Engine misfire cylinder three

2011 MERCEDES BENZ C300

75,000 MILES • 3.0L • V6 • 4WD • AUTOMATIC

JITHIN MATHEW

MEMBER
71 POSTS

Hello, I have a misfire only cylinder three. I replaced the ignition coil and spark plug for that cylinder as told by Mercedes dealership. I even swapped the coils with a different cylinder but no luck. I think it only misfires on startup. I am suspecting a leaky fuel injector. I pulled the freeze frame data from the car.

Nov 2, 2019 at 6:08 PM

KASEKENNY

✓ASE Certified Mechanic
18,907 POSTS

I think you are on the right path. Do you have the o2 sensor data? If it only misses on start up then I would expect the o2 sensor (short term fuel trim) to come back to normal but start out with a rich condition so the short term should show negative then work back to 0.

Let me know if you have this and we can go from there. However, I would suggest swapping that injector with another cylinder and see if the misfire moves with it.

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Nov 3, 2019 at 2:35 PM