1989 560sl idles fast. How to correct idle?
Cold idle is fine, 750rpm operating temp idle 800-1299rpm. I suspect the idle control valve but my mechanic wants to replace the electronic module for $700.+. Any suggestions?
Typically when the idle control valve fails it will idle at a much higher RPM. You can try tapping on the valve and see if the RPM changes. Also, it is very common for this engine to have vacuum leaks. Finally, the idle position switch can fail and the idle will usually be in that range when hot.
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