Ok where to start? I guess ill try and explain my knowledge and what i have done so far.Short story car runs fine if you drive in reverse.Drive forward 30 feet blam code 33.This is a 1987 GTA.It is a unmolested find with 65k miles.[IMG]ftp://ftp.diy-efi.org/pub/gmecm/manuals/1227165/89-165v8MAF.jpg[/IMG]I think this is the same diagram for the 1987 only mine has a startup injector system and no vats am i correct?




Changes i made to resolve this issue:

1. New maf sensor.
2.New relays (maf power,burnoff and fuel pump).
3.Completely and properly rewired the maf from ecm to relays
4.New ecm.

Things i have done to test the maf system:

1.Tested,cleaned,revamped all grounds.
2.Tested all the grounds at the ecm connector
3.Followed the following flow chart at:
http://chevythunder.com/maf_code_33.htm

The end result from the flow chart says i have a faulty MAF.
This is incorrect.I have a brand new one only after installing multiple maf sensors.I also have a known *good* backup.The new one is a microtech the old known good one is a bosh.

Other things to note is the car has a new mat,coolant temp,tps,pickup coil,plugs,cap,rotor,wires.This problem was existent before i over hauled the entire engine due to leaking valve seals and a broken ring.Seems as though this car has sat for many years until me and the second owner got it.

As for the uncommon part: I can completely disconnect the maf and put it on the bench and the engine computer still reads the hg/sec when the engine is running.Viewing live data with a auto xray 9000 It even goes up with the engine revs, Yes that's right it runs like that!As a matter of fact it is the only way the car is drivable!It will set a code 34 with the maf off but wont set the code 33 anymore.Its is a early model 1987 not the late.(Not sure if that matters).
From what i have learned the memcal appears to be correct and un molested.

Where would the ecm get the reading for hg/sec maf with the maf disconnected and even unplugged?I cannot for the life of me figure what the hell is wrong with this car.Im under only the last impression that its the chip.Am i wrong?Please help with this.In my 15 years or wrenching I have NEVER seen such odd behavior in a car.

I hope someone can hear my scream crying for help!Please lend a hand in resolving this.

 

bumpy bump

 

Although i'm by no means an authority on the 165 ecm or the 32b code, If i'm not mistaken when you unplug the maf it reverts to a N-alpha mode (uses tps and rpm to guess at the load) basically meant to limp you home if your MAF fails, but some people say it doesnt run half bad that way..

 

That would explain the hg/sec change i see.Thank you.Im still trying to figure out the code 33 tho.Cant seem to figure this baby out.Set minimum idle air properly and everything.Is the running voltages supposed to be the same as the key on voltages?(for the mass air sensor)

 

There has been many post written on this with alot of info. Check all vacuum lines, even under the plenum, also the throttle body butterfly shaft, plenum and runner gaskets, for any leaks. These codes can be a bear to find, maybe try to find a good working ecm and swap for a test.