Can anyone advise on the following , luke from down under , i purchased a 89 gta 5.7 , i have mechanical knowledge , the car runs with the maf disconnected , it is unplugged , it seems to run solely from throttle position switch , is this possible ? , if so , what modifications would of been done , ? , would the ecm be standard ? , would they have reprogrammed the prom ? , would any wiring be altered regarding ecm ? , cheers luke

 

From what I've read the ECM will default into a speed density mode and the motor will run from that, but should have a service engine light if nothing else was done.

 

That's normal. It runs in limp mode if the MAF is unplugged. Most vehicles do this.

GD

 

Why wouldn’t you want the maf hooked up ?

 

Thankyou for replys , the car came with the maf unplugged , it runs fine , when running , service engine light is on , if i try to insert plug on maf , it runs rough , is it possible for vehicle to be tuned bypassing maf ? , would that be possible ? , if so would they re program the prom , ? , is it a common thing to delete the maf , ? , i havnt any history of vehicle , it arrived with this setup .

 

You can convert to SD; lots of threads on how to do this. I converted my '89 from '165 MAF to '730 SD way back in the day.

 

Always toyed with the idea of running an LS1 MAF w/translator and extended range chip. If I get my hands on a decent Iroc project, I might do that. Before Turbo Dave passed away, he always encouraged me to go that route. But I digress. Keep the MAF...

- Rob

 

The service light would not be on if it were programmed to run without the MAF. And, AFAIK, speed density is not supported on any of the 7165's potential masks - except in limp mode as you are currently operating.

Trying to look for a reason for this to be correct is simply silly. The car is broken and needs to be properly repaired. Despite what you think, it is not "running fine" with the SES light on and the MAF unplugged. It may run, but without the MAF it's not going to run correctly or have full power. Talk to the computer - get some live data and find out what the actual problem is (with the MAF correctly connected).

GD

 

The 165 can be converted to map with the 808 Aussie code

https://www.thirdgen.org/forums/diy-...f-165-map.html

 

Pretty sure Callaway started all of that with the early B2K '7165 ECM's during the mid 80's...

Curious to see if the OP gives it a try.

- Rob

 

Overall , would the following be correct , spark and injector pulsing are controlled by the following , maf sensor , tps , coolant temp sensor , ignition module are these the primary feedback , for injector and spark ?

 

Ignition is controlled by the module in the distributor. The ECU can only make adjustments to timing. It can't.... .say...... turn off the ignition. It doesn't have that capability. And only controls timing once engine RPM rise above 400.

ALL the sensors play a part in fuel control. Primarily the MAF and O2 though. If the MAF is bad it can dramatically alter fueling. Unplugging a bad MAF *often* results in the engine running better. But diagnostics must be performed.

GD