Bad Maf?

green94droptop

Founding Member
Jul 8, 2001
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Orlando, FL
Need some expert advice here guys...

Been having some bad problems lately. Distrubutor went out. So I decided to replace all parts, plugs, wires, cap/rotor, ignition control module (TFI module), coil. So basically all electrical parts are brand new excluding the MAF and o2 sensors (o2's are like 5,000 miles old).

It has a noticable miss down low (stumble maybe) and it's definity down on power. I ran a cylinder balance test and it said that #7 injector was weak. Two weeks ago I ran a comp test and got perfect numbers across the board, so that's out of the question.

So, today I swapped the #7 injector with the #1 injector and the problem mysteriously went away. But it still drove like crap.

After about an hour of speculating with my buddy, we looked into my MAF, which is a 75mm Pro-M Bullet cal'd for my 24lb injectors. So, I took the sensor out and cleaned it (noticably dirty), put it back in and it still drove like crap. So we thought to unplug it and see if it died. Suprisingly, it ran the EXACT same way. No notcable chance in RPM and it obviously didn't die on us. Drove it around and no different than how it drove then when it was plugged in.

So, my question is, if the MAF (and everything else along with it) was good, when I unplugged the sensor, shouldn't it have died or struggled to idle until the computer adjusted it?

If it should have died or stuggled to idle, is my MAF screwed up?

What else should I try guys? I've got no codes; all the electrical parts are brand new. Do o2's usually go bad w/out throwing a CEL?

Thanks guys!
 
If you unplug the MAF, the computer will go to limp mode and just go off of a set table of values. The major sensors being bad will make this happen. So if your computer was already running on limp mode, there would be no noticable difference in driveability if you unplugged the MAF. But I would try and find somebody that has a MAF calibrated for 24lbers and swap test it. I would check your TPS, timing, and see if any wires are arcing.
 
green94droptop said:
It has a noticable miss down low (stumble maybe) and it's definity down on power. I ran a cylinder balance test and it said that #7 injector was weak . Two weeks ago I ran a comp test and got perfect numbers across the board, so that's out of the question.

So, today I swapped the #7 injector with the #1 injector and the problem mysteriously went away. But it still drove like crap.


Thanks guys!

Cylinder Balance Test (Gas EEC IV only): tests cylinder power contribution on SEFI engines by controlling each injector . Codes received from the ECA are interpreted by the tester and cylinder balance test results are displayed.

Injector(s) bad? would explain why one cylinder is not putting out, even though compression checks out ok.
 
TrueBlue95GT said:
If you unplug the MAF, the computer will go to limp mode and just go off of a set table of values. The major sensors being bad will make this happen. So if your computer was already running on limp mode, there would be no noticable difference in driveability if you unplugged the MAF. But I would try and find somebody that has a MAF calibrated for 24lbers and swap test it. I would check your TPS, timing, and see if any wires are arcing.


It feels/sounds like the car has been in limp mode for a couple days now. I guess that's why it didn't die when I unplugged the MAF.

My goal for tomorrow is to try to find a buddy with a MAF that I could swap test it with.

Thanks.
 
kj2833 said:
Cylinder Balance Test (Gas EEC IV only): tests cylinder power contribution on SEFI engines by controlling each injector . Codes received from the ECA are interpreted by the tester and cylinder balance test results are displayed.

Injector(s) bad? would explain why one cylinder is not putting out, even though compression checks out ok.[/Qoute]

I actually ran two test the other day when I did it. On the 2nd test, it passed. So like I said, today I swapped two injectors and it passed on the first test today.

I think the injectors are alright.

My next issue is tackling the MAF issue.

Anyone know why the www.pro-flow.com website is not working? Have they changed the address/name?
 
when I was having maf issues and had a pro-m, they told me acceptable is anywhere from .6-.8 depending @ idle( I was at .4), so yeah, I would agree sounds like you got a bad maf. I've read that there is a different company that is being opened up soon that can recalibrate the pro-m stuff, forgot the name though, should be run by the same employees from what I've read. Or you could get a C&L, but not many people are fans of those meters, but I've had mine w/no problems.
 
dstanggt50 said:
when I was having maf issues and had a pro-m, they told me acceptable is anywhere from .6-.8 depending @ idle( I was at .4), so yeah, I would agree sounds like you got a bad maf. I've read that there is a different company that is being opened up soon that can recalibrate the pro-m stuff, forgot the name though, should be run by the same employees from what I've read. Or you could get a C&L, but not many people are fans of those meters, but I've had mine w/no problems.


Hopefully tomorrow I can find a new MAF at one of these local speed shops. Maybe they still have some Pro-M's in stock. We'll see.

By the way, the car doesn't even want to idle anymore when the car is cold. It misses and stumbles all over the place.