Question about Mercedes-Benz 300-Class

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I have a 1991 300E Benz, automatic tranny. when the engine is cold the engine turns but does not start emmadiately it will take a few tries and it seems the engine splutters for few seconds and when it worms up it seems the ideling is low. complete tune up was done, oxy sensor was replaced but the problem still there. thanks for your help.

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Got same car same problem solved with an ovp relay repair (see you tube). Raymen

Posted on Sep 10, 2013

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When it is cold in the morning, the cold start valve will be opened to give extra fuel to help the start. If it is not opened then it would take longer to start. The cold start gets the feedback from a thermal sensor at the top engine block. Check out this sensor. When it is bad it would tell ECM that engine is warm so the cold start valve is not open. The sensor is cheaper than the cold start valve. The idle spec is 750RPM but I think it is high and wasting fuel. Mine is 600 RPM and its idle is smooth so I wouldn't worry about it is low, as long as it is not hesitating.

Posted on Oct 04, 2009


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