to display.
Take note that it will NOT read fuel pressure, Barametric values, or other values that are not monitored on the Windstar OBDII system.

It also does not monitor the fuel trim values.

It is a good, cheap item that is easy to use......and I have found it to be a good investment.
I can leave it laying in the car, which I could not do with a laptop.
One nice feature is that it will do a "freeze frame".....save the various data that you can read in Gauge Mode......at the time that the failure code is set.
So you can see coolant temperature, RPM, speed, engine load, etc.
Not that I would know how to use the data, but a good mechanic might find it useful in diagnosis of the cause of the failure.


As far as the oxygen sensors, I also do not know of a way to test them outside the vehicle.
I would say that if you do not have a failure code, they are good.
The OBDII system monitors the oxygen sensors......and wil give you a code, even if the switching speed gets too slow.
Oxygen sensors were a failure item years ago.....but, at least the ones on our Windstars, are very reliable.
I changed my upstream oxygen sensors at well over 150K miles......and saw NO CHANGE in engine performance and fuel economy.
My engine was running well before and after the change.

Wiswind - About to read your previous post.

When you replaced the ypipe with the walker one were the bolts for where it meets the header pipes fairly easy to reach or did it require removing other stuff to get to those bolts?

First off.....I have no clue how to use the vaccum data.

The ScanGauge that I use it this one
http://www.scangauge.com/products/

Mine is the original one....before the II one came out.
I set it in "Gauge" mode.....and then select the parameters that I want to display.
Take note that it will NOT read fuel pressure, Barametric values, or other values that are not monitored on the Windstar OBDII system.

It also does not monitor the fuel trim values.

It is a good, cheap item that is easy to use......and I have found it to be a good investment.
I can leave it laying in the car, which I could not do with a laptop.
One nice feature is that it will do a "freeze frame".....save the various data that you can read in Gauge Mode......at the time that the failure code is set.
So you can see coolant temperature, RPM, speed, engine load, etc.
Not that I would know how to use the data, but a good mechanic might find it useful in diagnosis of the cause of the failure.


As far as the oxygen sensors, I also do not know of a way to test them outside the vehicle.
I would say that if you do not have a failure code, they are good.
The OBDII system monitors the oxygen sensors......and wil give you a code, even if the switching speed gets too slow.
Oxygen sensors were a failure item years ago.....but, at least the ones on our Windstars, are very reliable.
I changed my upstream oxygen sensors at well over 150K miles......and saw NO CHANGE in engine performance and fuel economy.
My engine was running well before and after the change.

Yeah I'd have a better idea myself on the vac stuff if I could get my service manual CD-ROM to work, but its crapped out on me somehow. CD data is damaged. At least it got me through my engine debacle before giving out. I may be able to make a makeshift CD from files I backed up minus the EVTM information cause those are the only damaged files.

Yeah, I probably will not change out the O2 sensors due to no codes. I really believe its the rear main CAT. I found a way to test the O2 sensors btw after I posted. Its pretty simple if I have them off.

I'm gonna do another intake vac pressure test today with RPMs at 2500. I bought a new manual (OEM paperback) from ebay which I should get shortly. If anyone wants to help they can tell me what the intake vac (inches hg) pressure should be for the 95 Windstar 3.8L. If I keep it at 2500 RPMs (hey I wonder if cruise control will work in park just to hold the engine at rev? Dumb question?) for a minute or so and it doesn't hold steady pressure then I'm gonna be pretty convinced the CAT needs to go.

I have also found a link that shows pictures of what a fouled/melted cat looks like inside vs a good one so that'll help if I get it off.

I would love to have the ScanGaugeII (looked at it just now), but since I have pretty good clues already as to what is going on I'm going to hold off till I get some money coming in.

I think the easiest test would be to monitor intake vac pressure with the ypipe removed (ear plugs probably needed?) and if it holds steady then I know whats up immediately.

I used a deep socket to get to the nuts that are on the exhaust manifold studs.
I soaked them with PBlaster.

I STILL ended up with 1 stud that the nut was frozen on....and the stud unscrewed out of the manifold.
I ended up replacing that stud.
I was only able to locate the studs at the dealership......about $5 each.
They have a different thread for threading into the manifold than for threading the pipe retaining nut on.

There is NO spring on the studs, as some vehicles have.
The flange goes onto the exhaust manifold.....over the studs....and a nut goes on each stud.

I put some high temperature anti-seeze on the threads....never know if you will be back in there someday.

Now, at the back....where the "Y" pipe meets the flex pipe, I needed to come up with bolts.....the OEM "Y" pipe had studs on the back part.....the replacement did not.
New hardware is easier to work with anyhow......

The only thing that I did not like about the replacement is the fact that the top of the converter heat shield is right against the oil pan.

When removing the oxygen sensors......soak the threads with some PBlaster, but ONLY the threads.....don't get any spray or fluids over the body of the oxygen sensor.
The sensor measures the oxygen in the atmosphere.....and in the exhaust.....and generates a voltage based upon the difference.
So....you don't want to seal the external part of the sensor from the atmosphere by getting some fluid into there.

If you look in the picture that I put the link to.....in your other post....you will see that the downstream oxygen sensor is mounted into the rear part of the rear-most catalytic converter.......the metal around the threaded mounting ring is thin....
When I was doing the replacement, I very carefully applied turning only pressure to the sensor, using a oxygen sensor socket......and the mounting ring came right out of the catalytic converter with very little turning pressure.
This would be a problem, had I not been changing the "Y" pipe assembly anyhow!!!!!

Use extreme care in making sure that you get the oxygen sensors plugged into the correct connectors on the vehilce.......it can be a mess trying to track it down if you get that wrong.
So I would label....label....everything....

Thanks again.

Well, I've ordered a back pressure tester this morning. With any luck I'll have it by Saturday or Monday and put all this speculation to rest. I thought about going to the well know muffler place to have it tested, but I feel they would say its bad just to get business. My trusted shop.... well I just don't want to bother them with it really cause since the van sat in their shop for 4 months waiting for the engine debacle to end the last time I brought it back they just told me, "You just need to drive it for a while." so I figure they may say the same thing to me again which is a lil bit of a pickle cause I don't want anyone else touching my vehicles except them.

It will be good to have the gauge anyway as I'd like to test the pressure in my 3000GT as well cause I think I've been running a rich condition for quite some time now.

Anyway, I'll know when I get the gauge.

Would I be safe just using a flare-nut wrench instead of an oxygen sensor socket? I don't even know what an oxygen sensor socket is!??!?

An oxygen sensor socket is just a deep socket with a slot in the side.....so that you can use a socket....and have the wires pass through the slot in the side of the socket.
I got mine at AutoZone.

My sensor came out just fine, except for the rearmost one.....the one that turned out of the metal.....I had to work on it for a while to get the mounting ring off of the oxygen sensor.....without damaging the sensor.
It is still working in the new "Y" pipe to this day.

Now that ya mention it man I think I've seen those sockets before. Just not something you remember cause its used so infrequently.

Hopefully my exhaust pressure tester thingy will arrive today. I probably could've used my fuel/vac pressure gauge and found an adapter to fit the O2 sensor and the gauge hose, but I guess its too late now. lol

Wiswind - Are there any SPECIAL MAGIC BOLTS that must be used for the exhaust or will bolts from Home Depot or other local hardware store be ok? Certain type of metal to use? I know you said you had to go to the dealer for some, but I'm just wondering if I can find them elsewhere if its ok to use any kind I find. I may be lucky though if I do have to replace the ypipe cause the ypipe has recently come off twice due to my engine debacle with ATK recently so I'd think that they should come off pretty good.

Were you able to reach the ypipe bolts to the header pipes from underneath or did you have to loosen the nuts from above the engine first?

I got the bolts at AutoZone....nothing special.
However, the exhaust manifold studs, I had to get at the dealership....they ARE special, I looked for them at AutoZone and Advance Auto (Advance did have exhaust manifold studs.....just not the right size/thread.

I got everything from under the vehicle.....just follow the pipe up to the exhaust manifold.....2 nuts on the studs.
You will need a deep socket to get the nut off of the stud.

Another nut by the transaxle, then the 2 nuts at the front of the flex pipe.
You will need to purchase 2 bolts with nuts to install the new "Y" pipe.
These can be gotten at AutoZone, etc.

If the original exhaust is fine.....I would leave it be.....it is stainless steel.
My original is just fine.
My flex pipe is a bit worn.......I have a new one ($99), but could not get the old one out of the pipe on the front of the muffler......so I left it be untill it really falls apart.

The rest of the exhaust......from the back end of the flex pipe all the way back is 1 unit.....replacement is in parts.
Rock Auto has a nice breakdown of parts under the "information" for the Walker parts.

Wiswind - Should I be using some type of sealant (threads) or ring for reinstalling the O2 sensors?

What do you think makes those exhaust manifold bolts so special? Different kind of metal? Coated with some David Copperfield magic fairy dust? :)

When you get new sensors, there is a small amount of high temperature antiseze on the threads.
So, I would put a small amount of high temperature antiseze on the old sensors that you transfer to the new "Y" pipe.
Be careful to put it only on the threads.....and just a little.

As far as the OEM, they contain more "stuff" and work better, from what I have read.
It took quite a while for the OBDII system to finish the drive cycle test.....as the downstream oxygen sensors are the last thing to finish.

My Walker replacement has been doing fine, and I have passed 2 emission tests with it (Wisconsin emission tests every other year).

I replaced mine because the ceramic honeycomb was broken inside one of the catalytic converters.....Otherwise they were fine.

I have obtained the back-pressure tester Tuesday and tomorrow will be the first chance I have to test the exhaust pressure. I will be following instructions I found somewhere to do this correctly.

Also, note I confirmed today at 212 miles on the trip odometer after filling up with 19.197 gallons of gas that I am getting a WHOPPING 11 MPG. I TOLD THOSE SUCKERS AT MY TRUSTED SHOP IT DID NOT FEEL LIKE IT PULLED AS HARD AS IT USED TO! THOUGH ITS A VAN N ALL I KNEW IT WASN'T GIVING ME THE POWER IT USED TO. AND THEN THEY SAID JUST DRIVE IT A LITTLE MORE AND BREAK IT IN!?!?!??!)@(*$)*_+!+_ aRRGGghhHHH !!! I mean do you have to break in EVERY new car you buy till it gets you better gas mileage? I DO NOT THINK SO. NEW ENGINE should mean BETTER gas mileage to BOOT as far as I'm concerned.

Anyway, I'll prove it tomorrow and I will be very very surprised if I am wrong about the CAT needing replacement at this point.

Searcherr, could you tell me where you bought, what brand, how much, etc. your back pressure tester and what all it can do and how, etc,
Thanks

i'd be interested to know about this too. Please elaborate!

Does it run bad, or lose power? Pulling a O2 sensor out of the exhaust and driving it gain more power, then its clogged up. No change still doesnt mean its good, only a Emissions test will provide that info if its working or not.

Pulling an upstream O2 sensor to look for a performance change due to a plugged cat sounds like a good idea to me.

http://www.amazon.com/gp/product/B000BHJ4UY - thats the pressure tester I got.

I'm in a hurry so I can't go into much detail, but I did the pressure test yesterday on the cat I thought I saw glowing. I used the O2 sensor hole just before it (rear most cat). IDLE and 2500 RPMs test showing normal in green range. Needle was bouncing around the entire time from the turbulent air I suppose, but it stayed in the green and near ZERO backpressure as it should be. I've got to check the test instructions to make sure I did it right, but I think I did and now I'm pissed cause this means there is some other odd problem as to why I'm only getting about 10-11 MPG !!!!!!! AAAAAAAAAAAAAAAAAAAAHHHHHHHHH !!!!!!!!! I'm going to strangle myself ! lol

I've been following this post as many others have but I haven't heard mention of the infamous 171/174 repair. I don't know if you've done it, likely you have, but FWIW, I noticed a huge increase in fuel economy when I did this. Interestingly, I didn't have the 171/174 code come up.

So, if your back pressure is ok, and it seems it is, and you haven't done the repair, that'd be my next step.

Piper

The P0171/P0174 repair that is refered to in the sticky is for 1999 and newer windstars only.
The isolator issue for the upper intake manifold bolts does not apply to the older design upper intake manifold.
HOWEVER, our older units are just as prone to other vaccum leaks.
I certainly hope that searcherr's upper intake manifold is in good shape....as he just had the remanufactured engine installed.
However, there are a lot of other opportunities for a vaccum leak.....as all the other vaccum lines are old.

I wonder it the pressure ahead of the catalytic converter is staying as nice when it is warmed up....and driving down the road at higher RPM AND engine load.....as this is when the problem seems to be happening.

I've been following this post as many others have but I haven't heard mention of the infamous 171/174 repair. I don't know if you've done it, likely you have, but FWIW, I noticed a huge increase in fuel economy when I did this. Interestingly, I didn't have the 171/174 code come up.

So, if your back pressure is ok, and it seems it is, and you haven't done the repair, that'd be my next step.

Piper

I guess that means code "171 or 174". I think I've heard/read of it on here a few times, but no I have not done the repair related to it. At this point I was thinking to replace the CCRM cause its the original one, but I am still leaning towards backpressure because I don't believe I let the vehicle get hot enough to have the cats working at operating or higher temp. I still have the gauge hooked up so I'm about to go test this out again this time at full temp.

Other than this 171/174 thing or the CCRM I'm really going to be at a loss because I have damn near replaced everything else. I was thinking "spark plug gap" maybe, but those plugs were supposed to be pregapped to .054" and are Autolite Iridiums -the good stuff- supposedly. Anyone had problems with those kinds of plugs in our engines?

The P0171/P0174 repair that is refered to in the sticky is for 1999 and newer windstars only.
The isolator issue for the upper intake manifold bolts does not apply to the older design upper intake manifold.
HOWEVER, our older units are just as prone to other vaccum leaks.
I certainly hope that searcherr's upper intake manifold is in good shape....as he just had the remanufactured engine installed.
However, there are a lot of other opportunities for a vaccum leak.....as all the other vaccum lines are old.

I wonder it the pressure ahead of the catalytic converter is staying as nice when it is warmed up....and driving down the road at higher RPM AND engine load.....as this is when the problem seems to be happening.

I guess yer right wiswind. I should go drive around with the backpressure gauge installed huh? That makes damn good sense to me since its happening on the road and at Idle after I've driven it for a little bit.

Thanks for letting me know I'm exempt from the 171/174 stuff before I went and wasted a bunch of time researching it. lol

Vacuum lines - My shop did a thorough inspection 2-3 times of stuff like that (recommended me replacing my front brake lines for 1). I was looking at the manifold and the only vacuum line I can identify is just the 1 big one at your front right top (if you are facing the engine bay from the front). Thats where I plugged in the vac gauge to check intake vac pressure. It breaks off from what looks like 3 different lines after that, but the intake vac pressure test failed at idle and with A/C on especially and if that is in fact the only line out for vacuum then it would seem that I redirected any possible vac leaks to the intake pressure tester gauge (which I know is sealed) and yet the vacuum was still not satisfactory. I need to verify this though in the Ford manual as I've yet to open the paper one I've received recently.

Road Test and Park Test 2 results

I let the engine heat up. Slow trip in the neighborhood. I wasn't gonna take it out on the road for fear my duck taping of the backpressure hose was gonna come loose and the tire would take it away for good, but I did it anyway.

At idle the pressure seems fine with the needle fluctuating rapidly at or near ZERO psi.

At 2500 RPMs in Park the pressure remains in the green zone of the gauge and near zero sometimes fluttering up to 1psi to 1 1/4 (1.25) psi.

On Driving at 2500 RPMs steady, pressure remains 1.25 psi and sometimes on slow acceleration gets up to 2.5 psi.

On Acceleration (my own test) with RPMs 2500 or more pressure does jump up to the red zone above 3 psi, but usually with higher RPMs than 2500. I have no way of knowing for sure if this is a valid test, but I did notice it.

NOTE: When the van would try to stall "consistently" at hot idle EVERY SINGLE TIME it was at the very MOMENT when the radiator cooling fans turned off and sometimes it would try to stall harder than others BUT BUT BUT as I sat and watched the back-pressure gauge still hooked up during the attempted "stalls" at IDLE RPM the backpressure was REMAINING AT ZERO. Does this rule out a bad cat? NOT SURE, BUT it may rule out a "clogged cat". The cat could still be bad, but not clogging. Though still I'm not entirely sure.

One thing I do know (that is normal behavior) though is when a sharp acceleration takes place you loose intake manifold vacuum for an instant and then it comes back. If you think about it this drop in intake vacuum probably represents a rapid exit of air and it would make sense to me that would show as a slight pressure increase in the exhaust HOWEVER I DO NOT KNOW FOR SURE. Documentation out there is very scarce on this matter.

My trusted shop told me though that there should be ZERO back pressure in the exhaust, but did not state "WHEN" and the "WHEN" I have in question is during acceleration because thats the only time back-pressure rose to the highest mark of the green acceptable zone on the gauge and also went into the red zone consistently on sharp acceleration.

INFRARED / LASER POINTER THERMOMETER TESTING
Well low and behold of all things my SISTER just so happened to have one of these. I took advantage of it and probed around underneath the van while it was running at idle ONLY. Don't ask me why she has one of these. We're a "unique" family. LOL

Results of the temperature testing:

*From front to rear in direction of exhaust air flow

Engine Block itself: 191 - 215 F - It would get as hot as 215 at times though usually about 209 and then the cooling fans would kick on. Most of the time though it ran from 202 - 215 F at idle.

Front Bank Exhaust Header: 280 - 315 F

Front Cat Inlet: 330-360 F
Front Cat Outlet: -later-

Rear Cat Inlet: 373 - 441 (this is the one I thought/thinks was/is bad)
Rear Cat Outlet: -later-

YPipe Meets Flex Pipe: 345
1st Flex joint: 210
Mid flex pipe: 277
2nd Flex joint: 164

Flex meets Muffler (square thing): 275

Muffler to resonator pipe (the resonator actually looks like a typical muffler to me rather than that square thing): 216

Muffler: 161

Pipe after muffler: 139

Now what does all this stuff tell us?Unfortunately it may still not be enough to say the cat is in good shape, but it gives us clues. The rear cat is obviously running hotter that the front one and since thats the one I saw glowing red when I had the misfire it makes me think its partially damaged/melted inside. I was hoping for ZERO pressure at all RPMs and I didn't get that, however the gauge indicates the majority of the time I was in the safe zone for back pressure except "during acceleration" vs "at 1 given RPM" sticking close to zero psi. I still feel the engine is running hot and I topped off the coolant weeks back to the "FULL COLD" line in the reservoir. I also checked and filled the coolant level in the radiator itself to fill it to the top, but I've forgotten how to "burp the coolant" system and perhaps it needs this since it seems to be running hotter than usual.

If people could post back with what temps they run at idle that would be helpful.

The measurements at the flex pipe to the muffler confuse me, but perhaps could be due to thickness of metal at the different points I measured. The mid-flex pipe section seems very close to the muffler casing temperature near its inlet so I'm inclined to thinking that the flexy areas of that pipe must be several layers thicker than the mid section of it so not as much heat gets to the outside at the flex spots than the solid surface spots. If my theory is true then the temperature is decreasing as it should all the way back to the exhaust tip and the only eyebrow raiser here would be the Rear cat temps. I later saw online that I should've measured the outlet temps of the cats too cause that apparently is an indicator of how well the cat is doing and/or if you are running lean/rich on that particular bank. I also must test the front bank pre-cat back-pressure to have a point of comparison to the one I believe to be bad. If the pressure readings are considerably less so on acceleration and overall than the rear cat then I'll feel better about having determined the rear cat has really gone bad. Still, I cannot forget that as the engine tried to stall several times there was no back-pressure reading above ZERO at idle.

One hittin the gas and one at the tail pipe. If you can feel exhaust 10 12inches away from the outlet its not clogged. another test is to start and idle. Hold your hand over the tail pipe and cover the outlet. If it doesnt stall right away and pushes your hand off.. its all good.
A clogged cat plus your hand will kill your engine in less then a second. These are quick tests done back in the day that would give you a quick idea.
The harder thing is to see if the cat is working. AS you need a emis tester.

I've never gotten a half clogged cat as of yet..
On Dodge tho, Most would spit out peices of the cat after it was glowing red hot from a Head gaskets, Leaks, injector problems and Air pump problems. It would unweld itself just from the heat alone..

Also, any noise rattling in ther is another sign. Shake the cats or soft rubber hammer.

Oh, If your engine is running crappy you will get a hot cat anyway. Just because one is hotter doesnt mean its clogged, but means its working.. If the temp is way off the scale, YES. but your numbers arnt that far away from each other. Cats need the heat to work.

1psi normal average idle
3psi at 2000 or 3000 is to much.. this isnt a DRIVE down the road test, just a parked RPM test..

keep in mind too, the rear cat is laying flat under the car collecting more heat..

Id get a emission test done and see if they are working. If it fails you know.. Your 1psi looks perfect

History on CAts.. Most people dont even notice there cats are clogging since it does it over a long period of time. Loss of power isnt noticed. Cats arnt the easiest thing to clog up these days. They are built much better then the old days. The cats made of BBs or balls were the worst!

I tested the front cat at the pre-cat O2 for back-pressure and it tested to ZERO again. At this point I'm steamin cause if it was the clogged cat at least I could point my finger at it. Now I haven't a damn clue. New Jasper engine, all new stuff, new tranny (20k ago), and a crap load of other new stuff as I tried to hit the stuff known to wear or go bad.

Could the cat still be causing bad fuel economy if its just "no good" as opposed to "clogged"?

Could the CCRM cause horrible fuel economy?

Could I have a bad O2 sensor without it giving a code?

*Word of advice to anyone who buy's the back-pressure gauge I linked to or any other with a rubber gasket on the threaded side. REMOVE THE RUBBER GASKETS BEFORE DOING THE TEST! I DID NOT and they melted and there was an inner one for smaller O2 sensors that I now know was taken into the rear cat during the test driving. I'm also wondering if since the bigger rubber gasket melted if that space that was occupied by it before it got hot caused a pressure leak during the test (although I don't think so) thereby screwing the test up.

I could not get the O2 sensor to thread back into the rear pre-cat hole afterwards because of the melted rubber gasket and I didn't realize what was going on until much cursing.

In any case I'm aborting mission and sending it back yet again to the shop. I'll tell'em to test the exhaust emissions and see whats up. At least I have already picked out a ypipe if I need a new one.

A bad O2 or Weak o2 can change your fuel spray time, timed width etc. affecting your MPG.. NO codes of a bad O2 is common.
A slow O2 is more common as it still works but is very so to respond back with a voltage. Simple Monitor Scanner or a Volt Ohm meter can show you your O2 peaks and low spread.

BTW - Forgot to mention that earlier when I was doing the testing with the backpressure stuff I noticed a small puddle of water about 1 foot wide from the tailpipe. It is DRY air today (not even over 30% humidity) and was about 55F outside at the time of the test. The van was tilted on an incline though. I wonder if this is normal exhaust moisture build-up that just started coming out cause I had it on incline? or is this an indicator of something?

Why would a bad or slow O2 cause the van to almost stall ONLY when the cooling fans kick OFF?

Perhaps this is my problem (bad O2) in the rear where the cat was glowing.... the cat survived, but the O2's didn't ????? Note: O2 pre-cat rear looked black. O2 pre-cat front looked BONE WHITE - now I'm sure most of this build-up was from the previous engine, but doesn't white mean lean and black mean rich?

BTW - Forgot to mention that earlier when I was doing the testing with the backpressure stuff I noticed a small puddle of water about 1 foot wide from the tailpipe. It is DRY air today (not even over 30% humidity) and was about 55F outside at the time of the test. The van was tilted on an incline though. I wonder if this is normal exhaust moisture build-up that just started coming out cause I had it on incline? or is this an indicator of something?

Why would a bad or slow O2 cause the van to almost stall ONLY when the cooling fans kick OFF?

Perhaps this is my problem (bad O2) in the rear where the cat was glowing.... the cat survived, but the O2's didn't ????? Note: O2 pre-cat rear looked black. O2 pre-cat front looked BONE WHITE - now I'm sure most of this build-up was from the previous engine, but doesn't white mean lean and black mean rich?
The White/brown vs black isnt always true.. Once black theres no going back to white.. As for your O2, YES that high rich condition could kill your O2 and even clogged its little vents. exsessive Heat can also kill it.

Stalling after fans.. I did notice on my van that after I have reset my pcm New Battery Installed, I was checking my voltage peaks with lights on AC and heater blowers on high. When I turned them Off the Idle dropped very low to almost nothing and popped back up. The Idle control valve does all that work.. Load on the Alternator, then No Load Increase in RPM, PCM see that increase lowers the Idle, But lowers it to much and corrects itself.
Check your voltages first Charging battery grounds.
Then go for a ride and relearn your PCM.

About your WATER spot, Mine loves to make a spot when Idling alot too.. "Getting Trans fluid WARM idling for awhile will leave a puddle..

I think its 100miles to relearn a PCM.. If it still stalling after fans, I would reset the PCM again and the first startup, Let it run ONE min idling. Then shift into each gear R D 2 1 then P.. Then go drive it.

You should measure the exhaust pressures on the other side for something to compare to. So far, the pressures on the suspect side under the conditions you tested seem very reasonable enough to conclude there is no appreciable clogging. The temperature comparison is more interesting and certainly worthy of speculation. I would think the O2 sensors would be telling you if the cat is not working. Also an emmission test should reveal anything. As to your engine temp, I think you have already proven to yourself that it isn't out of line with the temps you got with the laser thermometer. I would even go so far to say that it is doing an excellent job of maintaining the proper temp. If it continues to bother you, check the sending unit, replace it if it is the original, especially since your engine had overheated. Do you have a new or original radiator? What temp thermostat did you have before and what do you have now? OEM is 190 deg F. Your flex pipe has a wire sheath over it, that acts both as an insulator and a radiator causing it and nearby connections to be cooler. The actual flex pipe inside the sheath will be of similar temp to the adjoining pipe. The O2s in my mind would be suspect having eliminated all else. I don't recall what caused your one cat to go red, but it would make me suspicious that the O2s in that pipe are clogged or shot. Besides what's replacing one more part? Have you considered replacing the seats?:)

You should measure the exhaust pressures on the other side for something to compare to. So far, the pressures on the suspect side under the conditions you tested seem very reasonable enough to conclude there is no appreciable clogging. The temperature comparison is more interesting and certainly worthy of speculation. I would think the O2 sensors would be telling you if the cat is not working. Also an emmission test should reveal anything. As to your engine temp, I think you have already proven to yourself that it isn't out of line with the temps you got with the laser thermometer. I would even go so far to say that it is doing an excellent job of maintaining the proper temp. If it continues to bother you, check the sending unit, replace it if it is the original, especially since your engine had overheated. Do you have a new or original radiator? What temp thermostat did you have before and what do you have now? OEM is 190 deg F. Your flex pipe has a wire sheath over it, that acts both as an insulator and a radiator causing it and nearby connections to be cooler. The actual flex pipe inside the sheath will be of similar temp to the adjoining pipe. The O2s in my mind would be suspect having eliminated all else. I don't recall what caused your one cat to go red, but it would make me suspicious that the O2s in that pipe are clogged or shot. Besides what's replacing one more part? Have you considered replacing the seats?:)

When you say other side you mean the front pre-cat right? I have only tested the pre-cat O2's for front and rear banks. I have NOT tested the post-cat O2's at all cause I figured it was pointless (right?). I mean if there is going to be a clog testing furtherest up the exhaust pipe on each exhaust manifold would show it no matter where the clog is right?

Could the temperature sending unit also be called temperature switch? or are you referring to the engine temperature sensor? Looking it all up there's a coolant temp sensor, temp switch, and engine temp sending unit on Autozone's web site.

Radiator is new. Had to be. Old one cracked during the overheat.

I got the thermostat from NAPA which claimed that OEM was 195 F. RockAuto.com confirms it as well. And somewhere in my notes I have saved I wrote: OE specified temp 192 - 195. So I'm probably alright. I just would feel better if I would've gotten the OE Ford thermostat in general now that i'm seeing some strange heat trouble. It just never used to bob on up to the M and back down to the A like it does now. This COULD be due to the rear cat being EVERY SO SLIGHTLY partially clogged since I observed temps higher in it than the front one consistently. I know the hotter a cat is shows its working, but this was at idle and it would seem logical that both cats temp should be within about 20-30F difference.
BUT BUT BUT for the thermostat OE temp - I just looked up on Oreilly's web site and they list 192F as OE TEMP yet on the same page they sell a Motorcraft brand RT1152 190F/88C thermostat. So this causes me to go look at Motorcraft.com for specific OE info and sure enough yer right. It says 190F/88C and lists the same part number RT1152. So in other words I've got a thermostat in there that is rated 5F more than stock OE and I guess this would explain the slightly higher temp rise before the cooling fans kick on.

Misfiring on Cylinder 5 for about 120 miles caused the cat to glow red. I had no choice, but to drive it home that way leaving my trailer behind.

Could a failing fuel pump cause bad MPG or would that just suddenly STOP working altogether causing much worse than I'm experiencing?

O2's - I am leaning towards this now too. It would make the most sense to me at this point and I'm hoping the only one I'd have to replace is the rear pre-cat O2 and that the rear post-cat O2 survived the onslaught of fuel that caused the cat to glow.

Still, I'm itching even though I don't have the money to replace the whole damn setup. All O2's, Ypipe, and rest of the exhaust as well. I want a little more HP and MPG for all that I've put into it.

Until tomorrow.

A failing fuel pump-

Your running down the road and its just gives up. As it cools 5 or 10 mins it works again and starts your engine. Then gives up again.

Sometimes once they are stuck, you would have to beat on the fuel tank to get them pump again.

They either work, or not. Never had a pump give Half or Over pressured the system.. EVER..

You do have a regulator on your fuel rail tho. Chrome piece with the Vac line on it. That controls how much fuel pressure is in the rail.

Wiswind - Are these the manifold to Ypipe bolts you were talking about only being able to locate at the dealer?

http://www.autozone.com/R,APP1147872/vehicleId,1995201/initialAction,partProductDetail/store,3005/partType,01267/shopping/partProductDetail.htm

I just happened to accidentally stumble on them on Autozone's web site.

The original ones have NO springs.....I saw several places that listed the spring ones....but that is not what we have.

Thing is.....in order to match up the threads......the ones that screw into the manifold.....which ARE completely different from the ones on the end that the nut threads onto to hold the "Y" pipe.......you would have to have the stud in your hand.
I am just not comfortable with auto part store listings when they list a contraption like you found for our vehicle.......and I ran across the same thing on several sites.

Some of the confusion about the thermostat..... there is a temperature rating for the thermostat to START opening.....and another temperature rating for the thermostat to be FULLY open.

I think EPA rating for our windstars was about 17/23 for the 3.8L motor...
I just took a trip....and got 22+, 23+ and 23+ each on 3 tanks.
That was with the cruise control set at 65mph.....watching most traffic pass me......
The vehicles that I passed were mostly semi trucks.....I seemed to be going at about the same speed as them...within a couple mph.......and small economy vehicles.
The trucks have slowed down to save fuel.
Once you get up over 65mph......fuel economy goes into the tank.
Cruise control really helps the fuel economy.

In town....fuel economy bad.......depending upon how much you can cruise along at a steady speed........

Like you....I use fuel economy as an indicator of how well my vehicle is running.......and I look for an average over several tanks.
But.....as mentioned......in town driving is super variable........

I wonder if I can just reuse the exhaust manifold to Ypipe bolts cause recently the shop sure did. I mean those things are freakin RUSTY lookin, but they are on there holding it up.

EDIT: AH HA! - This looks like what you have been describing: http://info.rockauto.com/RB/Detail2noTip.html?http://www.dormanproducts.com/images/items/hwrap1/03132.jpg

Yea Nea?

You only need a new one if something happens to one of the 4 original ones.
A "normal" repair would not need them.
It is just one of those things that "can" go wrong.....and if it does.....you know where to go to get the part.....without having to shop around.

Reg GAS 2.94 gallon
DES 3.99 gallon
Spring its suppost to get worst.. I fixed my IMRC awhile ago "Clips 6.64 each HAHA Local Dealer rape", improved fuel mileage. get around 16 city. 22 highway. Not hooked IMRC below 15mpg

I was suggesting to measure the temperatures and backpressures on the front and back bank pipes thinking that would be a way to make a reasonable comparison to help decide the relative condition of your suspect cat. I would expect the comparison to be similiar enough even if there is some configuration differences. Taking the reading at the pre cat O2 locations makes sense. At this point, I'd be curious to know the readings at all available locations. If pre cat is reasonable, than post cat reading isn't necessary as you said, but it would give you an idea of the pressure drop caused by the cat. Is there a pre cat that may be clogged?

I definitely would expect there to be a greater backpressure upstream of the cat when you are hard accelerating. Can't fight physics, more specifically fluid dynamics. More and faster flow creates more resistance to flow, just like it's harder to hold your hand to your tailpipe at a high rpm vs. at idle.

Let's see, the dash temp guage gets its signal from the engine coolant temp sending unit which uses a single wire connection, strangely that looks like the AZ temp switch, strange they don't know what it's supposed to be called. (That can be a real problem because Ford uses that name for another coolant sensor switch, a real switch this time!!!) The engine coolant temp sensor (ECT) is a two wire unit that supplies a signal to the powertrain control module (PCM) for fuel trim and operating the radiator fans. AZ calls it an engine and a coolant temp sensor.

Your cooling fan will kick on at around 200 - 220 degF irregardless of anything else because it is controlled by the ECT and PCM. Once the engine is at normal operationg temperature, the thermostat will either stay open all the time or it will cycle open and closed due to the cycling of the cooling fan and passive cooling through the radiator. So your temp gauge will top out near the cut in temperature of your ECT and should bottom out at the ECT cutout temp. Yes, it is possible that your tstat keeps the engine hotter before it lets the coolant to the radiator, but once the passive cooling of the radiator is insufficient, the ECT will bring on the rad fan. At present, I would not rush to replace the tstat you have. Why not play some more with your laser therm? My tstat spec says opening temp 188 - 195, and fully open temp 208 - 215 deg F.

On your O2s on the suspect cat, if the pre is suspect, I'd expect to need to do both. If one was exposed to whatever ruined it, then both. At the very least, I would be suspicious of its condition. They can be tested. If they are not right, I sure would expect CEL codes. In the face of that, if the O2s are not functioning properly, they can give incorrect information to the PCM that would have it incorrectly control the air and fuel inputs.

I think I about covered it all, if not let me know.

F__k it. I know for sure that cat was glowing red due to dumping of unburned gas. I've got a new engine and just about every other damn thing is new too. I'm gonna replace all 4 oxygen sensors today with BOSCH part # 15716 - These are OEM direct fit and the same BRAND used by Ford. The Ford and Bosch names are on the O2 Sensors so I figure I'm good to go with these. With any damn luck she'll start acting right after I replace them.

I thought only these sorts of ongoing problems happened to me. I feel for ya man. I'm gonna be pleased when it's finally sorted out, I can't imagine how you'll feel! At least you'll have an (almost) brand new van!

I have all 4 O2 sensors and I didn't install cause I ate and was full. lol - Then while eating I got to thinking about that hi-flow magnaflow ypipe I could buy and how easy it would be to dump all 4 O2's in that pipe first and then just bolt the pipe on with all the sensors ready to go.

I thought only these sorts of ongoing problems happened to me. I feel for ya man. I'm gonna be pleased when it's finally sorted out, I can't imagine how you'll feel! At least you'll have an (almost) brand new van!

Ongoing. Thats a great word. Sometimes I wonder if I wasn't so detailed and so aware of things if I'd have hardly any problems at all. Sometimes too much proactive nature causes problems to arise that would've otherwise been gone unnoticed, fine left alone or if not FINE just "ok" enough to get by.

I haven't even said what I noticed when I was under the van the other day and did the backpressure tests. There is a missing transmission pan bolt and fluid is dripping out of at least 1 of the bolts that is still in there. I went by Ford today and when I said "1995" everyone went "wooooooooOhhhhhh" and instead of looking stuff up in the manual or computer they opened the SPECIAL MAGIC DRAWER of "extra" (lol) parts and started looking for a bolt that looked like it MIGHT FIT. They gave me 2 bolts and actually I think 1 of them is going to work cause it started to thread in nicely and then stopped. I did this by hand to be sure I didn't mess anything up and looked at the bolt threads afterwards and I guess it was in that MAGIC DRAWER because there is 1 thread on it that looks like it might be smOOshed a little bit. The bolts on my pan have "98 D" on the face of their heads. Coincidentally the bolt that started to thread has "98 E" or "E 98" on it (can't remember what order). I'm gonna see if I can't file that thread back into shape and try it again. Then I'm gonna criss-cross hand torque it all down and hope the leak stops.

I'd be VERY reluctant to install the Y pipe with the O2s installed. Whenever I've done exhaust work, there is ALWAYS a bunch of bumping around to get it fitted and bolted up. It only takes one bump to have regrets. Those things aren't cheap and I have gotten the impression they are are sensitive and somewhat fragile. They should be fairly easy to install as you have new holes and no rust. Be sure to add anti sieze lub and use 10% less torque than recommended if you do.

Many oxygen sensors come with some antisieze already on the threads....so if it is already there.....don't add more.......
For what it is worth.....I did replace my upstream oxygen sensors.....figuring that the switching speed slows down over time....and 1 had slight green stains from my lower intake manifold gasket leaking coolant......(replaced sensors after repair)....
What I found was that I got no change in performance or fuel economy.....the vehicle was running just fine before and after the replacement.
So, I conclude that the oxygen sensors on the windstar are pretty reliable.
I would recommend that the upstream sensors be replaced as a pair.....so that you have identical switching charactoristics on both banks of cylinders.

The downstream sensors don't need to switch as fast.....and are only used to monitor the catalytic converter.....so no performance or economy gain will be gotten from replacing them, unless they are defective.

I have to be honest Wiswind - when I was in Autozone yesterday the only thing that was keeping me from buying the O2 sensors (which I ultimately did do) was having read somewhere that your O2 sensor replacement did NOTHING for you. However knowing that cat was full of gas and glowing and that I'm having horrible fuel econ and the engine tries to stall at idle AND given there is virtually nothing left to replace I figure I'll give this a try.

Is there a procedure for cleaning O2 sensors? I plan to keep the ones I take off and test them using a procedure I found online. If I'm patient enough I may even test them before installing the new ones, but I dunno... my patience is very thin since this ordeal has been going on for 5 f'in months now.

The burning question I have is what do you do to have so much spare money and time to keep adding more and more to your evergrowing Winnie transplant project, because I want that too!?!

The burning question I have is what do you do to have so much spare money and time to keep adding more and more to your evergrowing Winnie transplant project, because I want that too!?!
:) - I'm in IT. I can do just about "all of it" when it comes to computers and I'm a jack of all trades to boot. Though I am in debt now again where I was not before. I committed to not using the credit cards ever again once I became debt free, but I haven't been able to avoid them completely. I'm actually not working right now (there's all the time I have) pending getting the van AND the car right before I go back out to work or before I start my own business which is more likely than me going back to corporate work. I will probably supplement my business startup with a part-time job soon too and of course living at mom/dad's since this debacle started has helped a great deal. I have my ex-gf to thank for me dealing with a new engine this soon and then also to thank for me living back at home rather than in the apartment she's enjoying that I am stuck paying half the lease for and I can't even live there!

My car is another story. I've been working on it since Katrina "ever so slowly" and it was a low priority as the van was getting me around just fine and I had stockpiled all the parts I needed for my car when I was working. I also "fit better" in the van currently too. lol - I got help with the van from my father after the breakdown in Oct 2007 since it was very unexpected, but I have put in probably 1/3 (at this point) of my own money/credit too. The van sees the shop more than my car cause I'd rather work on my car than the van, though I'll be doing this exhaust stuff myself if I can help it. Overall I prefer not to spend money on costly repairs, but I am about "completing" the job as it should be completed to make things right ruling out everything along the way. As I asked my parents advice they've both already spoken their mind that everything that was "possibly" damaged should be made NEW again and while its an old fashioned way of doing things it is EFFECTIVE and more often than not faster than troubleshooting for WEEKS or MONTHS in this case. If I take all the guess work and analytical baloney out of the equation and just stick to knowing that I saw the cat glowing red and I have shi__y MPG it makes the most sense that its the O2 sensor or an exhaust blockage. I am going to be curious to test for backpressure on "acceleration" on the highway after I get everything installed to see if I pass the 3 psi redline on the gauge again. If I do not then I will conclude that my new setup DOES actually flow better than stock setup and maybe even be happy and smile.

I'm just worried about all the rust flakes and whatever else will fall in my face when I'm down there taking off the ypipe. It looks to me as if my trusted shop left the ypipe attached to the exhaust manifolds when they did the engine work and sliced the mid-pipe with a torch. The bolts and flange where they meet just do not look like they were tampered with at all. Perhaps I'm wrong, but thats what it looks like they did. I was hoping they'd removed the ypipe from the exhaust manifolds cause that would make it that much easier for me to deal with it myself.

Sometimes you can remove exhaust manas and remove engine. Its not uncommon. Some remove intake, heads then pull the small block out. Ive even seen pulling the whole subframe down with the exhaust still all connected. The less exhaust work or removal, the less time messing with rust or broken exhaust pieces.

Wear goggles while working on the exhaust.......trust me.....glasses are not enough.

I think that you will find the Walker "direct fit" unit to give you good service for the money.
Remember.....you have a "dual exhaust" at that point.....each converter only has 3 cylinders blowing into it.
I also recommend leaving the rest of the exhaust system in place, unless it is for sure defective right now.
This is the approach that will give you the best value and service for your hard earned money.

Remember to support the flex pipe....
The "cat back" part of the exhaust system can be replaced at a later date....in the unlikely event that should become necessary.....without disrupting the "Y" pipe at all.
The flex pipe can be replaced on its own....
The rest of the "cat back" exhaust is all 1 unit.....and I don't recommend cutting it....unless you are replacing the whole thing.......although the Walker "cat back" is available in individual parts......which makes the installation MUCH easier.

You may have no issue with the nuts on the exhaust manifold studs.
I soaked mine with PBlaster ahead of time.
I had an issue with 1 of the studs.....instead of the nut turning.....the whole stud turned.......
Then....with the old "Y" pipe out of the vehicle....with 1 stud on it......I worked with the stuck nut......ended up breaking the stud off.....but the nut had turned enough that I had enough stud left to "luckily" be able to thread a new nut onto the shorter stud.
However......I got a new stud.....and put it in place.
I put some high temperature antiseize goo onto the threads of the new stud.....as well as onto the studs for the nuts to go onto.
This should help in the unlikely event that I should have to remove those nuts again.

Another thought.....more power = more stress on the whole drivetrain.......and our transmissions are NOT noted for being very strong.....the 1995 being the worst in the windstar line.
I know from experience......a transmission replacement packs a powerful punch to the personal finances.

I don't mean to lecture....but I will feel pretty bad if I see you posting down the road about a tranny failure.....following a power boost......If I did not mention it.

Wiswind - I take nothing you have to say as lecture. Your efforts in this forum have saved numerous people countless thousands of dollars. HERE HERE. I'm very happy to have your thorough input to bounce my thoughts off of.

Its a good point about 95 being the worst year tranny, but my tranny already went the route of a rebuild 20k ago luckily when I was still working. Unluckily though this happened right when Katrina came so I had to leave it in harms way at the tranny shop during that whole catastrophe. The fluid has been changed once since then and I imagine will soon again be done once I get all this other stuff worked out.

I still must point out though that in 1996 Winnies got a HP boost to 200 from 155 and I do not believe there were "major" revisions in 96 - 99 to the tranny although there were clearly revisions to some degree EVERY year to it. Still my rebuild should have "HOPEFULLY" taken into account all the latest revisions to that beast of a tranny so given the 200HP that all future Windstars managed I'm not too worried about adding 10-15 more HP to my 155 base HP by way of the K&N filter and an upgraded exhaust system.

SEARCHERRR IS ABOUT TO BE A GUINEA PIG FOR THIS OLD PLATFORM. I BET YOU SOME MONEY I'M THE 1ST 95 WINDSTAR OWNER TO PUT IN A NEW JASPER ENGINE, A NEW REBUILT TRANNY, IRIDIUM PLUGS, A K&N AIR FILTER, AN UPGRADED BORLA CAT-BACK EXHAUST WITH A MAGNAFLOW YPIPE ! LOL - In case I get crappy results though I will ask for my OEM setup to be saved in reusable condition.

We shall see what numbers I get on MPG and who knows if I can even find a FREE DYNO DAY somewhere or if I buy that scangauge II thingy I can find out what my top HP is one day. Until then I'll just see if she "pulls" (LOL - like talkin about a sports car) harder.

If in the unlikely or rather unwanted event the rebuilt tranny does fail prematurely I've already decided (unless I'm rich by then) I will go with a Stage 1 upgrade beyond OEM stock setup from either Jasper or Marshall Engines which brings in a higher flowing pump, beefier internal tranny parts, and considerably more torque for towing.

At some point too I'll probably hire some super hot scantily-clad models to hang out in the back seat for massages and a maid/cook service in the center bench. :) Perhaps a call girl for the front passenger seat for those LONG drives. :) :evillol: ha haaaaa... After all that it truly will be what I've called it from the beginning to escape stereotyping: THE PARTY BUS! :evillol::popcorn::grinyes::lol: bow chicka wow wow.... bicka chicka woooooweewooowwwww

Searcherr, I don't know how much you read of other posts, but your low mpg issue came to mind when I read in the following thread, post #51 where low voltage at the O2s can cause low mpg.
http://www.automotiveforums.com/vbulletin/showthread.php?t=893982&page=4

Searcherr, I don't know how much you read of other posts, but your low mpg issue came to mind when I read in the following thread, post #51 where low voltage at the O2s can cause low mpg.
http://www.automotiveforums.com/vbulletin/showthread.php?t=893982&page=4
I noticed that thread, but its too long for me to read right now. I just did search of it for "volts" "voltage" and found a couple things about what you said. Are you saying that I could have a bad alternator?

I'm gonna try the test method from this post:
http://www.automotiveforums.com/vbulletin/showthread.php?p=5692338&highlight=volt#post5692338
and post 51 was informative as well:
http://www.automotiveforums.com/vbulletin/showthread.php?p=5691658&highlight=volt#post5691658

The thing is though. I don't have "any" codes and even the PCM is new.

You know though that is one thing thats bothered me ever since I've owned the van - that I've never had to REPLACE the alternator! lol - The alternator to my knowledge is the factory original and always has put out just fine. Aside from this the wiring at the O2's looks OK from what I recall although I have always had trouble grounding the alternator to the body and this is a KEY grounding point because apparently if this cable isn't grounded well the van will not function at all and I mean I won't even get power to the dome lights if that connection isn't solid. The aluminum casing of this alternator does not help at all either.

Also, the MAF I have installed is a used one from another vehicle. I saved like over $200 getting it, but perhaps its dirty. I'm going to clean it up with some MAF cleaner I bought at Autozone. I hope this is a product that will actually help rather than hurt.

tripletdaddy - I am just now realizing if this voltage thing is it that you may end up saving me a lot of work though I do believe I've tested my "running" voltage and battery voltage when vehicle is off recently. I have not however tested it since I got the van back since the new Jasper engine install.

The Magnaflow YPipe arrived today. I now have the new O2's, Ypipe, and Borla Catback exhaust. I have also obtained the correct ypipe to exhaust manifold bolts from Napa. Advance Auto has them too. I should note that possibly the reason Wiswind couldn't find them besides the dealer is because Napa and Advance Auto are the only two places I found that had them for 1 and for 2 on both sites they are not labeled properly listed under "Exhaust Manifold Bolt & Spring". It eventually led me to this:

Napa:
BK 6003230 Exhaust Manifold Stud & Nut Kit $10.29

Advance Auto:
http://www.partsamerica.com/productdetail.aspx?MfrCode=DOR&MfrPartNumber=03132&PartType=725&PTSet=A
Dorman 03132 Exhaust Manifold Bolt & Spring $10.99

I didn't explore the links you listed, but to clarify this voltage business, the link I provided to page 4 of that thread in post #51, that to my understanding, suggested that if the O2 sensors had low voltage outputs, the pcm would interpret that information such that it would result in poor mpg. This would ocurr I assume as a result of an O2 malfunction, which you will eliminate with the O2 sensor replacements you said you will do. That's just my understanding of what was posted.

Now on the alternator lasting so long, I can say mine on my 95, 3.8 is still original with 145k, but I'm not taking it for granted. I also have a 95 taurus with the same engine and alt. It started to complain and eventually needed replacement at around 60k. The van started to show similiar symptoms, I bought a brush and voltage regulator replacement set as the alts are so $$$$$$, expecting it to go soon, but the problem apparently cleared up on its own, as the light stopped coming on and no other problems fo the past 20k. On both vehicles, I assumed I was having brush problems originally when the light would come on or flicker after a hard acceleration and let off of rpm. Sometimes it would stay on for awhile. I think the voltage regulator eventually died on the taurus and I replaced the whole thing. Now, 10k later, the Napa top of the line alt has a front bearing noise. Ugh!!! I think maybe on the van, the alt light came as a result of excessive loading when we had a battery die and I tried to limp it along too long. I also caused the air bag light,SRS, to come on due to "too low voltage". Problem was, the code wouldn't go away even with a new battery and functioning charging system. Disconnecting the battery did not clear the code and light and inpection won't pass it that way. So, I had to clear it following a special procedure I got from a very helpful dealer.

Helpful dealer indeed.... any dealer willing to share repair info over the phone is like a friggin miracle these days. I guess though they want to be talking to someone competant enough to be able to use the information they give out which probably is most of the time not the case.

If anyone wants to know what I've REALLY been going through these past few months the van has just been half the story. I'm working on 2 vehicles at once. If you have a 3SI membership the revival thread is here for the back tracking: http://www.3si.org/forum/showthread.php?t=337631

STATUS: Today I pulled the van up on the new ramps my sister recently bought me (Thanks sis) and used AeroKroil on the ypipe bolts at all 3 ends. Apparently from what I see there are no other bolts to deal with as it seems the flex pipe is welded with the rest of the exhaust all the way back so depending on how cooperative the rubber hangers are this looks to be a fairly easy/straight forward job provided the ypipe bolts do just come off.

Question: There are flanges at all ends of the ypipe, but do I need exhaust gaskets too? (between the flanges and the manifolds and flex pipe connection)

I pulled the new exhaust setup out of the box to compare fitment points today. The only other modification I see in the new Borla exhaust setup is that the resonator chamber (the one furthest back; not the huge square one) is replaced with straight pipe until you get to the rear of the van where they've put a muffler. There are two connection points for rubber hangers for the muffler, but in the back there is only 1 hanger which would leave the muffler slightly wobbly. Looking closer at this area there is an insane amount of rust that looks like it came in from where the bumper meets the rear panel metal cause the paint is all cracking off there and rust is showing. This must allow water down there regularly rusting everything out. I'm going to have to rig some kind of hanger up to the rusty metal, but that'll be the last thing I do. Happily enough though the muffler will fit perfectly between the tow package and the right side frame n stuff and (lol) has a flared out bit metal end on it sealed in plastic. lol - It'll be the nicest looking part of my Windstar's exterior. lol

If I get far enough along with my car I'll be installing the new exhaust on the van tomorrow (hopefully).

I had typed up the following yesterday, but for some reason got sidetracked and never hit submit.... so here is yesterday's post today! lol
-----------------------------------------------------------------------

Today (yesterday) was a complete bust. Somehow I ended up going into town to the parts store 3 times and ran errands for my mom, dad, and sister and before I knew it the end of the day was met. Oh well. Onto tomorrow.

One thing that was a reason for returning to the parts store at least 1 of the times was that I looked closer at the hardware that came with the Borla exhaust package and low and behold ALL of the necessary hardware is in there! I was told by the Ebay seller that they didn't have the hardware with the setup, but 1 of the 2 boxes that was still sealed from the factory apparently had this hardware in there.

There is an additional metal hanger specifically made for the Windstar subframe that is used for the new muffler at the back end and it actually bolts right into 2 subframe holes that are already there OEM and doesn't even get in the way of the tow package. HOOORAAY! That solved my problem instantly and I think all I needed to do was buy 1 additional rubber hanger though I may be wrong about that as the new pipe setup may not call for it cause of repositioning of 1 of the hangers.... or not. I won't know till I get to installing it.

I'm gonna take pictures so you all can see before I install it.

The last trip to the parts store (perhaps Wiswind told me this already in this thread or another and I forgot... I seem to recall a "deep socket" being mentioned") was for a 9/16" deep socket to remove the manifold nuts holding the ypipe on. The back part actually uses 1/2". Can you imagine my wonderful enlightened amazement when I got under there only to realize in all the tools in my arsenal I did not have a single one that would work for this? AAAAAAAAAHHHHHHHHHHHHHHHHH! I thought about buying the entire deep socket set at Autozone, but cost-efficient thought kicked in and said, "Get ONLY what you need Luke. Use the force when buying." and I compared the price and actually if one day I end up buying all the singles to make a full set I will have come pretty close to the price of a full set anyway.... so just the single this time.

Today I ran late getting started, but I did manage to loosen all 4 nuts on the ypipe to manifolds. Either that AeroKroil is magic juice in a can or the shop did not tighten them on very well "if they even removed them". The problem lay at the ypipe meets flex pipe. Apparently the reason my setup is welded past this junction point is because the bolts holding the ypipe to flex pipe barely resemble bolts on the side that has the exposed threads. The head side of the bolts just seem like they would break off if I put any further torque on them. So since I'm not going to use a torch I guess I'll be going to rent a reciprocating saw with a metal cutting blade from home depot tomorrow. No turning back after that. I'm still debating on where to cut. I guess I should cut right through the weld point.

All 4 O2 sensors are now pulled. I wonder if anyone can confirm this or is even paying attention at this point lol..... but do O2 sensors use air outside the sensor/pipe through where the wires go in? I think I read something somewhere that said they did. In any case the sensor that looked the worst was the front side (left or front bank) upstream sensor which is corroded with white gunk. The rest of the sensors just look as though they've heated up with some blackish/grayish/brownish charring at best and very little deposits. I tape/labeled the sensors as I removed them, but I still believe I will replace them all with the new pipe.

Question: The new Ypipe has a good bit of "waxy" substance (tan colored) at the part (inside) that would connect to the flex pipe. What is that stuff? Should I scoop all of that out of there? or leave it? Is it meant to melt and flow down to seal parts of the exhaust or something or is it just left over material used when this thing was welded together?

The oxygen sensor DO use air from the outside environment.....there is a chemical reaction that is generated by the difference in oxygen content in the atmosphere as compared to the oxygen inside the pipe.
This chemical reaction generates a voltage, which is used by the PCM to determine the oxygen content of the exhaust.

As far as replacement oxygen sensors....I would get the Motorcraft brand for the upstream sensors.
It is possible that they are made by Bosch....but they are made to Motorcraft specifications.
You can get the Motorcraft brand through Rockauto....and you will see that they are not much more expensive.
If you want to save a couple bucks.....you could use the bosch for the downstream sensors.
I would get the ones that are specified for "Upstream" and "Downstream" rather than "universal".....as the electrical wires will be the correct length......and not extra long.....and likely to come in contact with the hot exhaust parts.

Use care in the lead dress to avoid having the wires fall down onto the hot exhaust parts.

ALSO.....be super careful to plug the oxygen sensors into the correct plugs......as they are not keyed to prevent you from that....

My "Y" pipe, on my '96 3.8L had studs on the part that connects to the flex pipe.
The new "Y" pipe did not have these studs......thus the need to buy bolts and nuts to make the connection.
So....I would not worry about breaking these bolts on the old one......as it does not sound like you could re-use them if you wanted to.

You WILL need to do some cutting to remove the old "cat back" system......as it is all 1 unit.
At a guess....I would cut on the old pipe parts......thinner than on top of the weld joints......or where you are cutting through 2 pipes......1 slid inside the other.
The Flex pipe on my '96 is slid inside the pipe from the muffler.

So far the verdict is: Listen to Wiswind

As he said that the Walker brand Ypipe is a good 3rd party unit rather than OEM, that would probably be the best way to go to save money and hassle.

The Magnaflow unit (which I don't believe is made anymore) that I installed today/tonight (from 4pm - 12:30AM - YEAP!!!!! ARRGGHH!!! :banghead:) fits in a "flex" type way. In short the rear bank upstream O2 sensor will NOT thread in once the pipe is in place and after fighting with the damn thing for several hours and finally pulling out a hydraulic jack to gently get it to where it needed to be I was EXTREMELY LIVID .... DID I SAY EXTREMELY? IS THERE A BETTER ADJECTIVE TO USE? IF SO INSERT IT THERE. Of course all the other O2's go in nicely, but it seems my idea of putting in the O2's first at least for this one sensor would've been the way to go. I'm not even sure if after I thread it all the way in if it will not be touching what looks like the power steering rack center body. In any case I will be DONE trying to put in a better performing Ypipe in there and I will make the shop I bought it from take it back and have my trusted shop put the old OEM one back on with the new BORLA cat back exhaust system with it.

Also note: On the OEM Ypipe there are 2 center stability bolts on the Ypipe setup. The new Magnaflow one only utilizes the lowest stability bolt which is probably fine, but just a note that its not like the OEM setup 100%. I also had to cut off the corner of the bracket that the lower stability bolt threads into because it would not fit flush on the metal because it would hit the tranny pan edge. I was not happy to have to deal with this. In any case if I do get the damn pipe off and the O2 fits in with having loaded it first and I yield some better performance and MPG later on I will be happier another day. lol

It is installed and I managed to use the old nuts n bolts with the flanges so I'll probably return the ones I had bought from Napa and save about $11.

Question: Do ya'll think the O2 Sensor touching the steering rack (picture shown) will cause a problem? Rubbing from engine movement? Grounding issues? - I lowered the pipe in order to get the O2 sensor in.

To share a few pictures:

Front manifold O2 setup looking good (FYI - all O2's wire length matched on old and new single part # Bosch 15716; gonna call Bosch tomorrow and ask about the upstream vs downstream thing and I'm hoping the single part # is good enough for both sides of the stream):
http://www.thinkrolland.com/images/externallylinked/95WindstarMagnaFlowYpipeO2Sen-0001-smaller.jpg

Length of the pipe pic and you can see that bracket and stability bolt near the tranny pan where I cut the corner of the bracket off:
http://www.thinkrolland.com/images/ThePartyBus/95WindstarMagnaFlowYpipeO2Sen-0002-smaller.jpghttp://www.thinkrolland.com/images/externallylinked/95WindstarMagnaFlowYpipeO2Sen-0002-smaller.jpg

Here's the one (rear upstream) O2 sensor that gave me trouble installing. Think it will be ok touching the metal of the steering rack?:
http://www.thinkrolland.com/images/externallylinked/95WindstarMagnaFlowYpipeO2Sen-0006-smaller.jpg

Different angle of same rear upstream sensor. Though there is a slight shadow it is definitely touching and perhaps I bent it ever so slightly while slowly carefully tightening it up.
http://www.thinkrolland.com/images/externallylinked/95WindstarMagnaFlowYpipeO2Sen-0009-smaller.jpg


One good thing I noticed Wiswind is that this pipe setup does NOT touch the oil pan and I recall you saying that the Walker brand Ypipe you installed did. I put a light behind that area so I could make sure.

Would appreciate opinions: HERE'S A VIDEO of the O2 Sensor moving as I rev engine and shift gears from P to R to N to D 2 1 and then 1 2 D N then R then P again:

Video LINK of O2 Sensor Moving with MagnaFlow Ypipe in my 95 Windstar (http://www.thinkrolland.com/images/externallylinked/Windstar95-3.8LEngMagnaFlowYpipeO2Sensor.wmv)

ALSO KEEP IN MIND THAT VIDEO WAS TAKE WITHOUT THE CAT-BACK EXHAUST HOOKED UP AT ALL. Don't think it'll make much difference, but good to state it.

It kinda looks like it would be ok all times except when I'm first shifted into Reverse which pushes the O2 forward. All Drive gears seem to push the O2 away from the rack housing. What do ya'll think?