spyked

Hello all. I have a 2015 GLK 350 4Matic. About 400 miles on it so far. Drives like a dream EXCEPT for a slam/clunk into 4th gear. Here is exactly when it happens:

Driving in 3rd, start to accelerate, then for traffic reasons, have to let off the gas. So many automatics like to upshift when you lift off the gas pedal. Problem is, this car doesn't seem to like that. It slams into 4th gear.

If I keep going faster (don't let off the gas), its smooth as silk.

Hope that makes sense. So, is there a way to reprogram something to get the 3-4 shift with no gas pedal to be smooth like the rest of the shifts?

If not....is the slam into 4th hurting the transmission?

I know some people with other M276 and 7G Plus were having issues with rough shifts, but I don't see that occuring online with the X204.

Any hope in getting this fixed? If it's a new transmission needed, I'd rather just keep what I have IF, and only if, the slam into 4th isn't causing wear and tear.

Thanks!

MBKLUE

It's just amazing this crap continues.... certainly it cannot be doing the transmission any good along with other drive train components. Maybe M-B should source their transmissions from the Japanese. It sure seems like M-B doesn't know what the hell they're doing sometimes...

PeterUbers

3-4 shifting is a nightmare for the 7g tronic ... And 4-3

spyked

Crazy thing is, I just traded in a 2013 C250 with the 7G Tronic Plus. Same unit as in my GLK. In the C250 it was perfect. Makes me think its gotta be software related?

Diabolis

Have the 3-4 TCU adaptation reset by the dealer. The "slam" is because the torquue converter in the 7G Tronic+ has lock-up on all gears.

bop11

If you hard accelerate, as if to pass a truck, and then decide not to, by letting off the gas. Mercedes engineers thought it would be beneficial to down shift on the initial acceleration and then hold that gear should you lift your foot, because that would help the vehicle slow down to get back in behind the truck. I think this is in the manual somewhere. So if you decide to take off from a light with full acceleration and then lift you foot up by more than half, the vehicle will hold what ever gear it is in at that point for an extended period of time. Most cars would just shift up to the gear that it would normally be in if were cruising at that speed. I hate this gear hold but it is what it is. A case of engineers with too much time on their hands.
Similarly I hate the time delay from flooring the throttle until the computers think what gear I want to be in and what mixture and how much gas while that truck is barreling down on me or that lady in the 1980 Honda Civic is beating me off the line. Sure I will catch and pass her but can't I just go? A case of the EPA making car mfg's be more efficient. That 67 Mustang with a 289 and C6 auto never did that!

Diabolis

Actually, that would be a case of engineers that obviosuly care more about your safety and those of others than you do. And yes, you can have instantaneous gobs of power and torque instead of waiting for a turbo to spool up. The Mercedes version is called a C63, but pretty much any car with a naturally aspirated, large displacement engine will do.

spyked

I would be fine if the car held the gear...that's what I prefer in this case actually. My issue is that if I'm in 3rd, and the car senses it's about time to shift to 4th, and I lift off the gas around the same time (you know, to not hit the car sitting in traffic in front of me), it shifts to 4th anyway.


No biggie - many automatics upshift upon lifting the gas pedal, but the 7G Tronic + in this car doesn't do it as smoothly as the 7G Tronic + in my C250. Maybe has to do with increased torque and HP in the GLK350? If I put the car in Sport, it does hold the lower gear (3rd) until later in the RPM range, which is nice. But who wants to drive a 2 TON SUV in Sport all the time to get a smooth 3-4 shift in stop and go traffic?


Not the end of the world, at all, but I find now that I sometimes keep my foot ON the gas UNTIL it upshifts, just so I feel a smooth shift. Then hit the brake if needed. Dealer confirmed all is fine, and the jerk/rough shift isn't actually hurting anything inside. How they know that, I'm not sure, but I'll just keep an eye on it for now.

NYCGLK

I love this feature. If I want to be aggressive, the tranny will stay aggressive until it sees I'm not. noIt's t about slowing down behind a truck it's about car "thinking" that you are in an uncertain situation and may need power to accelerate. At least that's how I always thought of it. It's an active safety feature. Actually if you simply double tap the gas it will downshift.

But this is not the issue of OP. This feature doesn't produce any clunks or hard shifting.

NYCGLK

Sport is just a word used to describe "normal" in MB world. I have 2010 which keeps in S mode at all times. I can't stand the "C" or what is call "Eco" mode in new models and had "sport" on since I bought the car. In sport it also starts in 1st gear instead of 2nd.

maison1306

I just bought a 2015 GLK that does the exact same thing. If you back off the accelerator as it shifts into 4th gear it makes a loud clunk. Not sure if there's a fix but it is annoying. Otherwise the car is great!

boylston

I just traded a 2013 GLK350 4Matic for a 2015 GLK350. The transmission is really rough. The salesman told me "it is still learning my driving habits". I've got about 100 miles on it so far, but don't remember any of this roughness when I got my last one.

bop11

Go back to the dealer and drive another new one (not the loaner) and see if it is "Learning". If not, (the tranny shifts smoothly) get them to fix yours.

spyked

UPDATE for those interested:

I'm still just living with the issue. Have asked dealer to address it when I've had it in for service, but they claim nothing is wrong. I doubt I will keep this one past the warranty period...that 3-4 shift can be so unnerving under certain specific circumstances. It actually makes you wonder if a CEL is going to light up. Cant' bode well for long-term durability of the parts that are connecting so harshly.

Hope others have had better luck!

Otherwise the car is running fine, continues to be comfortable and fast for how heavy it is.

Mmr1

Take the dealers head mechanic for a ride, maybe they didn't duplicate the issue when they drove it.

Lazarus Long

I have noticed this in my '15, but I may not have driven as described. It is usually smooth, it may have shifted rough once. I don't remember which gear it shifted into.

The biggest annoyance for me is the throttle delay. The delay is improved in sport mode, but it holds 3rd for a long time.