85 MAF replacement
Thread Starter
Racer
Joined: Jun 2012
Posts: 343
Likes: 9
From: Long Beach Ca,
85 MAF replacement
Back a few months ago I pulled the MAF and cleaned it with MAF cleaner, screen was dirty. Ever since I have had a high 900 to 1200 rpm idle until it goes into closed loop after warm up, then it seems fine. I bought a remanufactered MAF last night. Got home, and installed it only to find the car will start but not idle, it just dies. I swapped back to the old unit and it's running fine. Does anyone know if you have to do anything to reset the computer when you do a MAF change.
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
No reset needed, about all I can suggest is to check your connector. Be sure all the pins are connecting correctly and that they are clean. I'm sure someone will chime in with a better suggestion, I have never encountered this.
Race Director
Joined: Jun 1999
Posts: 14,924
Likes: 9
From: Merritt Ils Fl
Why would you do that? The MAF feeds the ECM a voltage, Zeroing out the ECM will clear any codes, wonder what ther are, and wipe out short term fuel trim.
LongBeach are you getting a Check Engine light?
LongBeach are you getting a Check Engine light?
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
I'm assuming the fuel trim has been adapting to the old MAF. The same approach is used when replacing injectors.
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
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Race Director
Joined: Jun 1999
Posts: 14,924
Likes: 9
From: Merritt Ils Fl
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
If he can get a scanner on it, I can compare to the stock MAF readings on my 85. Even with the key off it should register a very slight amount of air flow.
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
Try installing the old MAF and start the car. If it idles poorly, try disconnecting the MAF sensor. If the idle improves, the MAF is bad. If there's no change we may need to look elsewhere.
Make sure you didn't accidently disconnect a vacuum hose. There's some small ones near the MAF that go to the A.I.R valve.
Make sure you didn't accidently disconnect a vacuum hose. There's some small ones near the MAF that go to the A.I.R valve.
Safety Car
Joined: Aug 2009
Posts: 3,745
Likes: 275
From: Melbourne, Victoria, Australia
Hopefully your maf will come good after a short drive, remember there is no need to clean a maf ever they have a burn of cycle of when you turn of your ignition. The 85 maf is an analogue one, the only other one i know that works is the 88 digital maf which i have in my 85.
Yes disconnect the battery, that is the first thing to do after any troubles. The ECM will try to compensate and change injector pulse widths and or idle speed, it can get itself in knots.
Check the maf numbers are the same (they are on the side or base of the maf). Then fit your new maf sensor start the engine and turn of the ignition, it will then do a burn off. Disconnect the battery after a minute for at least 30 secs and connect it. The car should start up idle at around 1200 rpm then slowly drop to 600 rpm, drive the car and it will relearn how to manage the engine a little hunting at idle will stabilize after driving with the normal stop light stops and normal driving.
If the idle screw has been adjusted you will need to do the base idle adjustment as per the service manual.
Yes disconnect the battery, that is the first thing to do after any troubles. The ECM will try to compensate and change injector pulse widths and or idle speed, it can get itself in knots.
Check the maf numbers are the same (they are on the side or base of the maf). Then fit your new maf sensor start the engine and turn of the ignition, it will then do a burn off. Disconnect the battery after a minute for at least 30 secs and connect it. The car should start up idle at around 1200 rpm then slowly drop to 600 rpm, drive the car and it will relearn how to manage the engine a little hunting at idle will stabilize after driving with the normal stop light stops and normal driving.
If the idle screw has been adjusted you will need to do the base idle adjustment as per the service manual.
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 412
From: WV
If you do find the maf sensor is your problem, here is what I found.....I went through 3 remanufactured maf sensors when mine went out a few years ago. Every one of them made my car run differently , but none of them made the car run right. One of them wouldn't even allow the car to start..My tuner and I finally came to the conclusion that after rebuilding them, none of the rebuilt maf sensors are anywhere near the original factory specs..Most remanufactured maf sensors are a waste of time, I would suggest trying to find a good used maf sensor that is still within factory specs , then your car will run properly..I finally went a different route going with a aftermarket maf sensor from Blowerworks that uses a sensor blade that's made for the 2005-2010 Ford Mustang and having my tuner adjust my chip to handle it...This was the best choice I have ever made on this car and have had no problems for the last 2 1/2 years...WW
Last edited by WW7; Dec 29, 2012 at 09:45 AM.