Glyn M Ruck

Are both your cars pre 12/02?

Dingleberry

it appears that the '02 style TCU that i have cannot be flashed with '03 software.

i'm thinking about trying out the '03+ TCU, jerry@let seemed to have good luck with it.

Glyn M Ruck

Sorry - I did not know about the older TCU. I know that FrankW has a new TCU on his car - I wonder if he has this problem? My 1998 Merc must have had the older TCU but I did very low mileage - 6000Km from new - on that car before I sold it because the company moved me to Australia. I did not really get into the vehicle as a result.

Dingleberry

i just wanted to give a small update on my findings. i dont usually drive my car for more than 15-20 mins.

if i drive the car for more than 30 mins continuously, hard or soft, i get no clunks for the rest of the day! in other words, in the first 20-30 minutes of starting the car from stone cold, this is where all of the clunking appears to be happening.

i'm not sure what this means.

Glyn M Ruck

It must be the adaptive learning. If it really does not do it at all for the rest of the day it can't be fluid temperature related unless the car is never allowed to cool down.

evilsaint

Sorry to half necro this thread, but I'm of the same mind as many in this thread - it's all about the TCU or its adaptations.

My '02 is an early build (four dealerships have told me they can't flash the TCU) with 93K and at ~70K, no ATF/coolant contam. However, my car has (and exhibits on a very regular basis) ALL of the thump/jerk issues. 1500RPM from a start, the weird-*** RPM drop after cruising, seemingly excessive holding of gears quite often after hard acceleration, etc...

I've been reading about these issues since the start of my ownership and have pressed hard for work each and every time I've taken the car in for extended warranty service. Sadly, all it's resulted with regards to these issues is a free glycol test and a TCU replacement which seemed to fix everything. Actually, it *did* fix everything to a point where I had to completely re-examine my driving style... for 1400 miles. After that, the 1500 jerk came back and gets worse if I don't "flash" the ECU every 2-3 weeks. The RPM drop is there just the same as before, and I won't even go into the delayed or occasional mushy/neck-breaking shifts.

Again, however, I've had two different dealerships check out pretty much everything that delivers power to the ground past the motor and... it's all "fine". I've driven it, and been driven by, one of the senior techs *and* the service director (after a lot of careful *****ing ), so after replicating both of the problems for both of them, I trust that they really have performed all the non-invasive troubleshooting that they've talked about having done, yet I still have no concrete answers. Nothing strange in STAR, no CELs, no crazy metal grindings in the ATF (nor coolant, thank God), no strange sounds or vibrations - just these two weird-*** problems.

Anyway, I'm rambling away from the point I was trying to make, so here's the TL;DR version:

- Early 2K2, 93K miles, Glycol test at ~70K was negative.
- 1500RPM jerk and 30-40MPH cruising TC lockup RPM-drop since I got the car (57K).
- None of the problems at WOT or at least %75+.
- TCU replaced before 60K, fixed problems completely for 1400 miles, then came back slowly to full-force. Problems have remained since then.
- Engine/Tranny/TC/diff... are still all tip-top currently, according to two dealerships, but... the problems still remain

Next order of business - try and get the TCU replaced again by the same dealer as a rework and see if it temporarily fixes the problems again. C'mooon extended warranty, let's push for $7k

Dingleberry

excessive holding of gears after hard acceleration is part of the AMG package, surprisingly it's actually supposed to do that.

try to convince your dealer to get you an '03 tcu, do a search and you will find information on how jerry from LET got an '03 tcu into his '02 c32. he says it got rid of all these issues. i'm waiting for somebody else to try this before i blow away 300 bucks on a TCU

evilsaint

Well, sometimes it holds them normally and then lets up, but sometimes, usually when cold, it'll hold them until I blip the throttle again. Seems like every time I leave the parking lot at work, I have to goose it a bit to get it out of first. *edit* With no hard acceleration involved =(

Only $300 for a TCU? Can we replace 'em ourselves, or would it need rewiring? Stealership would probably charge an arm and a leg, but I wonder if FMU would be up to the task? I'd put $450 on the table for the chance at not having my spine further screwed up at 9/10 green lights

TemjinX2

tcu is bolt on...no rewiring needed. its under the passenager front carpet. probably a 15min install.

Dingleberry

yes, but to put an '03 TCU into an '02 car, it has to be specially coded by MB before being put in the car.

TemjinX2

you just need the star machine. I bought a brand new c32 tcu from pshek, so i assume its for a 04, trying to fix my esp problem. It worked fine in my 02, it didn't fix my esp problem, but it works the same as before.

evilsaint

That's what I was wondering. I figured the hardware was the same but the software would need tweaking.

What all did you have to change around using the SDS to adapt it to your '02?

TemjinX2

I would PM pshek about it. He's the one that did it for me.

splinter

Recently flushed and filled the gearbox with 236.14-specification fluid during the course of routine preventative maintenance.
Immediately noticed a marked improvement in lock-up abruptness during its initial leak check/fluid level verification shakedown cruise.
Better living through chemistry…could it be too good to be true?

After having driven with it in there for several thousand miles (with no adaptation reset), I’ve come to appreciate its gentlemanly light-load shift characteristics. WOT upshifts occur with alacrity heretofore not enjoyed with my 722.6. Its newfound upside is that it’ll bark ‘em on occasion. Never mind those SMG guys.

Although the torque converter’s lock-up abruptness hasn’t been entirely mitigated, it’s improved on the order of at least half, placebo effect notwithstanding. Not sure which friction modifiers and whatnot Fuchs blended in its Titan 4134 ATF, but their formulation most certainly works well in a modified C32.
Given that it’s also approved for use in MB’s latest DCTs was rationale enough to give it a go.

At >$150 for some 14 liters required during a complete TQ/VB flush -including the requisite OE filter, seal, gasket and sundry consumables necessary- it’s a damn sight less expensive than dicking around with so-called TCU/EGS or hardware upgrades. YMMV.

MIKESV8

you think the 55 is a better performing car than the 63? cool

Glyn M Ruck

Interesting squire. BTW Shell & Fuchs make all the Benz OE fluid now. I've just had my transmission serviced & the new fluid installed. My box has always been pretty smooth but now it's better (placebo effect notwithstanding) I used to be able to catch out the TC clutches now and again by snapping off the throttle & braking hard which would extract a slight clonk out of the transmission (taking up lash). This is now a thing of the past - amazing. The car has done that from new & I learned to drive around it. There is always some lash in the drivetrain on a RWD. The box now damps this out completely. I can only encourage people to change their fluid & filter every 60,000Km/38,000 miles. My used fluid looked pretty good. It was slightly darkened but clear & bright. Filter had done it's job & there was only the slighted hint of very fine wear debris on the magnet which is good going for the first change from run-in. Decided analysing a sample was a waste of time. Just did a quick crackle test to check for water/coolant. I have a Behr radiator so i had no worries there. I think my dealer thinks this oil guy is a nut when he asks for a teasoon & takes out his cigarette lighter to check the fluid for water.

Dingleberry

I too flushed my car with 14 liters but using OEM fluid. The torque converter still slams the same. At some point I might consider getting that TCU. The car only does the torque converter jerking for about the first 10 mins from cold start. After that warm up period, the converter stays locked up tight on light loads, meaning it doesn't let the RPM's rise slightly and then slam them back down as it locks up.

Glyn M Ruck

I used the 236.14 Genuine Benz fluid as I did not DIY.

crazypotato

I think lock-up occurs in 3rd - 5th gears only, and the OP said it is happening in 1st gear. Is it a few feature in later 722.6?

Glyn M Ruck

No

dontbanme

With all the research thats been done, you would think someone would be able to secure 03+ TCUs and program them for earlier models outside the dealership. I am sure many C32 owners would be happy to pay for this modification.

crazypotato

yes, gear 1 does have another lock up clutch. It is showing in DAS. There is a seperate adaptation for gear 1. I think the OP should give it a try to do an adaptation on the Gear 1.

Dingleberry

It's not just gear 1. During the first 10-15 minutes of each drive, if you let off the gas below 40mph and then get back on the gas. The converter lets the RPM's rise and then slams them back down as it locks up hard. Annoying...

crazypotato

Did you take a look at the Gear 1 lock-up adaptation in DAS? I think it is a temperate related adaptation. You have to start with the car <20C. and finish the process when transmission is at 80C.

Glyn M Ruck

Dingle - I think the only possible way around this issue is to get the newer TCU that can be reflashed. Frank has the new one & never complains with his C32.

If your problem was the good old 722.6 taxi hassle with the first to second one way clutch starting to fail it would bang through the 1st to second gear change everytime in S mode & not happen at all in C or W mode. (because the car would pull away in second gear.)