Well folks the solution to my idle problems escaped again. I have replaced the Idle Control Unit, the Cold Start Valve and the Idle Control Valve. I sent the Idle Control Unit back to the remanufacture company to be checked and they say it is working properly. With the little radio shack meter, the electricity in the harness has been checked. The feed to the Idle control unit shows hot at pin 2. It shows a good ground at pin 4. Pins 1 and 5 that go to the Idle Control valve have 10.4 ohms resistance. Pin 2 and 4 show 13.7 volts with the engine running. Pin 2 which is fed by the over voltage protection relay shows around 11.4 volts the same as pin 87 and 15 at the relay. Pin 8 shows voltage when cranking the engine. Pin 3 from the fuel pump shows voltage variances when accelerating the engine.
Vacuum leaks are not apparent, though I have not done a smoke test as suggested. Does anyone have an idea to make a smoke device to test for vacuum leaks? Where would one expect to find a leak that would make the Idle climb to 1500 RPM on startup?
The gas linkage is all greased up and nothing is sticking. The idle stop on the linkage is not hanging up. Any thoughts on how to trouble shoot this problem? The engine manual says to hear the Idle Valve click. I do not hear it click with the ignition going on. Yet the new and the old valves both click when checked directly to the battery. The wires to and from the valve to the control unit show continuity.
What do you think I am overlooking? Mike
1955 Porsche Speedster