Hey guys, I have a 1991 camaro RS 3.1 v6. I've had a ton of problems with this car, but the thing I have never been able to figure out is why it won't idle. I've replaced the O2 sensor, TPS, knock sensor, plugs and wires, coil, distributor cap and rotor, timing chain, messed with the timing and I have checked for vacuum leaks. I can't get it to start unless I give it gas, then it seems to run a little rough, but drives fine. Anytime I come to a stop it dies. It will not idle. When I was checking for vacuum leaks, I disconnected the brake booster hose and it fired right up, no problem and ran by itself just fine, other than it idled a little high. If I plug up the hose when it's running, then it stalls. Could my problem be the brake booster? I've had this problem for about 2 years and I've had 2 mechanics look at it and can't figure it out. I'm not sure what to try next. I bought a brake booster, but I don't want to replace it if that's not my problem. I've read that it could be the IAC or EGR valve. Is there a way to test those? Any help would be great. Thanks!

 

Sounds like IAC to me, not really sure though, my third gen is carbureted and my Mercedes is mechanical fuel injection (it's a diesel). Checked any codes? Does it run at all or just not idle? Perhaps check the voltage of the injectors or something along those lines. Internal combustion engines need spark, fuel and air. It kinda sounds like the timing chain skipped a tooth but the fact that it runs with the brake booster plugged makes me wonder if you have a bad internal bit to the brake booster that could be a nasty vacuum leak. If it was driving I would suggest checking to see if the brakes worked at all that way you can see if the booster is functioning properly. If it isn't a vacuum issue then you're probably looking at something electrical. If something like the timing chain or distributor gear started to eat itself it would be very evident in the oil. I'm sorry I'm not more help to you but if I think of anything else I will try to help you troubleshoot. Best of luck brother, it might be time to throw a 383 in there.