Multiple issues...please help

[hpapad01]

Hello everyone,

I hope someone will be able to at least shed some light to my issues. Here is what my 92' 400E is doing most of the time. I say most of the time because sometimes it runs absolutely fine without any issues. I cannot point to any weather or temperature since it is sporadic.

During idle all of a sudden the idle would go up and down, the car will shake, it feels like is going to die on me, but it never does. By pressing the throttle about 1/4 down then I get actual acceleration. Sometimes after pressing the throttle it appears that it goes into the "limp mode". Once I stop the engine and immediately restart everything is working without any issues for a while until the next time.

The ASR light does not come on at all. Never had a problem with the ASR light.

Cruise control is working fine.

From what I have read on this board it looks to me like the Throttle Actuator. Am I thinking correct?

Also, my oil pressure gauge goes to "3" immediately upon starting the car. It stays there until I shut the engine. It does not move at all no matter if idle, running, stopping, etc..

Also, my temperature gauge does not register more than 60 no matter how hot the engine is. I have check, no leaks put new thermostat and flush the radiator. Again is stays between 40 and 60 degrees.

Thank you for taking the time to read my post.

[G-Benz]

Idle problem might be a "surging" from what you describe. This can be caused by a vacuum leak, most likely with one or more of the little vacuum hoses. The air mass sensor may also contribute to this. Check for cracks and/or leaks around the intake hoses just aft of the air cleaner.

The oil pressure needle pegging at "3" usually means a bad sender. Just replaced mine last month for the same issue.

Not sure about the temperature gauge, but I believe that would be the temp sensor. Should be on the coolant pump housing.

Can't comment on the ASR as I don't have that light come on typically...

What I'd like to know is did these symptoms occur simultaneously, or is this just an accumulation of problems?

I ask because it really sounds like a bad main wiring harness. I don't remember what years they were deemed defective, but the insulation would deteriorate and expose the wiring...needless to say, you can imagine what havoc that can create!

You may have some bad ancillary harnesses as well, and they may have contributed to some shorting, that would inevitably fry the sensors attached to them (i.e. temp sensor, oil sender, etc.)

Also, don't be in a hurry to fault the throttle actuator...that is one expensive puppy to replace!

[400E]

I would wholeheartedly agree with everything above, esp. the part about not condemning the throttle actuator. Everything I've read talks about going into limp-home mode while cruising accompanied by ASR light coming on.

There is another thread today discussing 400E wiring harnesses, and one of the posters does comment that limp-home mode can be triggered by a bad harness. I'm due to have mine done; has a number of areas with missing insulation. Check your harness first. An easy place to look at is the wires going to the individual fuel injectors, esp. the brown ground wires as they are not covered by a sheath, only their individual insulation.