xsboost

Car drives fine threw all gears no jerking no bucking nothing. It just does not
lock up in top gear. As soon as snow clears I will try a fluid flush.
Any other ideas?? the car has 148k

SICAMG

Lock up does not only come on in 5th gear. How do you know it is not?

xsboost

After it shifts top gear, the rpm never drops @65mph 1900-2000rpm.

2000UZJ

Same results in manual mode?

SICAMG

So it shifts and there is no change? Like it does not go into the next gear?
That rpm is about right as well from my own car.

xsboost

So it shifts and there is no change? Like it does not go into the next gear?
That rpm is about right as well from my own car.

it shifts top gear and rpm never drops. In manual mode same
thing.

my G8 and my turbo Buick both run electronic shift trans, I have them set to lock up 52-55mph depending on throttle % with HP tuner software. I wish they made HP tuner for the E55

SICAMG

OK we are on two places with this. " LOCKUP" is when the converter locks. Shifting is when it changes gears. If you feel nothing than there is no shift at all. So something going on with 5th gear. Scan fore codes and see what comes up. You need to make sure the tcu,shifter and conductor plate are all doing there job BEFORE you rule out the transmission's internal fault.

embatch

Hi, did you ever find out what was causing this issue? We’re having the same problem with 2011 E-Class. No error codes showing when it’s plugged in. Torque converter has been replaced but that hasn’t solved the problem. Thanks!

SICAMG

Still the same question for you embatch as well. Does it just not shift to 5th gear or it will not lock up the torque converter?

embatch

It shifts into 5th gear fine, it seems that it’s just not locking up when in 5th.

SICAMG

So when you tip into the throttle the rpm's go up slightly from the converter slip?

insame1

the only way you can tell on these cars is to set up star and do real time data.

bbirdwell

If a clutch pack is slipping the input and output shaft rpm's will exceed parameters and the TCU will put the transmission into limp mode. Not in limp mode, then no problem.

SICAMG

Yea the MIL light would have tripped a long time ago if it had an issue for sure.
The ECU's are very "smart" and have little tolerance for anything especially with miss fires and transmission issues.