jonaskoehler4

Viano diesel engine jerking and rough idle

My 2006 Mercedes Viano diesel is giving me fits. At 189837 km, I'm getting jerking when accelerating, the check engine light is on, and the error memory shows something related to air intake. Engine power feels reduced. Sometimes it stalls when idling, the engine runs rough, and there's a strong exhaust smell, almost like unburnt fuel. I've checked air filters and MAF sensor connections. I suspect a gasket leak in the air intake manifold, possibly due to scorching, affecting the manifold pressure readings. Has anyone experienced something similar with their car manifold?

4 comment(s)

Sounds frustrating. I had similar symptoms on my Vito jerking, rough idle, and that awful exhaust smell. Definitely check the air intake manifold. A common issue is a leak developing around the manifold sensor. Have you checked the manifold pressure readings with a scan tool? What values are you seeing at idle and under load? That might give you a clearer picture before you start tearing things apart.

Thanks for the quick reply! I did a quick check of the manifold pressure, but I wasn't really sure what the acceptable ranges are. Do you remember what readings you were getting when you had the issue, and what kind of values I should be looking for at idle and under load to confirm a gasket leak? Also, did you notice any visible scorching around the manifold itself when you inspected it?

Honestly, I can't recall the exact manifold pressure readings off the top of my head, but they were significantly off from the expected values way too low at idle, I think. I'd suggest searching online for the expected manifold pressure values for your specific engine code. Regarding scorching, I didn't see anything obvious at first glance, but once I removed the manifold, it was clear there was a gasket leak. You might be better off taking it to a decent workshop, they have better diagnostic tools to pinpoint the issue.

Thanks for the advice! I appreciate you sharing your experience. I took it to a workshop as you suggested. Turns out the intake manifold was indeed defective, with a significant gasket leak. The total repair cost, including parts and labor, came to 1180€. At least it's running smoothly again now!

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