Alright I have been having all these idle problems. I have tried replacing several items to fix this. I have replaced my air filter my distributor my plugs my rotor, my throttle position sensor. My TPS sensor tested bad also. Which that made some difference but didn't correct the problem. And things like the air filter that shouldn't have caused the problem like the air filter and the belts just got replaced because I needed them anyway. So what should I do now? I can't really afford to put it in the shop. It's not my daily driver so I don't need the car but I would like to get the mechanical crap taken care of so I can finish restoring the car. Any ideas or suggestions?

 

Set the IAC properly, check plugs/wires/cap and rotor/ignition module. Something as simple as a vacuum leak can disrupt an otherwise smooth idle. Check the rubber hose behind the MAF to make sure the little clamp is on there nice and snug otherwise you'll be allowing "Unmetered" air to enter the system.


Brian P
89 IROC-Z 355

 

Alright man I appreciate it. I am going to give that a try.

 

I have a 86 TA 5.0 30k miles that has a very similar problem. Ity starts, jumps the tach to 2k then jumps around 500 - 1k and quits. Then it won't start at all. But then again sometimes it will run fine for about 10 miles then get jumpy. It's been doing it for about 10 years or so, hence the 30k mileage - I couldn't put 100K on it if I tried! I have had the computer and sensors replaced many times.

Have you been able to fix yours?

sk

 

I had the same problem with a 2000 rpm then cut out idle after putting an engine back together.
What had happened, there were two threaded holes in the plate to which the throttle bodies fit, and which sits on the valley pan.

I had left them unplugged so air went in and caused the 2000 rpm. This made the air bleed valves close, and when that didn't slow the engine, the injectors stopped firing and the engine shut down.

Plugging the holes and rechecking for hoses with air leaks fixed it.

Any air getting into the manifold can cause the high idle speed, so any possible source needs checking.