400E cold throttle & ASR problem
 

Firstly, I hope you all had filling and fulfilling Thanksgivings. I hope you
all have as much to be thankful for as do I.

We left for my in-laws' place about an hour away yesterday afternoon in the 400E,but had a problem about 2 minutes into the ride, so we turned around and
took the other car.

The car had sat overnight in the garage, so it was cold starting. Upon
startup, the engine revved to about 3000 RPM for a moment then settled into
an up-down search for a proper idle speed. This took about 10 seconds. The
car idled in the driveway for about 5 minutes while we got the family loaded
up. The throttle for the first mile or so was "jumpy." I applied a light
normal pressure for the low-speed ride out of the neighborhood, and the car
seemed to speed up and slow down slightly- under constant light throttle
position- say about 20-25MPH. Then we accelerated onto the highway and the
ASR light came on, and the car seemed really sluggish, and would not shift
into top gear even at 50+ MPH. The throttle remained "jumpy."

Pulled over and turned the car off. Waited a few seconds and started up
again, but no difference. We limped home and swapped cars for the ride to our
overstuffed evening.

Any suggestions as to what the problem could be.

My 92 400E did that several years ago. It needed an engine wiring harness. They get brittle and crack on 92 models. It also needed a throttle actuator I think. It was pricy, but it hasn't coughed since.

The shifting thing is normal when the ASR light is on. You have to put your foot into the throttle so far that it stays in kickdown most of the time...

The seekng for an idle speed you described would also indicate a problem with the throttle actuator. I'm not a MB mechanic, but I'm mechanically inclined. It's time to send it to the shop, but don't expect to get off easy!

Good luck!