mascarpone

hi guys my car has been really frustrating me, it started out with a hesitation at idle, replaced the cap and rotor, spark plugs, plug wires, tps, and cleaned my IAC. I also changed some hoses and corrected the timing a little bit and now the hesitation is gone, and the engine seems to run much stronger, but when i decelerate to an idle the engine stalls. this happens pretty much every time i pull up to a stop sign. any ideas? im completely stumped and right now this is my day to day driving car. also the SES light isn't coming on, so i dont know what else to check. any suggestions would be greatly appreciated!! thank you

Black88Z

What was the timing at before? Whats it at now?

Year, engine, car.....?

Does it run good if your even slightly on the gas? Or does it have a miss/stumble throught the rpm range? If it runs ok other than the idle issue we can rule out tps. I would still check it with a multimeter anyways because its so easy.

Check your fuel pressure, and while your doing it watch the pressure as you let off the throttle. Does it drop more than it should? Also, check your FPR, try kinking/pinching the line and seeing what it does.

Your positive the firing order is correct?

mascarpone

yeah the engine runs beautifully, it accellerates without hesitation or miss. the only time i have an issue is when i come to a stop sign, it stalls out when im in drive. if i throw it into neutral then it doesn't stall. im positive the firing order is correct and the timing is good. before i replaced the tps and the cap and rotor and all that it was hesitating when i tried to accelerate from a stopped position but it always ran smoothly once i was moving

Black88Z

I had a very similar problem and it turned out my PROM wasnt seated well. It took me forever to figure out and i chased down so many bugs and couldnt find anything, now it runs great.

Try this: Engine idling in park, warm. Pull down computer and take off PROM cover plate. Push down (not with excessive force of course) and see what it does. Play with it a bit and see if it'll make any difference. For me, i had to push on both ends of it, but it went from idling at a very rough 500 in park to jumping up to 1000 and running terrific, but when i let off the prom it ran poorly again. Took it out and put it back in and after some playing around got it to work and its running great again.

If you can, try using tunerpro. It will show you exactly what your computer is seeing in realtime, making troubleshooting much easier!

After this id check fuel pressure and do the FPR trick if the problem persists.

bubbazwv

Mascarpone what was your problem...what fixes this...I have the same problem...2.8 mpfi camaro runs strong til hot and come up to a stop sign and it will idle down and quit.....37 lbs of fuel pressure at idle but I didnt check it while driving and coming to a stop due to it was a borrowed guage and I already returned it....getting ready to go out and check and clean iac valve and check more vacuum lines and maf sensor

bubbazwv

Black88z I did change my computer out not long ago so I will also check out the prom chip.....should I disconnect the battery if I have to take the prom out and put it back in?