1994 Ford Thunderbird v8 - Stumbling accel and failed emissions

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OK so my friend has a 1994 Thunderbird. I am trying to help him fix it. The CEL comes on, and he tells me that when he hits the gas, the engine stumbles for a second, then finally revs. So it stumbles and hesitates to rev. So he just ignores it. I told him "you better fix that or you'll fail emissions" and he's like bah, whatever.

Then his registration expires and of course he fails emissions. The NOX emissions were too high (makes me think egr problem maybe?).

So I tell him to have Autozone scan the codes and he does, but he doesn't write down the codes. Autozone tells him the code means his o2 sensors are bad, so he replaces ALL the o2 sensors. The code does not go away and the problem still happens.

So he tries to replace his EGR valve. In the process he breaks a bunch of plastic vaccuum lines and freaks out because the dealer quotes him some ungodly amount of money for new vaccuum lines. Meanwhile his car now barely runs because of a big vaccuum leak. So I show him that you can just use rubber tubes for the vaccuum lines. Problem fixed... But we still have the original issue.

He says he THINKS he remembers there being 3 trouble codes, and one of them was something to do with the engine running lean. I tell him to get the codes scanned now and write them down but he is too lazy. Day after day I remind him and he never does it. Also I tell him to buy a manual and he doesn't want to.

So, knowing that the code has something to do with running lean, and knowing that the engine stumbles at accelleration, and knowing his NOX emissions are too high... Can anyone give me any possibilities? What could it be? I heard somewhere that it could be a dirty MAF sensor? Anyways, any help is much appreciated. The guy lives pretty far away so next time I visit him I am hoping to have some info. Also since he lives far away I can't force him to get his trouble codes scanned.

If this post makes my friend look like a lazy ass then good... that was part of the intention :D
 
Oh in case I wasn't clear... he TRIED to replace the EGR valve. He did not replace it. After breaking the hell out of a bunch of vaccuum lines, he decided it wasn't possible to reach the EGR valve since it's on the back of the engine.

I told him the manual probably tells you how to remove it but he won't listen. He has some crazy fear of buying a manual or something.
 
FWIW I failed emissions once with my 1994 4.6 and was told by a friend at a shop to change the oil, change air filter if necessary, pour a can of fuel injector cleaner in half tank of gas and be sure the engine is thouroughly warmed up before you get to the test station. Thats all I did and I passed.
 
Quickdraw said:
FWIW I failed emissions once with my 1994 4.6 and was told by a friend at a shop to change the oil, change air filter if necessary, pour a can of fuel injector cleaner in half tank of gas and be sure the engine is thouroughly warmed up before you get to the test station. Thats all I did and I passed.

Was your check engine light on?

My friend did something similar, he put a bunch of fuel alchohol in his gas tank then drove his car about 90 MPH on the freeway, then quickly unplugged his battery to clear the trouble codes, and immediately had it tested. It passed and the check engine light came right back on a few minutes after the test.

That is what I call a half-assed fix... But he got registered!

However, the good news is, I think we fixed it! I found posts online saying that a common cause of this problem is the MAF sensor getting dirty and that cleaning it with electronic contact cleaner can solve it. We tried it, and sure enough, problem dissapeared!
 
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