Been fighting a problem...
Senior User
Joined: Jul 2003
Posts: 318
Likes: 0
From: North of Toronto, Ontario
Been fighting a problem...
My truck was acting up and had no codes like yours. The problem turned out to be a bad MAP sensor. If you have access to another one to try out, take the 5 minutes and change it. Also, these sensors can act weird without going all to crap. Changing this sensor every 2 years or so will pay for itself in keeping up your fuel milage. A plugged cat will not decrease the amount of exhaust flow that you can feel at the pipe with your hand. If the new MAP sensor doesn't fix the problem, the cat is a good place to check next. Try to disconnect and plug the vacume line into the cab for the air controlls. Drive it and see if there is any change. Good luck.
Post Fiend
Joined: Nov 2002
Posts: 9,987
Likes: 7
From: Memphis, TN
Been fighting a problem...
A '94 with 4R70W should be a MAF engine, but wait for qtrmiler to confirm.
The deposits inside the plenum are from excessive crankcase pressure, either from a bad PCV or excessive blowby.
They come from the breather filter, and contaminate the whole intake system.
The deposits inside the plenum are from excessive crankcase pressure, either from a bad PCV or excessive blowby.
They come from the breather filter, and contaminate the whole intake system.
Thread Starter
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Senior User
Joined: Aug 2002
Posts: 301
Likes: 1
Been fighting a problem...
Well, it is a MAF truck. Changed to a cat-less exhaust & saw some improvement, but not a lot like it was. Got it back to about 13 & no check engine light when cold... until I let it sit a week! Gonna try a MAF sensor, sounds right to me. Gonna do a O2 as well since I'm there & it's original too
New User
Joined: Sep 2003
Posts: 19
Likes: 0
From: Saskatoon, SK
Been fighting a problem...
My wife's 86 mustang had what sounds like the exact same problem(which is why we got it for so cheap), and after I pulled the CAT off I still had the problem to a lesser degree. Ended up that I had to remove both the resonators as well 'cuz the carbon and soot from the plugged up CAT had backed up in the resonators too. 'It's feeling much better now'. Of course, if this is the case, then you will likely have to change a fouled up O2 sensor(s) as well. A little tidbit I picked up from the head wrench at the Ford dealer I frequent, also told me that after changing emissions or electrical parts on a Ford, particularly one with an EEC system, that you need to take off the battery cables for about 30 minutes to reset the computer and then take it for about a 10 to 15 mile run on the highway at speed so the ECM can 're-learn' itself.
