Thread: Raise 91 300E Idle Speed? Purple wire trick?
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Old 06-13-2014, 08:05 AM
pmckechnie pmckechnie is offline
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Join Date: Jan 2003
Location: Matthews, NC
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I had this exact same problem on my 84 500SEL (big difference I know) and it turned out to be the IAC valve. Cleaning it several times raised the RPM to about 550 rpm at idle.
Cleaning can't hurt so that is a good place to start.

Paul
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84 500 SEL (307,xxx miles)
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