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1996 Mercedes-Benz S320 Question: my rpm goes up and down



, Tarrytown, NY, June 28, 2010, 22:59

it produces smoke from exhaust

2 Answers
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  • Medium-star Best Answer
    patrick mannion from Greg Solow's Engine Room, June 28, 2010, 23:11

    If the RPM is fluctuating it could be from many different things. Something as simple as low coolant level, a vacuum leak at the intake manifold, or air induction. The idle control system could have a problem but the smoke coming out the exhaust, if it is steam due to a blown head gasket the smoke will be white (steam) and maybe smell sweet, if it is excess fuel the exhaust smoke will be black, if the engine is consuming oil the smoke will be gray. It is hard to say what is wrong with out being able to experience the problem first hand.

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  • Answer #2

    September 05, 2010, 20:51

    under the hood on the driver side at the back of engine there is a oil sensor that leaks .change it ,you can get to it under the car .and you can order it at autozone for about $60

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