Rough Idle and Unusual Crank
08-03-2009, 10:30 PM
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2000 S430
Rough Idle and Unusual Crank
Hello,
I have an idea of what this could be but just want to make sure. Took my car in for a Service B. After I started experiencing rough idling and rough acceleration from a stopped position. Mechanic clean the EGR valve and that seemed to correct the issue for a couple of days. Now its back and for the last couple of days when I start the car.. it turns over 4 or 5 times before cranking. I have researched the forums and see that it is either the MAF, Pedal Sensor, Crank Position Sensor or Spark plugs. Wanted to see if there was any symptoms that would better pinpoint the issue. Thanks.
I have an idea of what this could be but just want to make sure. Took my car in for a Service B. After I started experiencing rough idling and rough acceleration from a stopped position. Mechanic clean the EGR valve and that seemed to correct the issue for a couple of days. Now its back and for the last couple of days when I start the car.. it turns over 4 or 5 times before cranking. I have researched the forums and see that it is either the MAF, Pedal Sensor, Crank Position Sensor or Spark plugs. Wanted to see if there was any symptoms that would better pinpoint the issue. Thanks.
08-06-2009, 08:56 PM
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Update
Well.. I got up enough courage to change the MAF. Took me about 30 minutes... but I felt good about the accomplishment. The car ran a lot smoother but it still rough idled. So I took it to the shop. Since I don't have a CE light there are no codes. The first couple of days they said they couldn't get it to rough idle. I think they just hadn't looked at it yet. Today they said they changed a MAP or MAZ? and the crank position sensor. Not sure what the MAP or MAZ is. Still doing the same thing. Could it be a fuel injector? Spark plug wire? Does anyone know what could cause this that would not cause the CE light to come on? Tomorrow will be 4 days. Hopefully they will have a break through tomorrow. Any help from the forum would be great! Thank you.
08-07-2009, 08:53 AM
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Another Update
They said its not the engine or motor mounts. I was hoping that is what it would be. Tech is saying that it actually skips at times but because the CEL is not on they cant tell whats wrong. They reset the CEL after my service B. It was on when I brought it in.. they probably didnt do a diagnostic then, and i didnt ask them too since its been only been throwing a P400 since I have owned the car. Does anyone know how to force the CEL? Could there be something wrong with that mechanism itself? Come on peeps.. help me out. Feeling alone out here... 
08-08-2009, 07:17 AM
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Mechanic told me the same thing. So, I brought it home. Drove it about 88 miles and still no CEL. It doesn't drive bad though. Made an appointment with MB Bimmer in Huntersville. Describing the problem to them, they said it sounds like a bad spark plug wire. A friend of mine to me that I could verify this by spraying some water or 409 on the wires to see if any fire comes out. Is this true? Is this safe? If I do see fire would it mean the wire was bad? Thanks.
