Mass Air not functioning? Video

1990Coupe

Founding Member
Mar 11, 2002
1,462
132
114
Toms River NJ
Ok so here is my problem - the car will stall on me once in a while. Ive tested different sensors, and even cleaned the IAC.. Im thinking i may get a new IAC. When i come to a red light, and if im downshifting, the car will surge almost and stall. Sometimes when i restart it, it surges and stalls. Most times i just restart it and drive on.. Well messing around under the hood today i unplugged my mass air sensor and i got nothing. no response from the motor. My car is a 4 cyl swap, do you think maybe the computer isnt an a9l.. i havent had a chance to pull the kickpanel and see if it is.. im thinking maybe the computer could be from an 88??? i dunno, but here's a video of it idling
mods are: twisted wedge heads, edelbrock performer intake, 30lb injectors, 77mm pro-m mass air calibrated for 30's, full exhaust with shorties..

http://s80.photobucket.com/albums/j194/javignone/?action=view&current=MVI_0493.flv
 
Well, check the computer to see if it is the right one. did you do the swap of the wire harness your self?

The car sould died as soon as you unplug the maf.

So either it not wired to the proper pins on the computer harness or it not the right computer.
 
The engine will run just fine with the MAF unplugged.

Disconnecting the MAF (or O2's for that matter) forces the computer to use some baseline values for airflow.

Don't expect it to run well though.

Unplugging a sensor is not the right way to trouble shoot the sensor.
The best thing to do is pull the codes.

There are many things that can cause the problems you are having.
Ask the computer what is wrong, instead of just guesing at it.



Let us know what you find,
jason
 
vristang said:
The engine will run just fine with the MAF unplugged.

Disconnecting the MAF (or O2's for that matter) forces the computer to use some baseline values for airflow.

Don't expect it to run well though.

Unplugging a sensor is not the right way to trouble shoot the sensor.
The best thing to do is pull the codes.

There are many things that can cause the problems you are having.
Ask the computer what is wrong, instead of just guesing at it.



Let us know what you find,
jason

Exactly. I hear the ol, well if we still had motors like the 60's things would be simple, and easy to fix. What they don't understand is the computer usually can pinpoint you to what needs to be fixed.
 
90_Red_LX said:
Exactly. I hear the ol, well if we still had motors like the 60's things would be simple, and easy to fix. What they don't understand is the computer usually can pinpoint you to what needs to be fixed.

I definitely agree with that; pre-electronic engines are incredibly easy to work on. There are less than 10 wires involved with making the the engine run.

However, EFI has distinct benefits. The problem is that the troubleshooter needs to have an intimate knowledge of how the EFI system works in order to really get it under control. Believe it or not, the foundation of digital fuel injection is not that complex.

Just an FYI: my '89 GT would idle like crap with the MAF unplugged.
 
65ShelbyClone said:
However, EFI has distinct benefits. The problem is that the troubleshooter needs to have an intimate knowledge of how the EFI system works in order to really get it under control. Believe it or not, the foundation of digital fuel injection is not that complex.

Just an FYI: my '89 GT would idle like crap with the MAF unplugged.

True, the basics of efi aren't that bad.


On your 89...
Had it been modified?
I would think the if the engine had been modified, the EEC default tables for the MAF could be very far from ideal.
But if all components were stock, then the car should have idled just fine.

I'm curious,


jason