E63 violent 2-1 downshift
 

I'm experiencing what could best be described as a jolt on downshifts from 2nd to 1st. It only happens in sport mode. As I understand the car only downshifts to 1st in that mode. The jolt, which feels like the car jumps forward (some have described as feeling like a car bumped into the back of the car) feels stronger when the car hasn't completely warmed up. I have searched the forum and have read about ECU updates and a myriad of other problems that could cause this. Apparently it's pretty common. Can anyone chime in about their experiences and how they may have resolved the issue?

There is a TCU update that resolves this apparently. You need to go to the dealer and they should be able to flash your TCU/ECU. I believe they update both when performing updates. Expect to pay an hour of labor.

Thanks Farkis! I see you own an '07 E63. Did you run this update with success?

I have not but want to. I don’t have the hard downshifts like you are experiencing but my car does start off in second gear even in sport mode and I know the update fixes that issue as well. In general, I’ve read the update smooths out shifting.

Did this issue just start or has it always been like this?

How many miles on the car?

Mine will occasionally give 1 harsh downshift when cold. I'll have to talk to my mechanic and see if he knows about an update for that.

It's happened since I acquired the car, which was just a few months back.

80K miles on the car.

In the name of science, I will spring for the TCU update--provided my local stealership doesn't price gouge me on labor. It seems to me it's the most reasonable suggestion (thank you, Farkis) to fix this problem. I've seen that others have replaced solenoids and just about every component of the transmission--and many without resolving the harsh downshift issue fully. Someone mentioned the TCU update should prevent the car from downshifting from 2nd to 1st altogether in sport mode. That gives me a reasonable degree of confidence that this could fix the problem. Stay tuned.

I'm going to check into this, as I'm starting to have lagging engagements from 1-2 when accelerating. And 3-2 hard engagements when downshifting.

I have the same issue when cold that when coming to a stop its a hard downshift like being hit from behind; 2009 E3 w/ 81K miles; and my understanding reading the several forum posts on this is to change out the one solenoid (TCC? can't remember the name right now); and a flash to the TCU will not help.

My car does it as well when cold. My understanding is that it's normal. If you don't want to deal with it, leave it in comfort until warmed up.

Thanks, yes I read about that also. The thread I read was about another model of AMG, but apparently it was very effective. I received two quotes today for $220 to update the ECU/TCU. At that price, I'm not sure I want to be the guinea pig here. I'd be pissed if it didn't work.

It may be common, but there is nothing normal feeling about that downshift. It feels almost violent and can't be great for the transmission.

Ok, so I'm going to try having my indy mechanic replace the PWN (TCC) solenoid, part 240 270 17 00. Thanks Anomadtoo, for bringing this up. It looks like the most reasonable fix to perform first. Plus there are several members who claim that this completely remedied the issue.

Btw, regarding the TCU update, apparently this only masks the issue by making the 2-1 downshift less frequent. Plus I've read varying results from this update. I'm not dropping $220 on a "maybe" until I try replacing the solenoid.

There is literally a service bulletin that describe the symptom you are experiencing and a TCU update that fixes it (prevents 2-1 shifts until the car is stopped). This and addition to smoothing out shifts in general.
https://cimg2.ibsrv.net/gimg/www.mbw...978148165.jpeg
If you have always had this issue, there is a great chance this would solve it. And for the price, This is the best place to start imo. Now if this had just started, I would think the software update wouldn’t help.

$200 seems a little high to update but not insane. Did you go to the dealer? In my experience, my Indy charged more than the dealer for updates bc they needed to pay more for them I believe.

Also, the model of car doesn’t really matter as long as it’s the 722.9 tranny around the same years as far as I know—so reading about different car models isn’t necessarily leading you in the wrong direction.

Good luck

I'm going to try the solenoid first and see how it goes. If it persists, I'll do a TCU update. This is a dealer price of $220/hr in labor, which I think is a little over-the-top for a software update that should have been administered properly from the beginning.

My ML63 had a violent downshift from 2nd to 1st as well in S and S+ and was told by dealer it's normal. Thus, I resorted to driving it in C mode most of the time until recently I had a Eurocharged tune done. It completely got rid of the violent downshift both in S and S+ mode. Only on very cold mornings and the engine super cold that it'll still exhibit a slight hard shift. I asked Eurocharged if the tune had anything to do with the shift and was informed that the tune changed the shift points so it may have gotten rid of the violent shift. Thus, I can only assume that it's software related and not necessarily hardware. But who knows, I'm no car expert....

I think the issue may be with both. I believe the software update negates the hardware issue by eliminating the 2-1 downshift in sport mode--which is probably why your E/C tune remedied it. From what I've read, the hardware issue may be caused by the PWM (TCC) solenoid. I'm going to replace the solenoid and I will post whether it eliminates the jolting downshift.

Any update on this?
It would be good to know what was done and what the results are on this.
Thanks.