Check engine light on, then turns off.

[xmodster3o3]

My 91 X check engine light turns on after driving about 10 mins, When I get home I turn the engine off. When I turn it back on about 10 sec later, the check engine light is off. I did the search and I can't find anyone else with this problem.
Can anyone give me some ideas on how I can rid of this problem, some things to keep in mind are that I recently had the transmission rebuild, and I just did a tune-up.

 

[audiodude332001]

What did you do for the tune up?

 

[xmodster3o3]

Changed spark plugs, changed oil and oil filter, and took off the cone air filter blowed some air to clean the dust out, checked pcv vavle still rattles. A simple home tune-up. Going to change spark plug wires next week.

 

[xmodster3o3]

I was thinking while at work it could maybe be the mass air flow sensor, maybe it got some dirt or something on it, i'm going to try to clean it when the sun comes up.
Hopefully its the problem.

 

[MrShorty]

What codes come up in the self-tests? The computer should store at least one code in continuous memory whenever the check engine light comes on like that. That would point you in the right direction. An easy to read write-up for the KOEO test is found at www.fordfuelinjection.com A more complete set of instructions for both the KOEO and KOER tests is found at www.dalidesign.com/hbook/eectest.html The usual approach to diagnosing the CEL is to run the self-tests. Then resolve the KOEO codes. Then resolve any remaining KOER codes. Once you have pass codes for both of those tests, then resolve any remaining continuous memory codes.
If you post the codes back here, I feel that I can be more helpful if you post which test each code comes from, and also include a reference to which test(s) yielded pass (11) codes.

 

[xmodster3o3]

I believe I have a problem, it says to turn off the engine, as soon as I turn the engine off the light turns off, and doesn't come back on till after about 10 min with the hood closed.
But I do believe I may have found the problem, after coming home from a check up at the tranny shop I noticed a light white smoke coming from under the hood, I poped the hood and noticed smoke coming from around the fuse box and going right into the air intake. I have no idea what is causing this smoke but it does smell like something electric burning or maybe someting plastic, i'm not to sure. So I'm guess that when I turn on the car where ever the smoke is coming from has not heat up yet so theres no problem yet. But as soon as it heats up, it causes the white smoke, which then enters the intake and into the MAF then causing the EEC to turn on the check engine light.
Does this sound like it could be the problem to anyone, also what should I do to find out where the smoke is coming from? It's hard to check with the hood open cause the smoke comes out very light and I guess the hood builds it up to a cloud of smoke. :fire:
Thanks.

 

[MrShorty]

I would still pull the codes. They might tell you which circuit is cooking.
Then, pull the lid off of the power distribution box and see if you can tell which fuse is smoking. If it doesn't appear to be coming from the fuses, lift the box with the fuses in it up and out, and see if it's coming from one of the relays underneath.

 

[xmodster3o3]

Well it's not the distribution box, i'm sure of it, while looking for the wires too look up the codes I noticed the air intake tube was touching the alternator where the belt spins. I couldn't believe that was the problem, it must have happened while I was cleaning out the air filter, so the rubbing caused the white smoke or burned the up rubber. I was so happey to find out what it was. But I still had to make sure, so I drove to Napa to get some Seafoam and there the damn engine light turns back on. I was mad, as soon as I got to napa I open the hood and all the white smoke was back. I checked the tube it wasn't even close to touching it, what could it be.
I then drove home and poped open the hood as fast as I could I then noticed the smoke was coming from right behind the intake manfoild, then I looked even more down and what to I see the damn tranny I just had rebuilt.
I'm thinking it has to do with the tranny now cause I look under the truck where the smoke seems to be coming from and all I see are little spots of tranny fuild right under it. I just think the tranny fuild has a small leak somewhere and is buring up into smoke and into the intake. The leak is no where near the tranny pan the fuild is dropping onto the engine crossmember.
I know nothing about tranny's and where it could be leaking from, can anyone tell me where it could be leaking from?
Man this is really bothering me.

 

[xmodster3o3]

ok MRshorty I tried to run the codes and this is what I got 11,11 then the memory gave out code 41, i'm not sure if I did this right, so I could be wrong. Looking at the code list the 11's mean System pass, and the 41 means one of the following 1.HEGO sensor circuit indicates system lean (right side) or 2.No HEGO switching detected always lean (right side).
Also it turns out the fuild is really oil not tranny fuild, I thought it was tranny at first cause it was clear and i just has the tranny rebuilt, but then I remembered I just changed my oil, and it to is clear, I know I should have just looked at the color red for tranny fuild.
So looking under my truck to see where the oil is coming from, I can't tell where it's coming from, the oil filter is clean and the bolt is tight. I'm thinking maybe its the vavle cover since I had a problem with it leaking before.
I'm taking my truck to the shop today and maybe they can find the leak and fix it.
So I guess wherever the smoke is coming from, it's building up in my engine bay and then being sucked into the intake passing though the MAF and causing the computer to turn on the check engine light, because the engine is not getting enough o2, it's getting what ever the smoke is.
Does this sound right to you guys.

 

[xmodster3o3]

Bump

 

[MrShorty]

Sounds like an explanation. Next thing I'd do is run the KOER test (run the engine to warm up the O2 sensor before the test) and see if that 41 shows up in the KOER test. Maybe try it with the hood up, hood down and with a feel for how much smoke is under the hood and getting sucked into the intake and see under what conditions you can trigger that 41 in the KOER test.