FraKctured

I've searched posts for transmission issues, and have found some that are similar, but not exactly like what I'm experiencing. So, I'll describe my symptoms--maybe others have similar issues, or others have found a fix.

1. A month ago, I noticed that 1st gear would rev higher than normal (3500) on a non-aggressive acceleration. I thought it might just be the same as in cold weather--heat up for emissions control or something. Didn't think anything was wrong.
2. About 2 weeks ago, downshifting was getting weird. Shifts down from 2nd to 3rd were noticeably harder, as was 2nd to 1st. Knocked occasionally while idling.
3. Problem got worse. Starts off fine, but then 1st and 2nd gear just keep revving without any reason (throttle at 20% tops), then from 1st to 2nd, it kicks up violently, with a noticeable "thud."
4. Shifting gets harder, and happens more quickly after I start driving. Same as above, but exacerbated,

It's a 2006 C280-4M, meticulously maintained, all service done on time, rarely driven very hard, 72,000 miles. I did try the PowerChip at the same time, but only drove it 150 miles with the reflashed ECU, so that can't be the problem (had the ECU returned to fac specs just to be sure).

Any thoughts? From other posts, seems like tranny/rad service (new fluids?) might solve the problem, but, as you can tell, I'm worried about bringing to the dealer because I'm sure the answer will be "Rebuild Transmission."

It just seems hard to believe that the transmission would be gone at these miles.

Glyn M Ruck

Does your car have the 722.9 7 speed? You are right at changeover? There was a delay on 4Matics however.

Early 722.9 transmissions had a few problems with the speed sensor & valve body (electrohydraulic unit). You really need to get this car onto a Star to read the transmission codes & stop a lot of guessing. Seems you have done the 39K miles filter & fluid changes - Yes?

pcy

If I am not mistaken, 2006 C280 4matic has 722.6 transmission.

Frakctured, check the electrical connector on the side of the trans pan, bushing may be leaking trans fluid shorting some of the electrical pins. There's is a metal shield held by one bolt, then you will see the bushing. You can just twist and pull out the connector and see if there is oil.

FraKctured

Thanks guys--the 39K was done, but nothing after that. I brought to the dealer today, so I'll get a readout from STAR soon.
4Matic was 5-speed only at that time for C and E Class (7-speed for S-Class) but I think is now available in 7-speed for E-Class as well.

Glyn M Ruck

OK - If it is 722.6 the check the electrohydraulic bush for oil leaks. Post codes if dealer is confused. You are heading for your next service.

FraKctured

Picked up my car today, appears to be shifting perfectly again. Here's the diagnostic readout--might have been a software update issue. My fuel pump died about a year ago and I had it replaced at an Indy shop. If there was a software update to the fuel system, it probably didn't get done there. (That makes me really concerned about continued Indy patronage--one error like this caused me weeks of anguish, and could have caused thousands of $ to fix if some tranny component was damaged...but that's another thread topic I think.)

Also, the transmission service was not done at 39K as I thought, so I have that scheduled for next week. Could that have exacerbated the problem? Perhaps.

To make it even murkier, this became a problem within 10 miles of a ECU reflash. I had it reflashed to factory specs (PowerChip was totally professional and nice about that and the refund) but that didn't fix the issue. I don't think the ECU reflash had anything to do with this, but it's an odd coincidence that it happened at exactly the same time.

If there were a Butler in the vicinity, I'd be looking at him closely too.

Anyway, I'm posting the diagnostic to get comments from those who know how to read it and to help those who might be having similar issues.

Thanks for all the input and readings on this--always fruitful when the Professors at MBWORLD University provide their input! (I checked the trans pan connector--totally clean)

TYUS

FRACKTURED, WHAT WAS THE DEAL WITH THE INSTALL-AND REMOVAL OF THAT POWERCHIP? WHY DID YOU HAVE IT REMOVED?
THANKS
T=

jlr82

I bought a 2006 c280 with 71k miles on it a few months ago, and the transmission service had never been done. I was experience lots of misbehavior like rough 1-2, 2-3, 3-2, 2-1 shifts, unwillingness to downshift (held on to gears too much), etc.

After having the transmission service done at the recommendation of my dealer I can say it has made a phenomenal improvement. I was pretty convinced something major was wrong with the transmission, but not anymore since it seems much better.

Bottom line, if you've never done the service, do it.