NRL

Anyone notice the 1st gear to 2nd gear torque converter delay that happens when the car sits out in the cold?

So far I've reseached that all Mercedes have a warm up mode that waits for the cats to warm up before the delay goes away; the claim that it does this for emission reasons, mpg.

You can hear the engagement whirring noise when you start up the car, and I did a test by just letting it fully warm up to 80c and you hear when it turns it off.. confirmed the lurch goes away..

No issues when it's fully warmed up, delayed lurch goes away, and the rest of the starts for the rest of the day.

There was a suggestion that the transmission level might be low, so I checked the transmission fluid level after driving around, and it's right between the two lines (80C) mark on the transmission dip stick.

I'm thinking of adding a tad bit more transmission fluid since it was recently sucked out and replaced.

Anyone have any insights? Can I disable the warm up mode that engages something manually in the transmission during the warm up?

Dr Matt

I don't notice this issue on my car even when parked in sub zero weather. Trans seems to work the same on mine.

fastlife23

I have this on my cl65. Read it was something to do with warming up the cats.

grane

Have you checked the transmission mounts? When was the last time you had the read end gear oil replaced? When was the last time you had the transmission fluid/filter "flush" performed? Stating your answers in mileage or years is fine.

I know I have a a different car but: I recently had my 05 CL55 completely serviced/ flushed (12 quarts not the stupid lazy 5 quart MBUSA prescribed job) with .14 fluid. I also had the rear end grease renewed. I always have them check the motor and transmission mounts. ( My car has low mileage about 52k, just use it on long trips, so I use a time interval instead of mileage to have preventative services performed.) I keep a complete logbook of all my services that goes well beyond what the dealer has on record. They used to put these into the MBUSA system but now they refuse because some of the service was not done at a dealership.

The car is much smoother now and there is no clunking. (There wasn't any before but the entire drivetrain is just less noticeable. Seat of the pants opinion.) BTW it was -10 F here last week.

NRL

What's weird is it only happens in the morning/cold start.. and not the rest of the day or night. Car drives awesome. I do have the TCU Tune.

I did another test today where I just let it warm up till the fan came on. No Issue or first gear to second gear lurch.

I added a bit more transmission fluid to see if it's better.. debatable, still happens.

Using the mercedes trans dip stick, (after driving 20 minutes), does the measurement need to be between the two 80c lines or over it? It's right between the two close 80c lines.

It's like I need to use a thinner transmission fluid or something... because the issue obviously is not there when it's warmed up. I'm using Mercedes branded by the way.


Is there any way to reset the TCU with DAS? (other then the TCU Shift learning Reset).

graytalon2000

The whirring noise is the air injection pump. That is normal on a cold start and has nothing to do with the transmission. If the trans fluid and filter have never been changed, I would get that done and go from there.

NRL

hmm, I put in the new speced MB ATF spec 236.14 fluid a few months ago, replacing whatever it was in there before it started to happen.

Maybe I should try the old MB ATF spec 236.10 or 236.12 and see if it's better.

fastlife23

Mine does this and goes away once it is warm my trans is fine.