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View Full Version : Can I change the 2-3 shift?


obie
06-11-2015, 02:21 AM
Seems to me, sometimes it shortshifts the 2-3 shift, like after rounding an intersection in a neighborhood. Is there anything I can do to manipulate this shift point, or the parameters involved?
Thanks

jmoller99
06-11-2015, 05:37 PM
Have you checked the transmission fluid level? Maybe it needs to be changed or the fluid level is too full or too low.

There is a step (that dealers can do) to tell the TCM to unlearn some operating parameters. Supposedly the DAD can access this and reset it (but on my DAD, it does not fail when I try it, but also does not appear to do anything either).

autostaretx
06-11-2015, 09:36 PM
In addition to what jmoller99 wrote, the TCM (theoretically) "learns" your driving/acceleration habits every time you start the engine.
According to (Buried somewhere) the manual, it looks at the way you accelerate "off the line" for the first ten full-stops after engine start.
Then it tweaks its shift points accordingly for the rest of the trip. (aggressive, hyper-miler, average)

I think i believe it... i have three ways to leave my house: short steep uphill, level, and steeply downhill for a number of blocks and stop signs.
On the days i choose downhill, at least 4 of the first 10 full-stops are on the slope, so the ensuing accelerations require very little engine power.
As a result, the rest of that trip's shift pattern is distinctly weird compared to the uphill and level versions (early up-shifts, if i recall correctly... hence whimpy "take off" when the traffic light turns green).

The DAD-mandated clearing that jmoller99 describes may be removing some "average" of earlier "learning" sessions... the manual is not at all clear about that.

You might try finding an area where you can try different "demands" during the first ten stops of a trip.
Or consciously modify your own habits during the early segments of your normal route.
See if either of those actions has any perceptible effect.

--dick

obie
06-16-2015, 04:40 PM
Thanks guys. I just did an oil change. Level is spot on. I'll try the driving thing.

Paul_E_D
06-16-2015, 04:50 PM
Geeze, I doubt I will ever stop learning about these hidden features.

obie
06-17-2015, 01:06 AM
Well first few drives with early peppy driving moves made. Not sure if there was much difference or it was in my head. Did seem a little peppier though. Run gears out a little longer, or higher revs. The wife drives it more, so she's been instructed. I'll follow later with more data.

Gabe Athouse
06-17-2015, 03:38 AM
Isn't it possible to reset the driving parameters with some fancy key work and rosary beads? All my other Mercedes vehicles this was possible. It can really reinvigorate the vehicle.

obie
06-17-2015, 12:38 PM
THAT would be awesome.

lindenengineering
06-17-2015, 12:44 PM
Obie
As an overview statement you can reset the shift parameters with the right scanner.

It requires some diligent use on the highway inputting the shift points especially with other road users when setting the lower speeds. Have to be carefull about getting a "Kenworth kiss" up yer back side! Now there's a thought!:laughing:

Dennis

Gabe Athouse
06-17-2015, 03:09 PM
So the old merc adaptive ecu trans reset procedure doesn't work on sprinters?

1. Turn the ignition key to the on (not start) position.
2. Press the gas pedal to the floor and hold for five seconds.
3. Turn the key to the "off" position (don't remove the key), then release the gas pedal.
4. Wait at least two minutes for ECU to reset.

obie
06-18-2015, 11:26 AM
5. Then what?

Dennis, Autel scanner work? Maxidas 708.