BenzWorld Junior Member
Date registered: May 2012
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2003 C320 hesitating at idle
The car runs well most of the time, but every now and then when sitting at a light the engine RPM drops for a moment and it shudders before picking back up to normal. As soon as the pedal is moved off idle the engine runs properly.
The car has 130,000 miles.
In the last year I have replaced all the vacuum hoses, replaced the intake manifold (the vacuum tubing was deteriorated), replaced the brake booster line, taken apart the throttle actuator and cleaned the carbon element and wiper, replaced the accelerator pedal as its wiper cannot be accessed, replaced the spark plugs, replaced the fuel injectors, replaced the fuel filter, replaced the AC dryer (unrelated but time for it). The plug wires were replaced within the last 5000 miles. All this was done for normal maintenance and the occurrences of the rough idle have decreased, but not completely eliminated.
I have not replaced the MAF sensor nor the EGR components nor plug coils. The alternator hold 13.9 volts with almost no variation.