racing 380
 

I just purchaced a 1982 380 sl and it idles at about 1800rpms. Cold or hot, it doent matter. I dont not know how long its been doing this or any history. What are some things to look at. I looked for vacuume leaks, mechanical adjustment and some other things. Any Ideas??? greg

Volume of air is the determining factor on engine speed. Your car uses a feedback controlled idle that uses the minimum engine speed to accomplish idling in various conditions.

You have too much air getting in the motor. One hint is that a dead electrical control of the idle valve leaves it full open which lets enough air into the motor to run around 1800rpms.

Idle control is a pulse width modulated control of the valve. Constant frequency, varying duty cycle. The best valiant attempt to shut the valve will look like a 70% on duty cycle.