1991 Camaro RS 305 TBI
So since I bought the car the rpms have been surging when it's at idle, but it had always ran fine until about a week ago when it randomly decided to start stalling. The problem is also pretty sporadic, it could be running fine while i drive it to the store and when i come back out it would stall at every stop. So we took it to the mechanic and they said the egr valve was sticking open so they replaced that and said it wasn't stalling anymore (keep in mind the problem was pretty sporadic), but when we went to pick it up it started doing it again. So then they replaced the iac valve...still happened. Finally we replaced the spark plug wires and made sure they were farther away from the engine and now it runs much better. It only stalls now when i just start the car up. If the car has been off for a few minutes then when i start it it will rev up and then stall almost immediately. You basically have to start it and put it in the gear and just go and then it will stop stalling at idle for the ride, but it still surges pretty low like it wants to stall. The mechanics are stumped and so are we, any ideas?

 

I'm surprised no one has piped in yet. Have you checked your vacuum hoses and connections? I actually had to put hose clamps on my vacuum connections to stop my surging. Also, check the ohms on your injectors. Should be in the 1.1 -1.3 range. Check the spray pattern of your injectors. Should be be in a conical instead of straight down or dripping. Last is to check your fuel pressure. A little harder to do in the TBI. Good luck. Bump for anybody's input.

 

Thanks for your input, this had me and everyone I know scratching our heads, and even the first shop we took it to couldn't figure it out. Tried everything you said and replaced a bunch of other stuff too. Finally took it to meineke and it turned out to be what they referred to as the electronic spark control, it's in the back on the driver's side of the engine compartment

 

If it was a vac leak I would think occurs all the time. Unless it is related to heat to intake that seals after heat sunk but I doubt that long shot.

No engine CE codes? I would pull codes regardless of no CE light lit.

Fuel pump is my guess. May want to attach a fuel pressure gauge(needs adapter) to TBI and monitor pressure while under load. I would run the gauge to window with duct tape but that is just me,. Need a passanger to do visual under WOT. Free loaner at auto zone.

 

Sounds like a problem I had a few months ago it was my fuel pressure regulator going bad it started off sporadicly until it got worse and worse.

 

Plug off the egr valve vacuum hose & test drive, the egr control solenoid is probably sticking open at times.