Mass Airflow (MAF) Sensor
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Instructor
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From: Tucson AZ
Mass Airflow (MAF) Sensor
The dealer replaced the MAF sensor on my 1994 C4. I would like to know how they knew it was bad. I have the FSM but could not find any section regarding the MAF. Anyone know where it talks about the MAF in the FSM?
Here is a picture of my new MAF. Looks alot different than the old one. It looks like they added new interface to the harness.
Here is a picture of my new MAF. Looks alot different than the old one. It looks like they added new interface to the harness.
Last edited by conrarn; Apr 5, 2009 at 02:23 PM.
Tech Contributor
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From: Custer, WI
The dealer replaced the MAF sensor on my 1994 C4. I would like to know how they knew is was bad. I have the FSM but could not find any section regarding the MAF. Anyone know where it talks about the MAF in the FSM?
Here is a picture of my new MAF. Looks alot different than the old one. It looks like they added new interface to the harness.
Here is a picture of my new MAF. Looks alot different than the old one. It looks like they added new interface to the harness.
Did the car throw codes for the MAF?
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From: Overland Park Kansas
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Did it fix the problem? Did you ask for old parts to be returned to you?
Burning Brakes
Joined: Feb 2009
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From: Richmond Virginia
If you didn't have a code stored, but were running lousy..they may have unplugged it and found the engine smoothed out (when unplugged the ECM works off preset parameters)--they may have scanned it and found that the amount of air the ECM was seeing going thru the MAF was out of specs--ie working but unaccurate MAF sensor...that's if your ECM is capable of "monitoring" in that way (i'm not sure) OR the tech may have seen enough problems with your style of MAF --that by symptoms he was pretty sure it was bad or there may have been a technical bulletin out on your original problem that led him there 
--frankly you should have asked to speak to the tech and asked him why---they're not all crooks/liers like some people think. I've been turning wrenches 35 years and I sleep pretty good at night and when I don't it's not because I "hosed" a customer during the day...it's because I'm just not as young as I once was 
--frankly you should have asked to speak to the tech and asked him why---they're not all crooks/liers like some people think. I've been turning wrenches 35 years and I sleep pretty good at night and when I don't it's not because I "hosed" a customer during the day...it's because I'm just not as young as I once was
Le Mans Master
Joined: Aug 2004
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From: Metairie Louisiana
hmm.. I wonder if you just spent big $$ on a $6 dollar problem? Did you have MAF error codes? I've never seen that MAF before. It looks a little like the truck/SUV sensor. Does it have a screen on it? Pic of insides?
Last edited by rickneworleansla; Apr 5, 2009 at 10:27 AM.
Burning Brakes
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From: Richmond Virginia
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From: Tucson AZ
Yes, it fixed the problem and there were not codes. I just wanted to know how they new it was a problem so I could fix it myself the next time.
Anyone know what section the MAF is covered in the FSM.
Anyone know what section the MAF is covered in the FSM.
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Thread Starter
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From: Tucson AZ
Le Mans Master
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From: San Diego, Ca
Absent a hard code my experience with MAF's is that they either read the correct air flow or they don't which a simple scan and knowledge of expected values will display. Most Dealer's rely on software (Mitchell has some good stuff) that does this for them making the shop flat rate a better money maker. DIY's generally look for rich or lean fueling and then rule out everything else.
Race Director
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From: Overland Park Kansas
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In my FSM for '89, the MAF is covered in section 6E - Driveability and Emissions. TPS, MAT, O2 sensor, etc... are all in that section.
My "thump" test above is one common test. The FSM says if bad, a code 33 or 34 will be set (on mine). Otherwise a manual check can be performed to confirm function.
MAF value should vary with engine speed and should read the same from both locations at which you can tap the value. It's when those two values differ that the code 33 or 34 is set.
Faulty burn-off relays are another cause (I've heard of) that can cause a MAF to mal-function.
Last edited by GREGGPENN; Apr 6, 2009 at 12:02 AM.
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From: Tucson AZ
The car was hesitating, missing out, cutting off at 6k RPM. They replaced the Opti (second one in 2 weeks) and the MAF.
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From: Sonora CA
MAF Sensor
I had mine replaced at the dealer a week or so ago also. I was getting an intermittant "Service Engine Soon" light. They found an error code.
I have a 94/LT1/Automatic/Coupe. I think the engine runs better, a little hard to tell. However, the "Service Engine Soon" light certainly runs better - haven't seen it since the fix
- WPK
I have a 94/LT1/Automatic/Coupe. I think the engine runs better, a little hard to tell. However, the "Service Engine Soon" light certainly runs better - haven't seen it since the fix
- WPK