Okay, a lot of data points here, so bear with me. The car in question is a 2000 E320 4matic with 156,000 miles.

In the winter, it starts fine, but will not go anywhere until the engine heats up. If I try to drive off before the engine reaches AT LEAST 40 degrees C, it simply stalls - as if I had let the clutch out on a manual transmission without giving any gas (not jerky - just bogs down then stalls out). If I'm pointed downhill, I can start it rolling, then put it in gear and drive off, regardless of temperature. This is consistent, predictable, and repeatable. If the ambient temperature is much above 50 Fahrenheit, this is not an issue, at all.

In REALLY cold temperature (for the Southern US) - below 10 Fahrenheit - I sometimes get all kinds of warning lights when I first start the car. If I let it warm up and drive it a bit, then turn it off and restart, the warning lights go away. I can't recall the precise messages I get, but imagine nearly every warning coming up at once on the dash display.

When I'm driving (regardless of ambient or engine temp) and step on the accelerator to get full acceleration, requiring the engine to downshift to 3rd (previously running in 5th or 4th), the shift to 3rd is VERY rough - as if I dumped the clutch on a manual transmission. It's far rougher than any other shift point. Manually selecting 3rd is also a rougher shift than any of the other gears, when downshifting.

And now, a new-ish one. I've always had a bit of "feedback" through the shift lever. It seemed I could feel a bit of the road roughness transmitted into bumps of the shift lever if I rested a finger on it. That seemed inconsequential until today. Today, the shift lever started knocking. Quite loud, as if it wanted to be let in. Since I think it's actually comfortable where it is, I suspect this noise is more a sign of trouble than a request for admittance.

I've included all of these, because I'm hoping they are all connected - meaning only one repair.

I have had it in to a local indy shop, which is highly regarded (Euro-Spec in Hendersonville, NC) about the cold weather startup issue. They adjusted the throttle body twice, replaced a temp sensor, and managed to get a small change in the behavior, but not enough to call it a real improvement.

I also talked to another mechanic (when I had the car in at a local shop for tire rotation and balancing). Their transmission guy (who can't work on it, because he doesn't have the computer equipment to analyze MB) gave me an overview of a couple of things, and said it sounds to him (based upon the cold weather startup issue and the rough shift - I didn't think to mention the "feedback") like somehow the TCU (I think that's what he referred to) is getting improper temperature information. I suspect that's why Euro-Spec replaced the sensor, but I don't think I could be so lucky that it's related to the "feedback".

Any thoughts?

 

As always, Plutoe, you have absolutely nothing to add to any thread. Why don't you go talk to your TV or something?

 

Hi gpseymour,
First, I'd check the following:

1.) ATF is filled to proper level (for the correct temperature)
2.) No seepage at trans adapter plug (if seepage present, then replace with new OEM plug and O-rings; ~$14)
3.) No ATF in TCU (if fluid present, then remove and spray both sides with non-residue electronics spray cleaner until clean)
4.) Clear trans error codes
5.) Reset shift points of trans

Now, take it for a drive to reassess.

When's the last time trans service--ATF, filter, pan seal, drain plug seal--was performed?

Hope this helps.

Gehan