Mercedes Repair Questions? Ask a Mechanic for Answers ASAP
Hi, the ECU and the idle control unit will not cause a misfire at idle. If you have a miss at idle and your ignition system is new the problem will typically be a fault with the fuel distributor or with a fuel injector or a vacuum leak at the manifold or low compression. You should first run a compression test to be sure that you have even compression on all cylinders. Next you will need to identify which cylinder is missing and check for vacuum leaks and swap the injector to another cylinder to see if the misfire moves with the injector. I suspect you will find either an injector is bad or there is a vacuum leak at the manifold or you have a bad fuel distributor.
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