Dead MAF?
Thread Starter
Instructor
Joined: Feb 2002
Posts: 227
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From: Greenville TX
Dead MAF?
I have been hunting a rough idle/poor low end power problem for a while now.
This morning I decided to disconnect the MAF sensor and see if that might be the problem. I checked for codes first and had none.
With the engine running, I popped the connector off the MAF sensor. SES light, code 100.
Thought maybe the idle was better. Noticed a knock when reving the engine.
Turned the engine off and reconnected the MAF sensor. Restarted. Code 100 still there, won't erase.
Did I kill my MAF sensor? Was it already dead? Do I drive the car with a dead MAF sensor?
And what about that knock suddenly appearing? It sounds like a lifter.
This morning I decided to disconnect the MAF sensor and see if that might be the problem. I checked for codes first and had none.
With the engine running, I popped the connector off the MAF sensor. SES light, code 100.
Thought maybe the idle was better. Noticed a knock when reving the engine.
Turned the engine off and reconnected the MAF sensor. Restarted. Code 100 still there, won't erase.
Did I kill my MAF sensor? Was it already dead? Do I drive the car with a dead MAF sensor?
And what about that knock suddenly appearing? It sounds like a lifter.
Burning Brakes
Joined: May 1999
Posts: 1,179
Likes: 0
From: waller texas
Cruise-In I Veteran
Re: Dead MAF? (rcdk)
I believe the maf sensor tells the computer to adjust timing and fuel injection.The knock was probably due to the timing being changed by puter since the maf sensor was disconnected.Did you disconnect the battery to erase codes?There is a relay for the maf sensor also and it might be bad.I have a code 36 which relates to burn off of maf sensor which could be maf sensor or the relay.I know when this code shows then it takes more cranking to start engine.From what I have been told by a chevy mechanic the maf sensors were notorious for failure.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Re: Dead MAF? (ZylaRace)
Your mechanic is right. I've now got three "dead" MAFs.
Had a surging, bucking problem a couple of weeks ago and it was the MAF. There was no code either.
I checked all the other stuff first, IAC, TPS, ignition timing, but car still jumped, bucked, surged, etc.
I finally disconnected the MAF WITH THE ENGINE RUNNING and problems went away. I then borrowed a friend's MAF off his 85 and problem was cured.
I was able to track down a replacement and I'm back in business.
If it turns out to be the MAF auto parts stors sell them for $50 with 30 warranty (sometimes less), auto parts stores sell remanufactured ones for $150 exchange or you can check the For Sale board on this site. =Jeff= has one for sale.
With the new MAF, I left the heat sinks in just in case my MAF troubles have been heat related. I did remove the screens though, but I epoxyed a small screen directly in front of the MAF's interior wires to protect them from debris. Best of both works, good airflow and wire protection.
Hope this helps.
Jake
[Modified by JAKE, 6:16 PM 6/11/2002]
Had a surging, bucking problem a couple of weeks ago and it was the MAF. There was no code either.
I checked all the other stuff first, IAC, TPS, ignition timing, but car still jumped, bucked, surged, etc.
I finally disconnected the MAF WITH THE ENGINE RUNNING and problems went away. I then borrowed a friend's MAF off his 85 and problem was cured.
I was able to track down a replacement and I'm back in business.
If it turns out to be the MAF auto parts stors sell them for $50 with 30 warranty (sometimes less), auto parts stores sell remanufactured ones for $150 exchange or you can check the For Sale board on this site. =Jeff= has one for sale.
With the new MAF, I left the heat sinks in just in case my MAF troubles have been heat related. I did remove the screens though, but I epoxyed a small screen directly in front of the MAF's interior wires to protect them from debris. Best of both works, good airflow and wire protection.
Hope this helps.
Jake
[Modified by JAKE, 6:16 PM 6/11/2002]
Burning Brakes
Joined: Aug 2001
Posts: 1,238
Likes: 0
From: walled lake MI
Re: Dead MAF? (rcdk)
...
Did I kill my MAF sensor? Was it already dead? Do I drive the car with a dead MAF sensor? ...
Did I kill my MAF sensor? Was it already dead? Do I drive the car with a dead MAF sensor? ...
the irony is that when you run the car, it will probably won't run too well since usually during a code the MAF reading will default to a fixed or a "guesstimate" value. if my hunch is right, the code will clear during driving, and the engine should run normally afterwards.
hope this works.
Thread Starter
Instructor
Joined: Feb 2002
Posts: 227
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From: Greenville TX
Re: Dead MAF? (tempest)
Ok, the code reset.
The odd thing is that I didn't really notice much difference, but before I drove it I plugged the MAF back in so maybe it was working in spite of the code.
The odd thing is that I didn't really notice much difference, but before I drove it I plugged the MAF back in so maybe it was working in spite of the code.
Drifting
Joined: Mar 1999
Posts: 1,931
Likes: 1
From: Norcross GA
Re: Dead MAF? (rcdk)
The car will still run w/o a MAF, just not as good. The ECM goes into a limp-home mode. (Usese preset fuel/spark values.) i.e. Not the typical closed-loop mode.
If the problem goes away w/ the MAF disconnected, there diag say's the MAF is bad. If it doen't go away, plug it back in, clear teh code, and keep looking.
If the problem goes away w/ the MAF disconnected, there diag say's the MAF is bad. If it doen't go away, plug it back in, clear teh code, and keep looking.
