My '92 Camaro LO3 (193k miles) has been running odd lately. I will try and include every bit of info that I possibly can to help give you guys an idea of what the problem could be.

When the engine is cold, it takes a few tries to start up. Most of the time after you start it, it idles rough and you have to give it throttle in order to keep it running, because once you put it into gear it dies unless you instantly give it at least half throttle.

After a minute or so the car's idle smoothes out, and I can drive it without the car dying. It bogs a little when you first put your foot on the gas, and runs like crap (like it's not hitting on all 8 cylinders) until you hit about 3000 RPMs and then it runs good, until it shifts and the RPMs drop again and it repeats itself.

After driving the car for a few minutes, everything seems to run fine. Throttle response is smoother and the car runs pretty good. It doesn't idle rough, and it doesn't bog. It seems like nothing is wrong at all.

BUT, if you park somewhere and turn the car off, and come back a few minutes later, 50% of the time it will have the same problems that it had when starting cold. It will start right up but idle really rough and bog and want to die, and you have to rev the crap out of it and try to get it above 3500 RPMs and hold it there for about 10-20 seconds until the idle smoothes out and the engine stops missing, and then you can drive and after 20-30 seconds it starts running fine. The other 50% of the time, it starts right up and runs fine, with absolutely no problems.

This is what has been replaced:
Throttle position sensor
PCV valve
Idle air control
O2 sensor
Coolant temp. sensor
MAP sensor
ECU and prom
Fuel injectors

None of this helped. Two different shops have looked at it, hooked the car up to a scanner, and it reported no problems. The car doesn't throw any codes. Whatever the problem is, the computer doesn't recognize it. The car had a full tune up a few years ago, and the fuel filter is only a year old. I don't think that the plugs or wires would cause this problem. The problem is intermittent so I don't see how the fuel pump could be the problem either. My final guess is it could possibly be the fuel pressure regulator, and if that doesn't fix it, maybe the fuel pump?

ANYBODY have any ideas? Help would be greatly appreciated, I am tired of my car running like crap!

 

ANYBODY have a clue? Anyone???

 

Could possibly be the fuel pump. What kind of fuel pressure are you getting? Can you test it when its acting up and then again when its running good to see if there is any difference?

 

I'd guess the problem comes from spark timing. Check the fuel pressure just to make sure, and check the timing.

 

Thanks for the help guys! One of the shops said the fuel pressure was ok, but that was probably when the car was running good. I'll be sure to check fuel pressure and spark timing too