Hi. Long time reader, first time caller lol.

I have a 1990 Z32 turbo that I can't keep running without unplugging the MAF and idle control. The idle control portion is pretty easy for me to figure out, probably just need to take a closer look at the idle valve assembly.

When the MAF is unplugged, it runs great as long as I don't give it any throttle. If I give it more than ~1-4% throttle, it'll cut out. I'm assuming that's due to the limp mode. I have heat cycled the car a couple times like that while troubleshooting and not had any other issues come up.

The MAF portion is really causing me some issues, though. I've confirmed fuel pressure (38ish psi at idle no throttle, then ~50 as soon as I touch the throttle.) I have also smoke tested the intake from the MAF to the intake ports and confirmed that there aren't any air leaks that are large enough to not run. Just a small amount making it through the throttle shafts. I have also gathered my pennies and got a consult cable from CZP and checked what the computer is seeing from its perspective. Everything seems to be fine going off of the Z32Wiki quick reference. I had a code for the knock sensor, but I bypassed it with a 1M ohm resistor for now. No codes now. I have also tried swapping for a cheaper RockAuto MAF and it ran the same.

The car has a chip from AshSpec from a couple owners back, and it says it's for 555cc injectors. The connectors have been spliced for the injectors and they're red square ones with the metal clip. I haven't had any luck finding out what the injectors are, but they should be good enough to test on since it runs smooth when MAF is unplugged. I also had the rail out and made sure all injectors fire with a good spray pattern. Did this before firing it up first time in ownership. Should've flow tested them then in hindsight.


MAF plugged in readings while feathering the throttle to keep engine spinning.

This pic is what the readings looked like when I idle it without the MAF plugged in.

Pic of mystery injectors.

ECU Tag for chip.

I've top-bottomed the FSM for a 91 I found online to see if anything rings a bell. Should I break down and try another ECU? I opened up the ECU and did't see anything visibly broken. Looked really clean. I'm out of ideas for this thing. Any ideas are greatly appreciated.

 

Update: turns out the injectors that looked to be 270cc were in fact 270cc. Picked up an adapter kit and arrive aus 550cc injectors and it runs like a dream now.

Time for a 120k service and some maintenance/roadworthiness work😁