Does this sound like a bad MAF???

Heg87t

Slightly Compressed User
Joined
Mar 18, 2006
Had the car out yesterday and was not happy with how it ran. 20 miles into my trip the car stumbled and quit while accelerating moderately from a stop sign. Car started back up fine and nothing unusual for the next 30 miles. Stopped for dinner no problem. Headed home and stopped at the store. Came out 45 minutes later and the car started up. Put in gear and press the throttle and it stalled. I took me a good three minutes of turning over and playing with the throttle to get it started after that. I would just about catch then die again.

Drove it to town and back tonight with no problems other than the bad idle and rich fuel smell it has had for a while.

Came home, hooked up Turbolnk and went for a ride. I am going through the data now and trying to figure out what to do.

Observations:

* Idle o2 volts show lean (under 100) most of the time but the car smells rich while idling. Vacuum is 10 - 13 inches.
* Stopped on the road for a couple of seconds then floored it for a run. TPS was over 4.7 but the MAF showed no more than 217 grams when the knock detector went off and I lifted. Log showed 17.2 degrees at 886 mv. :eek:

I drove a little while down the road about 50 mph and the integrator was bouncing nicely above and below 128. MAF was about 35-40 gps. I then matted the throttle and the MAF read 85, 230, 165,176,190, and 202. Only 2.6 degrees when I first hit the throttle and it downshifted to 2nd.

Overall I can't find any integrator or BLM readings under 128 at idle.

Car has a Thrasher chip with 45 PSI fuel pressure running about 13-15 pounds boost.

Can't seem to get 255 GPS. The MAF on the car is the correct code and part number. Don't know if it is a reman. No trouble codes.

Car seems to idle better when I pull and plug the vacuum line to the FPR. Spark plugs were all a uniform white color. No change in idle when tapping the MAF with a screwdriver. I only have vacuum lines hooked up to the FPR, PVC, and MAP trying to isolate any potential vacuum leaks.

The only obvious things lately are that I found 5 of the six screws holding the coil pack down loose and I am getting oil dripping out of the breather in place of the oil fill tube.

Any thoughts??? :confused:
 
It could be the MAF. Does the car run better after the MAF is unplugged? The best way I know of to check a MAF is to use a known good MAF in its place.
I am guessing that you will not max out the MAF at 255 only running 13# - 15# of boost - I would think you need 18# + to hit 255.
 
It could be the MAF. Does the car run better after the MAF is unplugged? The best way I know of to check a MAF is to use a known good MAF in its place.
I am guessing that you will not max out the MAF at 255 only running 13# - 15# of boost - I would think you need 18# + to hit 255.
Thanks for the help. I am going to try unplugging the MAF and the cam sensor one a time to see if there is any improvement. I have a fuel pressure gage in the dash that I need to finish hooking up also to check this out.
I am also going to take apart the coil pack and module to make sure there is no corrosion of other wiring problems.
Also going to take the time to pull the intercooler and check the balancer bolt to make sure it's not loose.

Frustrating!
 
Thanks for the help. I am going to try unplugging the MAF and the cam sensor one a time to see if there is any improvement. I have a fuel pressure gage in the dash that I need to finish hooking up also to check this out.
I am also going to take apart the coil pack and module to make sure there is no corrosion of other wiring problems.
Also going to take the time to pull the intercooler and check the balancer bolt to make sure it's not loose.

Frustrating!

Quick Update:

*I check the battery cables and they were fine.
*Took the coil and module off and there was not anything visually wrong. I had the module tested at the Zone and he said it was great.
*I took the cap off the cam sensor to make sure the ring was fine and all was tight. No problems there though the plug to the cam sensor did not seem to be seated well. I cleaned the plug up, made sure the green gasket was pushed down well and plugged it back in.

I took the car out for a drive after this and it ran really well! No knock on four full throttle pulls. It idled much better and did not have the rich smell from the exhaust. :smile:
I thought the cam sensor plug was the problem till I went and got the car at lunch today. Today it started up very fast. Went up to a pretty smooth fast idle and settled down after a minute. I put it in gear and the rpm dropped and almost stalled. It recovered and I back out of the barn and let it idle for a minute then it went back to it's old loping struggling idle. I got in it and went to leave and it stalled. I spent the next five minutes trying to get it started. :frown: It would just catch then die. Finally got it to start by holding the pedal at about 3/4 throttle to keep the rpm's up. After it was started again it ran pretty good. :rolleyes:

I will try unplugging the MAF if it starts idling bad again to see if it changes anything.

Does it matter exactly where the cam sensor wires are pointing? I have seen some pictures with the wires about 7:00 and mine are 11:00. I set it correctly by rotating the balancer CCW 1.45" and having locking it at the voltage break but could it be ONE tooth off? :confused:
 
Try tapping the maf lightly with a screwdriver with the car idling, if the idle changes or the car stalls the maf is going bad.
 
Try tapping the MAF lightly with a screwdriver with the car idling, if the idle changes or the car stalls the MAF is going bad.

Thanks. I tried tapping it even more than lightly and it did not change the idle. That's when I started looking at the performance of the MAF with Turbolink. :mad: The MAF seems flaky. I thought the cam sensor plug could have been loose putting the car in batch fire mode and causing the rich idle but now it's back to acting bad again with it plugged in well. :frown: I picked up a MAF form a 2000 blazer at the yard last week. I just need to save some money for the translator to change it out.
 
Maybe Making Some Progress...

If you need a MAF translator, this guy has a used one for sale (not in this ad)

http://www.turbobuick.com/forums/pa...t-aluminum-race-style-crank-pulley-razor.html

I just bought a bunch of stuff from him yesterday... and I saw he also had a translator to get rid of. All his stuff is like new and 100%. He's also very reasonably priced and easy to deal with. Alfredo is his name. (he is also HUGE so don't pi$$ him off. lol)

Thanks. I will check that out.

Now I don't think I need one. Drove the car around tonight and it ran pretty good. When I finally put it away I tapped the MAF again with not change. I then unplugged the MAF and the idle got worse and after about 30 seconds it stalled. I don't think it's the MAF now.

I think I need to log some more time with Turbolink on it and see what I can learn. If the cam sensor was really working on and off since the plug was loose I probably need to go through and reset the IAC again now that it's out of batch fire and back to sequential fire mode.

It has the ecm unplugged now so resetting it should help after fixing the loose plug.

That all being said... The car has tricked me before by running good one night and bad the next!! :rolleyes: :wink:
 
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