sammy52401

my 88 iroc, 5.0 tpi, starts and shuts off after a second. i changed my fuel pump, im getting 40 psi to the rails and its holding. i changed the cap and rotor and ignition mod, cant find any vaccum leaks, its got good plugs and wires, and i unplugged the mas airflow sensor, i dont think the alternater is bad cuz, the battery is not being drained. im getting frustrated, any suggestions? thanks

Rolling Thunder

Check out your idle air control valve sounds like it needs some attention. I would recommend at least giving it a good cleaning/inspection or replace if suspect and also cleaning out the ports on the throttle body.

sammy52401

its a tpi car, no throttle body

Awesome-X

Still has a throttle body, even if it is a TPI car. It would be where the throttle blade is.

Rolling Thunder

Yea the throttle body is the part thats bolted to the front of your plenum. You will need to take it off for that but its not too bad with only 4 bolts and a few hoses and wires.

sammy52401

okay, thanks, i will give it a shot.

sammy52401

alright, i changed the idle air control valve, still nothing.

ntomsheck

iTrader: (1)

Try holding the throttle 10-20% in when you start it. Did you test the fuel pressure while it's running for that second or two? does it plummet then? or stay at ~40 even during it's brief run.

sammy52401

tried holding the throttle down and it makes no difference, the fuel pressure never dropped below 40

88gta_hiflyer

iTrader: (1)

I had the exact same problem a month or so back. Turned out to be a bad MAF sensor. I know you said you unplugged it but I would go buy a new one and plug it in just to check. You can always return it if that's not your problem.

Rolling Thunder

When you say your replaced the IAC motor did you actually remove the throttle body and spray throttle body cleaner through the ports to clean them out? This is very important as they often get plugged up so even if the IAC is good it wont work as it should. Next thing i would check is to see if your getting an injector pulse. I know this sounds crazy because it tries to start and its not like you have VATS but hear me out. The ECM fires the injectors based off of a signal received from the distributor but if that signals not received the injectors wont fire. Now how does it try to start if the injectors arnt firing at all? The cold start injector. The cold start injector does not work off the ECM and sprays a brief shot of fuel when its cold to prime the motor. This will allow it to run for a moment.

sammy52401

found the problem, i had the car for two weeks now and the idiot i bought it from couldnt get it running, well he went and replaced the computer and then didnt put the prom in it. no chip, no signal to the injectors, no fire. now it runs great. thanks for all the help, you guys have been very helpful.