420SEL Rough Idle & Poor Power After Driving - PeachParts Mercedes-Benz Forum

JamesDean · #1 02-10-2016, 09:34 AM

Hi All,

My 420SEL appears to be having some issues.

Primarily, after driving for about an hour at 80 MPH and coming to a complete stop the car will run pretty rough.

Here is a video, this was taken after I got off the highway. Waiting at a red light. I was on my way to work and there are two more red lights in the video. You can see that, each time, the car comes to a stop the economy gauge drops and the car runs rough. Often times one has to mash on the pedal to get it back up to running order.

According to the x11 port, duty cycle hits upper 90%s. I believe this means it is running very lean.

https://www.youtube.com/watch?v=jvpoA0bKE0w&feature=youtu.be

The spark plugs have been replaced.
The fuel filter has been replaced.
The cap/rotor do not have a lot of miles on them either.

It is very consistent in its behavior. Its never on a short trip. I've only seen it do it on a long trip, like my daily commute (1h).

It does burn a decent amount of oil, in the neighborhood of 1 quart every 300-500 miles.

I started daily driving it back in December, since then I've put about 7,000-8,000 miles on it and have gone through at minimum 2 gallons of oil. Its not leaking, I don't see any puddles or anything. I am pretty sure its just burning it. You can tell immediately on cold start that it is burning it.

Thoughts gents?