High Idle @ 1500rpm when car warm/hot, won't kick down below 1000rpm until put in D gear

95

Asked by Jun 13, 2012 at 02:46 AM about the 1991 Mercedes-Benz 300-Class 4 Dr 300E Sedan

Question type: Maintenance & Repair

Been experiencing a high idle issue when my 91 300E is warm/hot. Revs up to 1500rpm and will rev down to 1000rpm when hit the gas pedal but will climb back right back up to 1500 and stay until put in D gear. Any advice?

3 Answers

395

most common is vacuum leak,could be any hose on intake,idle motor might be stuck,but I would check for leaks first,inspect,and listen for hissing noise,to only rev it up 800 rpm its probably small.

ever resolve the issue?

Not yet it don't mis there has to be a idle air valve ... I was thinking that's what airctemp sensor did. ..I tested A.I.T.Sensor shows no ohms

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