Motor can't idle right when it gets warm

[jody]

I have a 1983 944. Once the car gets warm it will not stableize on a steady idle. It constantly speeds up and slows down. It does not die, but it goes from 1500 RPM to 500 RPM. The engine just osilates between those figures. It runs fine once you give it gas. Any idea of what could be wrong would be helpful. By the way, the car does not make power until it reaches 4000 RPM. Is this normaL? I'm a first time owner. Thank you already.

[Darin]

There is definately something wrong with the car. The car should idle around 950 RPM. A few things to check are the idle set screw, injectors and distributor. Make sure the idle set screw is set tight. The injectors can be checked by unplugging the injector's electrical connection one at a time with the engine running. When you disconnect one of the injectors and the idle does not change then you have a bad injector. Check outside of distributor for any cracks or carbon tracks. Also check inside distributor cap and rotor for the same damage. Check plug wires while you are at it. Hope this helps locate your problem.

[944Driver]

I have an 83 944 also,and had a similar problem. When the car was driven in heavy stop and go city traffic, the idle would do virtually the same thing. New ignition wires were installed when the engine was rebuilt. I haven't had a problem since.

[Martin Taylor]

Common problem usually caused by a loose engine ground, probably a loose rear cam housing cover (three bolts, the main earth strap bolts to this lifting bracket)check they are tight, the gauges probably flicker with electrical load and the problem will get worse as load increases with the fans.