Bad MAF? Unplugged it and ran better
Thread Starter
Teching In
Joined: Dec 2017
Posts: 9
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Bad MAF? Unplugged it and ran better Hi all, I created an account to ask this question. been floating around and looking at LS1tech without an account for a while
Anyway I own a 2000 Trans Am and the previous owner had a K&N filter and it was overoiled. He oiled the top of the filter and it was so bad that if I touched it I would have K&N oil all over my finger. I’ve noticed a hesitation since I bought the car at around 2-3k RPMs. I cleaned the MAF with MAF cleaner multiple times and noticed after a few times the hesitation started to not get as bad but was still there. I decided to try an experiment I saw on some forums and unplugged the MAF with the car running. The idle did not change at all idled the same as it always did and no CEL showed up. I drove it around and it felt like the midrange hesitation was gone and it was more eager to rev. Is this for sure a bad MAF? Anymore tests I could do? Another thing that may or may not be related a month ago I had an rear 02 sensor lean condition and replaced all 4 and it went away but still had that hesitation no change. Sorry if this is the wrong subforum for this post.
all reply’s are appreciated Thanks
all reply’s are appreciated Thanks
TECH Senior Member
Joined: Jun 2016
Posts: 22,292
Likes: 3,616
From: Central Cal.
Actually should be in Gen III external, but no big deal. I actually wonder if all the MAF cleanings have affected it. Hopefully you have gotten rid of the K&N filter by now. The MAF does not affect idle, but everything above it.
Thread Starter
Teching In
Joined: Dec 2017
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Oh sorry about that I’ll post in external next time. I think the cleanings might’ve helped. I got rid of the filter as soon as I noticed it was overoiled with a paper filter. I thought the car was supposed to die when the MAF is unplugged maybe I’m wrong. Yeah when I drove it my midrange felt much better than it did with it plugged in. I don’t know if it’s bad for sure though don’t want to just throw a $100+ part at it. Any tests I could do to make sure it’s bad?
The factory tune uses a blend of MAF and map below 4000 rpm. Above 4000 is just the MAF.
When you unplug the MAF the tune switches to just the map ie speed density. It’s a failsafe for a dead MAF.
CEL should have come on.
Anyway, if you still have the K&N just wash the filter real good and don’t oil it.
You may be continuing to goop up the MAF.
When you unplug the MAF the tune switches to just the map ie speed density. It’s a failsafe for a dead MAF.
CEL should have come on.
Anyway, if you still have the K&N just wash the filter real good and don’t oil it.
You may be continuing to goop up the MAF.
Thread Starter
Teching In
Joined: Dec 2017
Posts: 9
Likes: 2
I replaced the filter with a paper filter as soon as I noticed that it was overoiled. So if it was running better with it switched to speed density could that mean my MAF could be bad shouldn’t it run worse with it switched to speed density? CEL didn’t turn on but I only drove it for 5-10min so that could be why
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IIRC, if the hesitation feels like a "cut out," it is a pretty common sign of MAF failure. If it keeps doing it around particular RPM, i think it is another indication that the MAF is suspect.
the other thing i could suggest to you is that you get a wideband and take a good look at your AFR, and some tuning software to log your fuel trims, MAF data, etc. while driving.
The ECM relies heavily on the MAF. Yes, below a certain RPM you have a blend of VE and MAF to calculate cylinder charge, but the bottom line is that that MAF can fubar a lot if it gets screwy, even at idle, low rpm, part throttle...
the other thing i could suggest to you is that you get a wideband and take a good look at your AFR, and some tuning software to log your fuel trims, MAF data, etc. while driving.
The ECM relies heavily on the MAF. Yes, below a certain RPM you have a blend of VE and MAF to calculate cylinder charge, but the bottom line is that that MAF can fubar a lot if it gets screwy, even at idle, low rpm, part throttle...
Joined: Nov 2003
Posts: 6,216
Likes: 236
From: Wichita KS / Rancho San Diego
I had a friend who was experiencing driveability issues - I don't recall whether he got a DTC for the MAF or not. Anyway, I unplugged it and it ran fine, so he drove it around like that for a couple of years.