I have a 89 Iroc 5.7 TPI the last couple of weeks my car starts up idles for a little bit and than stalls out. I'm very confused with no clue. I already did a major tune up. Changing out plugs, wires, cap and rotor, iac, tps, icm and did a cleaning of the iac port. If you have any suggestions let me know please.

 

Need a little bit more info. What are the rpm's at idle? Does it idle smooth or surge? Any mods to the engine other than the tune up? Any additional info would be helpful.

 

On start up when it idles smooth its high and than it smooths out after a few minutes. Also at the light the idle will surge. I have a adjustable fuel pressure regulator, BBK Throttle Body, headers and exhaust that's about it.

 

Ok. Did this problem start after you did the tune up? Check all of your vacuum lines and make sure one didn't get knocked loose when you were working on it. It also wouldn't hurt to test your vacuum. You can get a tester at any auto parts place. Check your fuel pressure too. Same deal on the tester for that. Check it on the passenger side fuel rail. Like I said, start with the easy stuff. You may have an injector problem, but don't go down that road until you check the other stuff first.

Steve

 

Thanks for the information how would I go about testing the vacuum I never did that before i've been looking too see if I knocked anything off but I can't find anything. When im checking the fuel pressure on the passenger side im just unscrewing the piece off the top of the fuel rail and connecting there. What fuel pressure im I looking for?

 

For the vacuum, get a vacuum tester from Advance, Autozone, etc. Connect it to a vacuum line. I usually connect it at the T connector near the vapor canister. Start the car and watch the gauge. It should be above 15" and relatively steady. The needle may dance a little bit. For the fuel pressure, get a tester from same place. Make sure it registers over 50. They sell a fuel pressure/vacuum tester but it only tests fuel up to 15 or 20. Hook up the tester to the valve on the fuel rail with the engine off. Turn the ignition to run, but don't start it. Check the pressure. It should be in the upper 30s. Next, start the car. Pressure should be in the 40-45 range. Needle will dance a bit, just look at the average. Keep an eye on it until it goes into closed loop(warms up). Shut off the engine. If the pressure drops quickly, you've probably got a leaky injector(s). One thing, my car is an 87 IROC with a 350 and I'm basing the above numbers on that. I don't think yours would be significantly different. I'm sure some of the more knowledgeable guys on here will chime in with more suggestions. Let me know how it goes.

Steve

 

Thanks for the Information im out in LA right now when I get back to the Bay im going to test it out.

 

I have a 1991 Z28 TPI 350 it has an extremly high idle in park and neutral but normal idle in all other gears anyone have any ideas.

 

Maybe
https://www.thirdgen.org/forums/tech...high-idle.html

 

Sounds like you IAC may be stuck/not working. Clean or replace. There are some threads on here regarding this. Do a search. It can be a bit of a pain to get that little bastard loose.