I have a 87 iroc tpi 350 that idles very rough like it has a big cam in it and runs very rich. Once i rev it above about 2000 rpms it smooths up but returns to symptoms when at idle. I have a code 34 for the maf. This a very expensive part but I dont think this is my only problem. I read somewhere that when you unplug the maf it will run better if the maf is faulty. I can unplug the maf and there is no change at all. Maybe a bad ecm? bad prom? Im so aggravated im thinkin of swapping to a carb. I have replaced IAC, dist module, TPS, coil, and checked all grounds and connections. I also tested the injectors and they all read 16.8 ohms. Any help would be greatly appreciated

 

Try this: Spray starting fluid around all of the gaskets for the intake. If the idle increases you have a bad gasket. I tried this in my '88 Iroc Z with the 5.0L TPI and found that I had a vacuum leak where the throttle mates to the intake plenum. I now have a '88 Trans Am with the same motor and same problem. I did some research and it turns out that the intake is under the most pressure below 2000rpm and when you floor it the intake pressure drops dramatically. On my Z, I only found it with starting fluid. On my T/A I could actually hear it sucking air.

 

Are you sure its running rich for sure? I agree that you probably have a vacuum leak.

 

i had same problem. give you any trouble when starting?

for me it was the fuel regulator

 

For sure its flooding, black circles on the ground under the tailpipes, fumes are very strong at the rear of car. And it starts first bump of the key. I pulled the vacuum line of the regulator and theres no gas in it. Also adjusted the tps to .540 . Rarely but sometimes I can start it up and not touch the pedal and it will idle perfect until I rev it one time then the symptoms return.

 

today I replaced the maf and the ecm w the prom, and still starts right up and floods for about 5 seconds then stalls out. If keep reving it it will keep running. I bought a whole other 88 irocz w all the parts to fix mine so at least i wont go broke trying to figure it out, Im thinkin of changin the cold start injector next, does anyone think that could be the problem?

 

do you lose fuel pressure when the engine is off? ...if the 9th or any injector was leaking.
did you test or replace the 2 relays for the MAF sensor?

 

problem solved! some idiot adjusted the throttle up using the idle screw that youre not suppose to mess with. i backed it off and readjusted the tps and wham o its fixed