I have a '94 E320 that has developed an idle that "pulses" from an average
600 rpm up to 750 then down to 500 then it levels out for a while and then
starts the cycle again. It doesn't die,it doesn't care if it is hot or
cold. It's just the way it is. Are there any ideas where I should start to
look to fix? If it matters any, hot starts aren't as good as they could be,
I have to press the gas a bit to make it go.
Sounds like the mass air flow sensor is bad. Not that unusual. Or perhaps
you have developed an air leak on the intake somewhere (you can spray some
carb cleaner around the intake gaskets, etc. to check - if the revs go up,
there is a leak).
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