I have a 91 camaro rs 305 tbi and I cant get it to idle. when I start the car it will barely run, it shakes, the tach goes crazy, it will backfire, and it will try to die. I have replaced the plugs, wire, cap, rotor, coil, fuel pump, fuel filter, knock sensor, ignition module, fuel pump relay, map sensor, tps, esc, and nothing has helped. This is my daily driver and I need it running. Could it be the pick up coil? Anything will help me so much right now.

 

with all youve replaced ,id say youre on the right track, id check the iac first tho,make sure its clean,& check adjustment on it. tgo homepage explainshow to adjust, later jimmy

 

I'd first check to make sure your plugs are in correct firing order. Then I'd check your timing and make sure you're not 180 out.

 

The car has been sitting at work for 2 days and I went in this morning and it started and ran good. I didnt do nothing to it. I can drive it but it will still cut out and backfire and the tach will go crazy. I noticed when it is idleing and I cut on the heat it will start to do it. Would this be ground problem? How could i test the grounds?

 

It's not as much as a ground problem as possibly a low voltage problem. The C100 connector which sticks through the firewall on the drivers side contains all the power for the injectors, fuel pump, etc. If theres not enough voltage getting through there (due to the tar) then it will run bad when other accessories are driven. If the tach is bouncing, then one or more of the cylinders is not firing. If it's backfiring, then it's the ignition system. Check the plug order on the distributor like they said. Check the timing too. If you've checked both of those and everything seems to be in order, use a spark tester and make sure there is an arc going to each cylinder. The cheap (~10.00) spark tester will come with instructions on how to use it.

The IAC wouldn't produce these symptoms. I had a bad IAC once. It'll either Idle really high (start at 1500 or so and continue to climb) or it'll be stuck in one idle spot. If when you start the car, it idles high, then slowly makes it's way down as it warms up, then your IAC is fine.

 

How would tar get in my connector? Also when the tach goes crazy, it will jump around but the car doesnt idle any differant.

 

The C100 has tar in it (or a tar like substance) to keep water out of it. Sometimes it will melt and cover the connectors. How much does the tach jump around? couple hundred RPMS or a couple thousand?

 

have you checked to see if you have water in your gas

 

Most the time it just jumps a couple hundred. How can I clean the c100?