P0174 Dilema

Well here goes. About a week and a half ago I sarted getting P0301 code (Misfire number 1 cylinder.) See earlier post. I decided to do the plugs and while the cowling was removed I decided to check the EGR ports all were clogged. I cleaned them and replaced the plugs Autolight double platinum. After all was done I seemed to have a rougher idle. It would fluctuate in drive between 600 and 800 rpm. I decided to reset the pcm by diconnecting the battery cable and re-learn the air and fuel mixture. (As a side note I should say for about a year or so I have been getting a P0420 code (catalytic effiency below threshold bank 1.) The van seemed to be running fine but my wife told me yesterday it was running rough and almost died. When I got home I took it for a long ride. No problem.

Now the problem. Today we woke up to 12" of snow and while I was shoveling I started the van to warm it off and defrost everything. When I went to move it it was as if it had no power. I couldnt get the engine to rev under load. It was as if it were starving for air or there was to much back pressure. I thought at first it was on ice and just spinning the tires. That was not the case it would not accelerate under load. It was not burning rich. (No black smoke or gas smell.) It was like it was starving for air or fuel. I took it for a ride and left it in first gear to see how it would drive in higher rpm and it seemed a little better until I got on the expressway. Again no power. No codes no misfire that I could feel. Seemed to idle okay. I brought it home, went to work and when I came home I took it for a ride and it all seems fine. I was a mechanic for 6 years prior to being in consruction for the last 30 so I am usually able to diagnose or at identify what type of problem I might be having. I have to say I am stumped. Im thinking maybe the catalytic converter is going. Thought maybe the iac however thats idle related. The problem is no codes. Accept the catalytic converter. Could that be that intermittent? I am the original owner and have done almost all the work with the exception of the front end work.

Id appreciate any help you all could give. Real smart group. (96 windstar lx 3.8)

Thanks

Sorry about the long post.

bad gas?i seem to be getting one every once in awhile,and dry gas fixes it up.but yours almost seems too bad.this seems like a question for wiswind,he usually knows what's going on.

Well....I can only make a couple of guesses.
The title of this thread is P0174, which is a lean code......almost always a vaccum leak.

Catylist efficiency code is a concern, P0420 is catalyst efficiency bank #1 below threshold.
Bank #1 is the rear bank, and the rear most converter.
I would get under the vehicle (safely) and inspect the oxygen sensor that is mounted into the top rear of the rear most catalytic converter.
Be VERY careful, as mine fell right out of the converter, mounting threads and all.
That would require replacement of the converter assembly to fix.
If the sensor mounting is OK.....I would wonder about the converter(s).....are they possibly clogged?
The both catalytic converters are 1 assembly, also know as the "Y" pipe.
This part lists at about $1600 from FORD.
I have found it online for about $1200.
I replaced mine with a Walker brand "direct fit" for about $320.

Another thing along the converter thought......is the vehicle using any coolant?
If so, you will want to fix that......as maybe that is a possible contributing factor to the converter issue.

Otherwise, as you don't mention that you are getting any codes now, or that you are still getting the P0174 code, I would focus on fuel delivery.
Reason?, air should cause a CEL
Electrical, should cause a CEL
Fuel delivery does not set a CEL.....unless it is something like a clogged injector....which would cause a misfire code....and maybe a lean code......
Fuel filter would be my first thought.....has it been changed lately?
Also, maybe some fuel system cleaner.......a strong one you can get easy....from autozone, etc, would be Berryman's B-12 Chemtool in the metal can.

As far as air delivery....air filter, clean MAF (Mass Air Flow) sensor.....I have pictures of where to get the spray to clean the MAF posted in my pictures.
The actual sensors are located inside the hollow plastic cross member behind that screen. The Idea is to flush the hollow passage out with NON residue ELECTRONIC cleaner....

Thanks for the info Wiswin. The fact that it is intermittent is the hard part to diagnose. The P0174 was 6 months ago and I fixed that with a replacement vacume hose the hose connected to the the plenum near the iac. I used a pre molded one that was used for a bypass on a water pump for a Chrysler I believe. I cut it in two because it had two bends. I now have a spare. I only decided to do the egr port cleaning because I had the cowl off and was chasing down the misfire code. I did a search online and came up also with your advise about the O2 sensor. That will be my next step. I did stop by a muffler shop to ask if they would install a converter that I bought. They told me $150.00 I thought a little high. Im not a fan of doing exhaust work so if it proves to be a converter I will have them do it. I did notice my resivour bottle was dry. I will have to watch that as a possible intake manifold problem. I did the manifold about 80,000 miles ago along with 1 injector. It has been ahwile for the fuel filter and I will replace it. I really think if it was related it would have been getting worse over time and would not be intermittent. I am leaning toward the downstream O2 sensor. I have replaced 2 O2 sensors but 2 remain. Im not sure if either one of those are old.

Thanks for your ideas. Its great to bounce things off others and get fresh ideas.

Unfortunatley lots of snow as you know and hard to work in a 1 car garage. I wish I had a lift.

Thanks

If you replace the downstream oxygen sensor that is mounted into the back of the body of the catalytic converter (the rear most converter was that way on my '96), please take note of my comment on how easy it is to break the sensor mounting stud right out of the body of the converter.
The metal is very thin there....
Mine turned right out of the body.....with only a gentle turning pressure on the sensor......as I was being super careful.....for the very reason I mentioned....and it still broke.

Wear goggles as exhaust work is super dirty.....all kinds of grit dropping down on you.

PBlaster is a good thing to soak threads with......However do NOT get it up onto the sensor body....or down in where the wires go into the sensor.
Reason for that is that the sensor works by a chemical reaction caused by a difference in the oxygen level inside the exhaust at that point, versus the atmosphere......so the sensor material has to have exposure to the atmosphere ....and you don't want to seal it up with oil.....

Also, I would go to the trouble to get a Motorcraft sensor.
Even though, I think, they are made by Bosch, they are made to Motorcraft Specifications.....which is an important distinction.
I bought mine from www.rockauto.com


I bought a "oxygen sensor" socket at the auto parts store.....has a slot on the side to deal with the wires....and helps you to get a good grip on the sensor.

Thanks Wiswin. I havnt got to the sensor yet but I have removed it before. It is one that has been replaced. I will check it out though. The funny thing is the van is running perfect now. No codes. No rough idle and no lack of power. I cant figure it out. That was friday and now its Monday so Ill just wait and see. To cold and to much snow. Ill see what the weekend holds. Thanks

Single digits in the morning (I am just north of you) can bring out strange things in a vehicle, so don't panic if it makes strange sounds, or stumbles.....
Also, this is the first real cold in a while, so any moisture in the fuel system will cause additional strange problems.....especially with the super fast wet, drop in temps that we had.

Actually I had wondered if the intake for the air filter had gotten blocked. I think its under the drivers side front fender. Ill have to check if thats possible. That could explain alot. Ill have to make sure the tank is full and put in some Heat.
Thanks

I got the P0301 on my 96 when the lower intake gasket near the #1 cyclinder failed. My coolant was low and the van would idle rough and stall when backing up or turning a corner. It got bad enough to start blowing white smoke out of the tailpipe.

One unique symptom was that the performance would greatly improve after it warmed up and I drove it awhile. No stallling or rough idle or smoke. But, after sitting all night, it would be at its worst. This was explained to me on another forum to be due to the coolant slowly leaking into the #1 cylinder overnight. Once warmed up, the leak wasn't sufficient to cause the major problems.

My plug on #1 was wet so this may be a quick check for you.

Winny the Pooh Thanks for the info I have been watching the coolant and it is going down a little. The resivoir was empty. I refilled it and the radiator a little but I hadnt checked it in ahwile. (My daughter uses the van.)After the refill I started watching and the resivour is empty but there could have still been some air in the sysytem. There is no white smoke as there was when I replaced the gasket at about 80 or 100,000 miles. I will continue to watch. The plugs however were burning well just a large gap. It all seems to still be working fine except the CEL came on last night again. P0420 looks like its time for a converter. I will check upstream O2 sensor for anti freeze. (As Wiswin suggested. I just have not had time) If that is the problem it could also explain the converter. Except I have been getting that code on and off for years. I just reset and wait for it to come back in a few months. It seems as though its getting worse. It also only comes on after highway driving. Ill post back with findings. Thanks