Rough Diesel
 

I have a '96 E300D that I bought a couple of months ago. The car's been running great but lately I've been noticing something strange. When I drive along at certain RPM's (typically 2K-3K) the engine seems to 'hunt' up and down about 100 RPM when there is light to moderate load on the engine. It is very noticeable because it feels like the engine is not pulling steadily.

When I speed up the engine smoothens right out. In fact under any heavy load / accelleration conditions, the engine runs very smooth throughout all RPM's. Could this be the Injectors? I've been running a diesel additive with injector cleaner in every other tank.

Also, as it's been getting colder here in Michigan, I've noticed the engine running very rough at all RPM's until it gets up to temp. Even after a 5 min. warm-up in the driveway.

Thanks,
Mike

gersti,

I think what you are describing is a problem when the intake manifold gets gunked up with soot from the EGR and blow-by vapors. This gunk interferes with the movement of some flow control flaps in the intake manifold and as a result the engine does not transition from one operating mode to another as it should (I believe there are two intake runner lengths, and under different throttle positons the intake air flow is altered to favor one or the other path). Do a search on the subject (probably your car and intake manifold flaps) and you will see this is not a unique problem to your car alone. Good luck, Jim

OK, I did a search but couldn't find anything. Anybody have any helpfull hints when it comes to removing and cleaning the intake manifold?

gersti,

Try these:

http://www.peachparts.com/shopforum/diesel-discussion/16247-e300-surging-problems.html?highlight=Intake+and+Flaps

http://www.peachparts.com/shopforum/tech-help/16246-e300-surging-problems.html?highlight=Intake+and+Flaps

or

http://www.peachparts.com/shopforum/tech-help/12313-97-e300-codes.html?highlight=Intake+and+Flaps

or do a search on "intake and flaps" and you will see what I mean. This was apparently a common problem, and, there are apparently also a few fixes. Good luck, Jim