My friends 87 Z28 with 305 TPI holds an idle when it first starts and then drowns itself and nearly killes itself and then comes back alive and repeates it. The FPR, TPS, and timing chain have been replaced. Any ideas? There are no codes also.

Thanks,
Matt

 

How is the cat? I believe a plugged cat will cause this type of problem and won't set a code until the O2 sensor gets hot enough to go to closed loop. If you remove the O2 sensor and start the car, does the problem go away. If it does, the exhaust is restricted, most likely a plugged up cat.

 

Sounds like an IAC(Idle air Control) its a small valve thats below the plennum if thats not it, IT can be anything from Ignition to a vacuum leak

 

I dont know how the cat is but it does not appear to be the problem, since this happened so suddenly. Also would the IAC affect performance above idle? When you give it gas it falls on its face just like when the computer raises the idle.

There is also a strong rich gas smell from the exhuast when it runs for fifteen or more seconds. FPR sounds like the problem but has been replaced, is there more to a TPI's fuel supply than the pump, regulater, and injectors?

Thanks, again,
Matt

 

Have you removed the O2 sensor and then started it up to see if the problem went away? At idle, the hole left by the removal of the O2 sensor gives the exhaust an alternate way out. If a plugged cat is the problem, the fuel mixture should straighten right out.