Attempts stall, Idle Pulses 600-800 rpms, horrible MPG

[searcherrr]

Tripletdaddy - Fun reply to read and all great points.

I wish I had great news, but as usual its only half great.

Status:
1. Returned home yesterday and picked up the van this morning.

2. Test drove it mild, medium, and hard around town and interstate. Seemed fine, but little blip when the radiator fans turn off is still present. I was very very very very very disappointed to feel/see that happen as I know it means there is still something electrical not right. Its not like a "almost stall" now, but more a fast blip where the RPMs dip and come right back up instantaneously.

3. I don't believe it has the power it is supposed to have on the road. It doesn't feel strong like it used to, but I cannot be 100% sure since I've been driving my sports car around in the interim.... though I'm mostly sure it doesn't feel strong. I don't make a habit of getting up to 90mph, but I had to test it fully and between 70-90mph there's a struggle to increase speed. 90 seems to be about all it can do too, which is new. Again, I don't make habit of driving that fast, but I've had it easily at 90 or 95 before without it seeming like it was struggling to get to it.

So..... then.... once home:

NEW TEST RESULTS:

This is ME testing to verify what the shop did. Remember they had it again for 2 weeks.

!!!!!!! DISCONNECTED BATTERY !!!!!!!

GOOD NEWS: Injector 6 and all other injector wires are not shorted to ground.

Test 1 - BAD NEWS: Connected to known good ground & ohming at VPWR in C128 main injector harness connector.
Result: .554 k ohm (not .0554) every time reliably and without use of alligator test clamps. This was probe to probe and my meter probes test 0.00 resistance prior to testing circuits.

Test 2 - VPWR C128 wire to positive battery terminal while positive cable still connected, but negative battery cable still not connected.
Result: .4m ohm ranging up to 4.90 k ohm

Test 3 - VPWR to neg batt cable, batt not connected
Result: .554 k ohm reliably
*I think I should've seen NOTHING happen here, but did.

Test 4 - ECT wires from VPWR C128 main injector connector for comparison
Result: ECT Gray w/Red to VPWR C128: 0.554 k ohm reliably
Result: ECT Light Green w/Red to VPWR C128: 19.33 k ohm steady
*I think I should've seen NOTHING happen with the Gray w/Red stripe wire.

Datalogger information:

TPS 14.9% (Glad to see this reporting now)

Ignition Timing Advance Cyl #1: 26 degrees at full hot

O2 Bank 1 Sensor 1: Rich
O2 Bank 1 Sensor 2: Rich
O2 Bank 2 Sensor 1: Lean/Rich switching
O2 Bank 2 Sensor 2: Rich
*On all 4 though once vehicle was fully warm they seemed to switch Lean/Rich pretty fast though warming up most of the time were Rich.

Load calculated 36% at idle with A/C on

STFT Bank 1 switches Lean/Rich at full hot
STFT Bank 2 switches Lean/Rich at full hot

LTFTB1 15.69% Rich at full hot
LTFTB2 11.72% Rich at full hot

OBD Compliance still not available, but now I think cause its a new PCM this is just how it was in 1995... no compliance maybe was yet available at the time OBDII came out.

Comments welcome on Datalogger findings. Anyone else and Selectron too.... I'd like to hear chatter on the circuit testing I did. I know we've repeated a lot, but from what I see I still have a VPWR short to ground. CORRECT?

The story of horrible bayou voodoo continues....

[searcherrr]

What is the best method to trace where VPWR may be shorted to ground?

What is the most likely place (at this point) to check for a VPWR short to ground?

I have been trying to think of everything thats been touched in that engine bay and of what circuit board type components still haven't been replaced. The ICM comes to mind as one of the few remaining not-replaced circuit board parts, but that may not mean anything if the harness is just shorted somewhere.

I have asked tripletdaddy if he can perform a multimeter Ohm test on the same VPWR wire to Ground (batt disconnected) on his 95 3.8L Windstar to get a reference from another vehicle. Hoping he can do it. Would be nice if any of ya'll could try the same test on your year Windstar. Wiswind's 96 would be a good test too... and anyone elses. I know I'm not supposed to see a value reported for this test, but it'd be nice to see if anyone else does cause then maybe its "normal" for possible residually stored electricity in the system somehow.

I think the fact that when the radiator fans turn off and I see the idle blip down once and then again twice EXTREMELY FAST before normal idle returns, shows that all my wiring work and improving of grounds has weakened the problem whereas before it would almost stall. Now it just seems to be a half second to second dip in idle speed.

[Selectron]

Sorry to hear you still have the blip, Searcherrr, it must have been a big disappointment. The resistance test results look good at first glance - I don't see anything to worry about, but I'll take a closer look at them.

Test 1: 0.554 kilohms (554 ohms) from VPWR to ground - that's fine - see my comments for test 3.

Test 2: Conventional multimeters aren't capable of measuring 0.4 milli-ohms, so I'll assume that 0.4m (lowercase, so milli) should be 0.4M (uppercase, so mega). That would give readings of 4.9 kilohms (4,900 ohms) to 0.4 megohms (400,000 ohms) from VPWR at C128 to battery positive terminal. VPWR doesn't get 12V directly from the battery; instead it takes it from the switched contacts of the PCM Power Relay, which was switched off at the time. Therefore there was no direct path between VPWR and battery positive, so what you have measured is likely an internal resistance within the PCM between the VPWR inputs on pins 71 & 97, and the B+ keep-alive power input (KAPWR) to the PCM on pin 55, which is indeed connected to battery positive at all times, to preserve the PCM's volatile RAM data. Without an internal schematic for the PCM, what that path actually consists of is anybody's guess, but it's safe to say it won't be purely resistive - there is probably considerable circuitry between the two points, and that's what you see on the meter but you can't really draw any conclusions from it. The variation in resistance would have been some of the PCM's capacitors taking a charge via the meter's probes. Having said all of that though, testing resistance between those two points is fairly pointless and not worth repeating.

Test 3: 0.554 kilohms (554 ohms) from VPWR to battery negative cable with battery disconnected. The battery negative cable is at the same potential, electrically speaking, as vehicle ground, so this is the same measurement which you already did in test 1 - hence the same result, so these comments also apply to test 1. Just to explain where that reading of 554 ohms comes from, imagine that you're working on a lighting circuit and you're testing resistance at the 12V feed into a bulb. The battery negative cable is disconnected. Now when you put the meter's positive probe onto the wire which feeds the bulb, and the meter's common probe onto a ground point, you are effectively measuring the resistance through the bulb, eh, so you will see the lamp's filament resistance with, perhaps, other paths in parallel depending on how the circuit is configured. So when you put the meter's postive probe onto VPWR and the common lead to ground, you're measuring the resistance through all the components between the two points, which by the way is many. If you look at the wiring diagram and follow VPWR back to its splice point, you'll see it branches off in many directions. Follow it further and you'll see it branch again, and then I think it branches again, because it feeds a whole host of ignition and emissions systems control devices and sensors. The easy way to visualise that is as a bunch of resistors connected in parallel between VPWR and ground, and you have measured the effective parallel resistance between the two points. Once again, having said all that, the actual resistance figure which has been obtained tells us little except that you don't have a short-circuit to ground, so in that sense it was worthwhile.

Test 4: Resistances from VPWR at C128 to each terminal of the ECT sensor. I shouldn't pay too much attention to those readings. The light green/red wire connects to PCM pin 38, and there's no way of knowing what resistance might be expected between there and VPWR, and then the ECT's grey/red wire branches off all over the place, with series resistances of various sensors along the way, likely with some of them effectively in parallel, thus forming an intricate little series-parallel network, so without knowing the resistance values of all the components, it's not possible to know what resistance might be expected between that point and VPWR, and even if we did know the values, there would still be paths within the PCM for which we could not account, so it really is almost impossible to interpret.

So that all looks good to me, and there's nothing that I would be concerned about.

VPWR is not shorted to ground. If it was and if you applied 12V from the battery then there would be a massive current flow - maybe many hundreds of amps depending on the exact resistance. In fact though you have 554 ohms between VPWR and ground, and if 12V is applied then the current would be 12V divided by 554 ohms, which equals 0.0216 amps - in other words, a mere 21.6 milliamps. That's about the same tiny current which flows through a regular old-fashioned low-intensity LED. It's hardly any current at all. It isn't a short-circuit.

[searcherrr]

I have a digital multimeter from RadioShack and it did show a lowercase "m" on it. I don't know if that means anything except that you know what kind of multimeter I have, but there it is.

Yes, it was a huge disappointment that I still have the blip. Huge.

Thanks for your reply Selectron. I understand your explanations and glad to know them. All I can say is..... "OH." - I'm glad that I don't have a short-circuit to ground, but of course I am still left with the fact that the idle dips twice after the radiator fans cut off. I might assume this is just normal vehicle behavior, but I will never believe that. Only reason I'd assume that is because it used to do this very very very slightly so in the old original engine too. For whatever reason it became very pronounced when the new engine was installed. I wonder if that in itself is a clue.

I haven't tried calling Jasper to report this, but I'm not sure what they'd say. I have tried replacing the rad fans themselves with no luck. Other than that I really wouldn't know where to start cause we've really covered just about everything else there is.

I suppose I can just drive it a while and report back the mileage. I haven't tested fuel pressure yet, which I should. I'll report back with that.

[Selectron]

Yes, it's difficult to know where to go to from here eh, because pretty much everything has been considered by now except the tyre tread depth. Oh yes, I remember now - the fuel pressure testing had to be abandoned when the #6 injector driver went short-circuit. I suppose that would be a good point at which to restart testing then.

[searcherrr]

Fuel pressure is 26 - 28psi. 28psi at idle and it never goes higher. If my system is running right, as it should be now, this would indicate the Ford CD-ROM being wrong everywhere it mentions the pressure should be 30 - 45psi and contradicts all the Ford dealerships I called too. There is one place on the CD-ROM though that states 28 - 30 psi is normal, but that is in a data table that lists all kinds of other information too. Is that data table the only place on the CD-ROM that is correct for the fuel pressure?

26 - 28 psi is when I throttle the pedal.

28 psi is when its idle (again).

Belt is squeaking like mad. I had gotten rid of this until it went to the shop the last time. Only thing I have left to do is replace the belt with a Ford OEM belt. All other tricks have been tried and its extremely aggravating. Its like its shoving its finger in my ear when I'm driving..... after all that care... furiously squeaky belt.

Lastly, I am not sure if this means anything, but the day I got it back I topped off the fuel tank till the pump stopped it 1 time. Usually you can fill it up more and the pump will stop it 1 or 2 more times, but I didn't do that. I stopped when the pump stopped it 1st time. Before filling it I'd noticed the gas meter was at E bottom mark with the light on. I figured at this point I probably only had 2 gallons left, but it only took about 21.5 gallons and its the 25 gallon tank.

Now only after 12 miles the fuel meter is showing the needle just below the blue FULL mark. Did I not fill it as high as I could've? or is excess fuel consumption still an issue? No gas leaks anymore.... none that can be seen. Wonder if I should suck it up and finally put that OEM coil back in there.

EDIT: Forgot to mention, FUEL Pressure rose to 34 psi once I'd turned the engine off. That was new. Never seen it hold pressure that good before. Is it a concern that it rose 6 psi after the engine was off ?

[searcherrr]

I am utterly beaten down by this problem. It makes me want to involve Jasper to find out what is going on. I'm sure their problem solving skills would either find the problem or prove their reman engine has issues.

I am at 1/8 a tank and only have gone 17 miles. Though as I found out today when I went to change the oil, as told, I found the PCV vacuum hose was completely disconnected. I'm more than positive the shop did this. I asked them what they disconnected and the intake pipe was it. I know I didn't leave it that way.

So now for the past 14-15 miles (when I reconnected it) I don't have a good basis for MPG calculation because I had a certain large vacuum leak just before the throttle body.

Now that the vac hose is plugged back in I'll drive it to 1/4 or 1/2 tank and see what my mileage is and do cruise control for as much of that as I can and see where it takes me.

I was going to replace the Performance coils with the OEM coils today, but after I found the pcv hose disconnected I figured I'd drive it around in proper configuration before putting the OEM coil back in.

I will be surprised if the OEM coil changes the situation or improves MPG, but we'll see.

I still have 2 idle blips (falls) after the radiator fans turn off.

After talking to tripletdaddy via PM I'm gonna try a couple more grounding tests related to the CCRM and PCM as soon as I have the patience to push forward again. The grounding black connector near the battery above the radiator I believe is the PCM ground wire. I want to recheck this as I seem to recall testing it produced unreliable results, but I can't remember if it was me or the test that messed up.

[searcherrr]

Well, is good MPG 35 miles to 1/4 a tank?

How on Earth can this be? Almost, everything is new, no codes.... I just do not get it. Shop tells me to drive it 2 or 3 weeks, but I've been this route before.

I don't believe the computer learning period would deduct more than 2x the MPG I should be getting. IF so then you'd have a lot of pissed off people in vehicles of all makes complaining of horrible fuel economy.

Is it possible the O2 sensors could be causing this without throwing a code? I know we've covered those before and Wiswind reported no difference in MPG after replacing his (no codes), but is it possible that the O2 elements are poisoned from fuel or my cleaning procedure using electrical parts cleaner to where they'd throw off erroneous readings?

Grasping at straws now. Don't know what else to grasp at.

[searcherrr]

If every repair makes the gas mileage progressively worse what is that likely to mean? Seriously, every repair has made the MPG worse or just not improved it. The new PCM made the MPG much worse by about 3-4 mpg less.

Is this the tell tale sign that something electrical yet exists still? Tell tale sign of anything?

[searcherrr]

At 5/8 of a tank (about 3/8 tank down from full) and only 50 miles on odo. Used to see 50 miles by 1/8 tank down.

[wiswind]

I would go by how much fuel you add to fill the tank up......as the level indicator likely was changed at some point.....and can vary slightly.
I would guess that the first thing is to have the vehicle running properly......and see how a couple tanks of fuel do......from full to under 1/2 of a tank.
The drivability learning should take place well within 1 tank of fuel.

[tripletdaddy]

Dunno Searcherr. You've replaced so many things especially so close together in time, it would be hard to guess and pinpoint the source. Assuming all else is in good working condition, I would be suspicious of the PCM not operating the engine at top efficiency, thus needing to be reprogrammed. I'm not sure how to go about proving that without researching it, but I'd think the use of a data recording scanner would help. No codes? If so, that doesn't leave much else besides the PCM. The PCM will code if there are problems with the ICM. Perhaps having it hooked up to a dealer like computer analyzer, the really expensive ones, will be the only way to determine what's the problem.

[searcherrr]

I guess I could bring it to the dealer, but I don't even think they have the tools to scan this old vehicle anymore. I really don't even trust the dealers out here. I've had bad experiences every single time going there. Maybe I can call them and see if they can even analyze it. I mean if all they do is check sensor outputs, I already have that. I need a real analysis scan that actually points to something.

[searcherrr]

Refilled the tank today with 7.937 gallons.
Had driven 73 miles (just shy of 1/2 a tank).

73 / 7.937 = 9.20 MPG

Thats city and hwy combined.

Going to put 2 new upstream O2's in tomorrow & put OEM coil back in too and then see if MPG changes.

[tripletdaddy]

"Going to put 2 new upstream O2's in tomorrow & put OEM coil back in too and then see if MPG changes."

You really are grasping at straws!?!

I would expect you having codes resulting from problems with those things you plan on replacing if they are the problem. I don't expect much of a change from changing the coil. Have you pulled any of your plugs to see how clean they are? Or strength tested the spark to the plugs? Both would give you an indication of things not right.

Clearly you have a fuel efficiency problem and no clear cause since most everything checks out or is new, that's why I wondered if the PCM you have isn't exactly right for your van, which is why I wondered if reprogramming it might fix it or at least it be checked to be sure it is right for your van. Your pre-O2s do influence the fuel based on the voltage signal they send to the PCM, with the ideal air to fuel ratio of 14.7 to 1, at least that's what the PCM is supposed to try to get. If you have no codes for them, can your scanner can pull the O2 outputs? The normal operating range is 0.1 volts (very lean) to 0.9 volts (very rich). You can if you want to test them right at the O2 connectors by backprobing them at the SIG wire (positive) and your neg. on a good ground. They warn not to pierce the wires or use an analog meter for these measurements. I assume with cold engine, turn KOEO, you should get between 0.40 to 0.45 volts. If not, then you have a wiring problem. Gees how new!?! It would be a good time to be sure you have good batttery voltage too, 10+volts. Then warm up your engine and you should see the SIG output switch between high and low readings within the previous mentioned range. The post 02s aren't supposed to switch up and down but keep a steady reading also within the same range.

Hmm, is there any chance that you have any parts that have been replaced that are not the right one for your van? Maybe a parts store or shop mistake? Could happen, but thought that might explain things. I don't know, there are SOOOOO many things to check that could be it!?! CKP, ICM, engine compression....stowaways. You hauling a bunch of mexicans around you don't know about? That could kill your mpgs. You get enough of them hiding in there, that's a lot of weight!?! I bet you never looked or thought of that did you.