Dingleberry

check out these videos i took

here is the car about 20 seconds after being started:
http://www.youtube.com/watch?v=lvmWHmq_Hv0

here is the car about 2 minutes after being started. you can see that the last off/on throttle attempt that i do, the TCU locks the hell out of the converter.
http://www.youtube.com/watch?v=qQL2gpfV3K8

here is how i can bypass the clunk, i actually didnt give it a lot of gas, maybe 35-40%, that's why the TCU for a split second considered locking the converter but decided to leave it unlocked. at 50% throttle, the RPM's never even dip down because the TCU never even considers locking the converter at that level of throttle input. i'll have to take a video of that too...
http://www.youtube.com/watch?v=xJQUM-5tIkM

splinter

The cold start warm-up upshift delay and converter locking exclusion to aid catalytic converter light off is a known ‘feature.’
Another go with the incorrigibles at first light mañana. I’ll let you know how it goes.

Damn certain it’s a software glitch causing the jerk – a subject on which I can speak with some authority.

Glyn M Ruck

This problem seems confined to AMG transmission mapping. The only time you can catch out a standard 722.6 is if you are driving clumsily & accelerate hard followed by severe braking/speed reduction & you are slowing but catch the converter still hard locking. The tranny is effectively a few microseconds behind what you are doing & will lurch or clonk.

It must be said that this is aggravated by any undue lash in propshaft flex discs, splines, UJ, center bearing support or rear axle lash, splines, CV joints etc. Everything needs to be nice & tight & to spec. No lash will smooth the errant transmission behavior.

Dingleberry

i would like this "feature" to be on all the time

Dingleberry

is there any way to flash the TCU program off of a c320? i cant stand the AMG mapping for other reasons as well. there is no damn reason for the car to shift at 3,300+ rpm during non spirited acceleration (30-40% throttle) from stop lights. the acceleration is not even that hard, the engine barely has ANY load on it beyond 2500rpm. i can make the car shift at 2,500 by tapping the shifter over to the right (all while in D). i sometimes do this because it just annoys me to see the car rev to 3,500rpm, even though the shifts are still smooth.

why do you suspect drivetrain lash? there is no slop in any other scenario. the problem is that the torque converter is going from full unlock to full lock too quickly. there needs to be a prolonged period of "partial lock" to bring the RPM down gently before initiating a full blown converter lock.

Glyn M Ruck

Dingle - all I am saying is that drivetrain lash amplifies the problem from a lurch to a clonk. It is the drivetrain that clonks. Other smoother changes will not excite the lash into a clonk.

I see no reason why one could not apply standard C320 mapping to the TCU. My only concern would be, will it then behave in synch with the ECU. One obviously does not want to change a C32's ECU mapping. I don't know the straight answer to this question but it is certainly worth pursuing.

If it was me - as long as I had both versions of the software I would try it - one could always go back if you did not like the result. I am by nature a conservative but calculated risk taker - I would try it.

Dingleberry

I'm also really tempted to buy the LET high stall torque converter, since they claim that it completely alleviates the clunk issue.
https://mbworld.org/forums/3678022-post97.html

of course i would be fuming if i just blew away $1000 + my time to install it and the clunk was still there

Glyn M Ruck

I would try the remapping of the TCU first. But you need to find a dealer or Indy with the software for the ECU & TCU that knows what they are doing. It staggers me the number of dealer that can't even get Xenon present sorted without being told how. There have been no recent updates for the 722.6 - it is a pretty mature transmission.

The good thing with a SDAS & the full software is if you don't like it or it does not work you can just go back to where you are. Does your car behave like splinter's - no problem after a hard drive? Tells me that software can fix it if it works after the TCU has self adapted to harder driving inputs.

The LET converter is interesting. Do they run it with the standard AMG software flash? Seems this clonk is common.

PC Valkyrie

Dingleberry, I would be hesitant to flash a C32's TCU with a C320's TCU software.

The C32 has the AMG Speedshift features, which the C320 does not have. In addition to shift speeds being 35% faster, the Speedshift in the C32 also has the following features: active downshifting (the transmission will actively downshift with deceleration/braking so that you will be in a optimum gear to accelerate again), and holding a gear (without upshifting) when cornering at speed so as to optimize acceleration out of a turn.

If you find these features annoying to you when cruising around town, then simply drive in W (or C) transmision mode. In my C55, the tranny in C mode behaves like my old C240.....upshifts happen as soon and smooth as possible. It's really the S mode where the AMG Speedshift really shows itself when you are really pushing things and rpm's are high.

Unless you or your tech are really familiar with the TCU and its relationship to the ECU, I would not not reflash your C32 to a C320 TCU program. You do run the risk of screwing things up and getting error messages.

Glyn M Ruck

Does your C55's transmission behave like Dingle's?

Dingleberry

i have not heard of c55's having this issue.

maybe i can try a c55 tcu flash

Glyn M Ruck

Hey Hey hey !!! - We think alike That's exactly where I was going

PC Valkyrie

No. The only slight "jerk" (if you can even call it that), is at crawling speeds when starting off from a stop, I can feel the torque converter locking up when applying more throttle. Once locked up, it stays locked up from 1st gear onwards.

Again, don't know if you're going to throw error codes, as the C55's Speedshift has an extra "M" mode which the C32 does not have. The C32 has 2 transmission modes (W/C and S), while the C55 has 3 transmission modes (C, S, and M).

Dingleberry

Are you sure your converter doesn't unlock at full throttle? I think you may be mistaken.

I will try the c55 flash. If the car goes nuts I can just flash the stock tcu tune, right?

PC Valkyrie

Why do you think I'm mistaken? After full throttle application and then letting off the throttle in S mode, the car actually stays in whatever gear I'm in, staying with high revs, as the tranny wants to stay in the right gear for maximum acceleration. This happens on the streets and on the track for me.

The whole point of torque converter lockup is to eliminate the "slush box feeling", so that the car feels more "direct", like a manual transmission with no or little power loss through a typical fluid filled torque converter. In the C55, I think it does that fairly well.

Glyn M Ruck

Right! - the joy of software driven anything is that you can always "undo" & go back to where you started.

Exception - Microsoft Access!!!

Dingleberry

you stated that after 1st gear, the converter stays locked. i'm saying that is not true because if you go WOT, the converter unlocks for the gear change. My car also holds gears just the same as your car does.

i've read that the main purpose of torque converter lockup is for fuel economy

PC Valkyrie

Maybe I am misunderstanding your problem. I thought you meant that after going on the throttle, the transmission unlocks when you LIFT OFF THE THROTTLE. What I'm saying is that I have not found my transmission to "unlock" after I lift off the throttle (as seen by a rapid and sudden drop in revs even though the car's speed is not going down so quickly).

Yes, torque converter lockup does decrease fuel consumption, but the main benefit from a driving point of a view is a more direct connected feeling between your left foot and the car's response, as there is a direct mechanical connection within the transmission when there converter is locked up (more like a manual transmission).

OverDrive

Dingle try disabling your s/c for bit if you havn't already... I notice the jerk is when the s/c and the Tq locks up at the same time, When i turn off the s/c and just run as n/a its not bad at all, drives like a normal 320. This is what i have noticed with mine...

Glyn M Ruck

The prime reason the 722.6 & other MB transmissions have TC lockup is efficiency. This of course leads to fuel saving.

Being locked up like a manual is a worthwhile bonus.

PC Valkyrie

Hehe.....depends which press release you want to read. For the AMG cars, they sell it as a performance enhancement so that there is less drivetrain power loss and a more direct response with throttle inputs (which is valued when driving the car in a spirited fashion, especially on a road circuit).

Glyn M Ruck

Yes - I would expect AMG to put that spin on things!

Dingleberry

did you watch any of the videos? this is not s/c related.

Dingleberry

I had the car hooked up to STAR today. No transmission error codes.

ETC - Electronic transmission control
MB Number: 0305453032
HW version: 47.2005
SW version: 03.2002
Diagnosis version: 2/1
Pin: 11


so i'm guessing the dealer replaced the TCU for the previous owner in '05, and it appears that the software is from '02. STAR said that their were no updates for my TCU. STAR did not have any options to flash '03 software for my car. the STAR version is 5.8.7/02/2008


why would a TCU that was made in 2005 have software from 2002?

any ideas?

splinter

There have been a few TCUs from which to choose during the model run.
Don’t know that they were revised/improved in any substantive way, or if MB was merely consolidating their parts inventory.

Only the first four listed are ostensibly applicable to early build machines.





Curious footnote (which didn’t replicate during conversion to JPEG) regarding the #032 545 12 32’s SCN coding capability.







PC Valkyrie is almost certainly correct regarding the C55’s programming being incompatible with our earlier gearboxes. Pity.





addendum:
Attachment shows TCU/ECU interface and their control over the transmission.
Won’t be reverse engineering or hacking either anytime soon.