Acapulco Bill

While perusing the bimmerboost.com website for solving an electrical issue with my E31 V12, I came across a thread about an upgrade for the TCU and valve bodies for the C63:

http://www.bimmerboost.com/content.p...nverter&page=1

Upon writing Weistec to inquire if the 7G 722.9 transmission in the W204 C300 and C350 could receive the same upgrade, this answer was received:


William,

I apologize for the late reply. I wanted to get a solid answer for you on this. The transmission in your C300 is a 7G, however it is torque converter based, and not MCT. We do have a valve body upgrade that is available for the AMG 7G (nearly the same transmission) and we also adjust parameters in the TCU to help with performance. I have asked our engineers, and they said this modification can be done to the C300-C350 valve body as well. The cost is the same as our AMG valve body. Please view the link below. Thank you and let me know how I can assist from here.

http://weistec.com/7229vb.html

Best Regards,
Anthony - Sales at Weistec Engineering

If you read the Weistec website about this rebuild and the logic behind it, for this reasonable price think of this upgrade as costing half what a major transmission rebuild will eventually cost, after the plates, for lack of proper pressure, wear themselves out due to slippage.

As I have posted on other threads my disappointment about the 7G transmission’s sluggish performance (e.g. lame, s**ks, downright dangerous in overtake situations, etc.), and the reason why this auto enthusiast purchased a FORD within days of taking delivery of my new 2010 C300 Sport was because of the of its unspectacular “driving experience”, The W204 has sat now in the garage unused for months. Maybe I drove it 4 times in 2011 to keep the battery from going flat.

So this TCU/valve body upgrade and the Kleemann ECU tune (both can be done by the same motorsport service in San Diego) are programmed for the day my warranty expires.

Hope some other W204 owner who feels that they are just plain stuck with the terrible 722.9 7G transmission can make use of this fantastic-sounding rebuild. Anyone else agree?

frogs9497

I suppose I'm confused as to why you purchased a C300 in the first place (with all due respect).

Shifter

Ya, you have a C300, which means the trans is programmed to shift smooth and soft. No where close to how a C63 shifts. (even non MCT C63)

Acapulco Bill

@frogs9497 - I had test driven a C300 Luxury in San Diego before I bought the C300 Sport in Mexico. Since the test drive was in the city, short and without many places to accelerate it flat out, I though the W204 was fine. I am even sorry that I have the Sport, the ride in the Luxury is more my liking. (Not the looks or the interior, I am crazy about the design of the Sport W204).

Frankly I expected the performance closer to the BMW 3's we had (a 330i and a ZHP, which is just fantastic performance and spot-on nearly instant shifting for a 3.0L engine). This will be a welcome fix, and along wth the Kleemann extra horses, should put the C300 performance well above the levels of the 3's.

@Shifter, so this means you agree the 722.9 7G in the C300 and C350 is LAME?

Shifter

Well, that depends on what you consider lame I guess. I've driven hundreds of them, and they shift smoothly and uneventfully, especially since most start out in second gear.
Programmed more for economy and comfort I suppose you could say.

Acapulco Bill

@Shifter: Actually the 722.9 transmission is capable of excellent performance, fresh out of the box, for a few hours. It is the incomprehensively stupid "Adaptive Learning" part of the TCU that causes the 7G to "learn LAME".

When I had the C300 in the MB dealer for its mandatory 1 years service (at about 3000 miles), I asked for the mid-2010 TCU firmware upgrade to be installed (no other error codes appeared on Star). WOW it was just fantastic, the downshifts were prompt and the upshifts powerful. I was so pleased.

But after driving around two days later, with stop signs, city traffic and lights, the TCU "learned" that the driver was as a "little old lady going to church". If you, Shifter, state that after driving "hundreds of them" and they are all the same, means that everyone else's TCU "Adaptive Learning" has ALSO classified them as octogenarians and shift lethargically.

So a first option would be to lobotomize the TCU by blocking the code that "learns" the W204 is being driven by a garden slug, and restore the firmware to its original fresh state. The Weistec solution with the upgraded valve bodies along with a TCU remap is a great solution, as there is nothing basically wrong with the 722.9, its just this stupid "learned LAMEness" that makes the shifting so slow and dangerous. Even in Sport or M mode with paddle shifters, downshifts take about two seconds manually, and upshifts also about 2 seconds from the time the accelerator is floored (worse now that since 2011 there is no accelerator downshift switch). How many are tired of being in the "Comfort" of a transmission that thinks its a washing machine? "No wait, thats not right. I'm not a washing machine, I AM a transmission. hmmmm.... Maybe I should shift?"

Shifter

LOl, I get your point, not arguing with you, clearly you want a more sporty shift pattern.

Here is a bit of info you might find interesting. A C300 valve body, and a C63 valve body are the same. Same part #. They come blank, no programming in them. They then need to be programmed when installed, and this is where the difference is. So, If a C63 trans (pre MCT) can perform so much better than a regular C300, all you really need is a software upgrade weistec can offer you. Your not going to be making much more power so hardware(the valvebody itself) will not need to be changed.

Acapulco Bill

The point of Weistec having success and sales of this C63 upgrade with new valve bodies is to apply more pressure to the plates. The Weistec website on the 722.9 offers some interesting reading. If someone offered just the TCU lobotomy and firmware restore, that of course would be the most reasonable and economical solution. Weistec states that there is more than that, and that upgrading the valve bodies opens a new horizon of 7G performance.

Acapulco Bill

Even Top Gear complains about the lame 7G performance in the C63 Black series:

"The only fly in the C63's wingy ointment is its slow-witted seven-speed semi-auto 'box, which clings onto gears just a quarter of a second too long, sending you clattering into the rev-limiter with a machine-gun tak-tak-tak."

In a C300 or C350 the shift just hangs and hangs. "Slow-witted" is saying the reality too kindly. Smash the accelerator to the floor and you get kind of a cough and about 2 seconds later you can hear the transmission still thinking. Meanwhile you have lost the opportunity to pass, or worse still, you are facing a semi that was previously a safe distance away.

http://www.topgear.com/uk/photos/top...8-29?imageNo=5

kevink2

First, nice work getting the TCU/valve-body upgrade in progress. I personally enjoyed a "shift kit" on my Olds 425 ci Dynamic 88 with a turbo-400 trans with adjustable turbine blades.


In the interim, can this firmware upgrade be done by the dealer now? I know that if you then drive like an old gent, the sluggish shifts will return.

Also, does disconnecting the battery, and pressing the brake pedal, clear the TCU learnings?

I assumed these were the TC plates. Glyn recently posted about steady state TC lock was about to change to 100%, vs the prior ~98%. Personally, I never detected TC slippage on the 08, no evidence of rpms rising faster than the mph's. Is this plate wear due to slippage during shifts, or during steady state TC lock mode, which would be helped by the new 100% lock ??

.

dfordham

TCU reset is covered in other threads. Found this procedure in one of them:

1. Turn the ignition key to the on (not start) position.
2. Press the gas pedal to the floor and hold for five seconds.
3. Turn the key to the "off" position (don't remove the key), then release the gas pedal.
4. Wait at least two minutes for ECU to reset.
Hope that was helpful.

It says ECU, but it is actually the TCU.

Haven't actually tried it but if it works it should serve as an interim solution.

Regards,
Don

kevink2

Thanks DFord, but that is the proceedure to reset the gas pedal's wide open and idle positions. When the "secrets" were written, it was thought that the proceedure did a lot more.

.

dfordham

OK, thanks. Like I said I have never tried it.

Regards,
Don

Cy3

I like to think of my transmission like a suggestion box, where I angrily write down on a slip of paper what gear I would like next slide it in, wait a day or two for the powers that be to mull over my suggestion, process it, consider it, vote on it, then make a decision. Regardless of whether I have a semi-truck bearing down on me or not.

Acapulco Bill

Actually, kevink2's Post #10 has made me wonder if it was just slippage that makes the 772.9 7G transmission so sloppy and slow, or if another reason was responsible. Another thread somewhere mentioned a clunk shifting automatically from 3rd to 4th gear, made this subject "curiouser and curiouser".

The as-always-excellent guidance from Glyn M Ruck in the https://mbworld.org/forums/c-class-w...ce-thread.html

eventually led me to this source:
http://www.scribd.com/doc/49188099/M...smission-722-9

Now you can start by reading all 79 pages of this MB document, as you humble servant did - twice - but the important page is #35, the charts are annexed below. Basically what the left graphic shows is that on all sequential gear upshifts, you flop a "B" valve/brake or a "K" valve/clutch or both. However, the quickest way to cause a change is not a shift "within" the "B" valves/brakes or the "K" valves/clutches packs, but when the pressure on a "K" valve/clutch is released to pressurize a "B" valve/brake or vice-versa.

Therefore the right-hand graphic on page #35 demonstrates that your fastest downshifts run from 7th to 5th, then from 5th to 3rd, then from 3rd to 1st. As would be your fastest upshifts, but the 7G logic never upshifts two gears.

So which gear is left with a "double-change-sequence"? Fourth gear, so the change from 3rd to 4th may be subject to a clunk or a thud, especially if the throttle is released during this transition, which changes two brakes and two clutches to change at the same time.

Now after driving my Bimmers daily in another country last week, where the transmission shifts are nearly instantaneous even on the hardest acceleration, in a similar transmission with three valve/sets of brakes and three valve/sets of clutches, a ladder configuration could be engineered so that every brake release was coupled with a clutch application, and then a clutch release with a brake application, so that either upshifting or downshifting, the action would be near instantaneous.

The limitation here is that there would only be six forward gears instead of seven, logically, as the BMW transmissions are (the latest ones of course are 8-speeds, also logically). The limitation is that only a PAIR of disks are run in any one gear, instead of three as in the 7G.

This probably means for those users who purchase their Merc (any with the 7 speed transmission) for waffing down the highway with a minimum of fuss, and maximum of fuel economy, these built-in slow shifting sequences are not an issue. However for those interested in more aggressive shifting, the stock 722.9 just is not going to cut it. Period.

Simply by causing more pressure in valve/brake B2 and valve/clutch K3, which are locked for almost all gears except 4th as noted above, will reduce slippage and provide changes between the "B's" and the "K's" with more bite.

Arranging for B-to-B or K-to-K changes to happen faster will then again make this transmission perform more lively. So it is possible that the "hope" provided by Weistec can improve things.

Although with BMW's ladder arrangement that always changes a brake for a clutch and vice-versa, both sequential upshifts or downshifts take almost no time at all, and grab aggressively, always.

Now about the torque converter slippage: Page # 16 shows a graphic for the conditions where the convertor is locked or allowed to slip. Then in the Appendix on Page #78, (although it is a relative guideline) one can calculate the % of torque convertor slippage which is about 96% at normal throttle settings but almost no slippage (99% to none) at 100% throttle. I can't understand why, maybe someone can explain this.

So I understand that the 722.9 7G transmission just has built-in lameness. Guess we will just have to learn to live with it, or get a radical upgrade that makes the best of a bad engineering compromise.

Acapulco Bill

ANN Furthermore, here is a link describing the blatant stupidity of the Adaptive Learning TCU scheme, which to me serves NO purpose, as it is just impossible that one ALWAYS drives like track day in normal city or highway driving. As soon as you slow down to park the car, the Adaptive Learning "learns" you are 90 years old and stores this info. WTF. You tell me.

http://www.thetruthaboutcars.com/200...transmissions/

Acapulco Bill

In addition to the above mechanical and adaptive defects inherent in the 722.9 7G transmission, annexed is MB's explanation of the "thought processes" that the TCU much negotiate, before it "decides" to initiate a shift, even though the change is manually commanded through the console shifter or paddles on the steering wheel.

Although the design and engineering of the 722.9 7G transmission are prioritized to extract the best gas mileage, the consequent performance makes the W204 sedate, unsporty or just plain lame to drive.

kevink2

Thanks for reading the referenced link twice. I think you can read it like a fiction novel, where for me it's like reading a physics text for the first time ! I will read up on this more when I get a chance.

But from the link you used, they have steady state shift diagrams for each
gear, so given that it's steady state, it would logically be the same for comfort vs sport modes, correct?

And I take it that the clutches they had talked about wearing, are the trans clutches, not the TC ?

.

Acapulco Bill

@kevink: The"steady state" diagrams as you call them, are the same for both C and S modes (and for M if you have paddle shifters as in my Eurospec C300 Sport). The difference is that the TCU has a separate set of parameters for upshift points, the S mode of course redlines under full acceleration and C mode looks for shifts inside the torque band to keep gas mileage efficient.

The TC has no lock up modes except in 1st gear.

M mode of course turns off the TCU upshift routines beyond the selected gear completely. So if you are in 3rd the TCU will keep the 7G in that gear even at the redline. As you stop it will downshift to 1st, and at take-off will go with S mode shifting until you reach 3rd gear again, where it will stay.

Took out the C300 this morning just to keep the battery from going flat for the first time in a month, preferring to drive the fabulous Ford everywhere except on long trips. I paid attention to the shifts into 4th gear, and yes they are slow and cause the vehicle to lurch, result of the double-duty changes between both B and K plates. Driving in S mode around 50 MPH, it sloshes in and out of 4th as a water-filled balloon bouncing on a pillow. Anyone else notice this?

Still looking for a way to lobotomize the Adaptive logic on the 7G, a totally stupid idea that makes no sense at all. Can anyone offer suggestions to eliminate this plague from our transmissions?

kevink2

By steady state, I simply meant independent of the transient behaviour related to shifts.


I believe, from Glyn, it has at least 98% lock up in all gears in steady state operation, low to at least moderate loads. Glyn mentioned that MB would be going up to 100% lock in all gears, perhaps when the plus version of the 7 speed comes out. Watching the tach shows there is no jump in engine rpms if you increase the gas 20% in any gear. I'd say an old Buick I drove a few times had no TC lock-up in any gear. The first cars with TC lock-up were limited to top gears only, ie for on the highway.


In the 2008 C300, I never noticed what you have described. If in a gear following a car I needed to pass on a 2 lane road, I simply put a bit of extra load at the pedal, then punched it about 30% and I got a decent downshift in less than a second.


.

Acapulco Bill

Apparently more and more are very aware. Its is MUCH more than a second and downshifting with paddles sometimes takes several seconds. Same in the brand new CLS550 test driven a few days ago at a MB dealer with just 20 miles. Getting back into the BMW was just such a THRILL in comparison.

I would like to make a video of doing full pedal depression for a second - to none, then repeated, etc. There is NO response from the transmission at all. However just after the TCU software update it was just fantastic. Two days later the Adaptive learning had gone back to being LAME again.

Another recent solution for the problem that many third party tuners are profiting from:
http://luxurycarmagazine.com/a-solut...onic-troubles/

cdonner

I had a 2009 C300 Sport with the manual transmission and I loved it. I bought the car at the end of the lease, gave it to my wife, and I got a 2012 model year where, alas, the manual transmission was no longer available. I agree that the sluggish transmission is outright dangerous. When I sit at an intersection and have to merge into traffic, the delay from when I step on the gas until the car actually moves is agonizing. I don't think I want to continue driving this car once the lease is up.
Is there an actual solution to this that someone has implemented and can recommend?

Acapulco Bill

Will be taking the C300 to the MB dealer for an A service and they are interested to see if the "learning" software of the TCU can be disabled, do the same update as before, and hope it sticks. This will be in about 60 days and the results will be posted..

alsyli

Yes, it's called pushing the "S" button. The transmission is horrible in "E," but it's fine (if still somewhat slow) in "S" (even if it seems to degrade fuel economy).

If you're finding that maneuvers in "S" are still "outright dangerous," then perhaps you should consider that the maneuver you are attempting is simply ill-advised.

Acapulco Bill

@alsyli: Even with the "M" Button (you DO have the "M" button and paddle shifters, alsyli, right?) pulling on either shifter requires a two-second or more wait for some kind of response from the 7G transmission. Even in the C63 AMG. Read the recent Top Gear review of the C63 Black series, its their only complaint.

And yes it IS "outright dangerous". My minivans' transmissions takes less than half a second to downshift when floored, the Mercedes' accelerator can be floored - released - floored - released at 2 second intervals and absolutely NOTHING happens. Out of the 10 vehicles currently owned with automatic transmissions, the W204 with the 7G is the garden slug, worst by far, even to the languid performance of an underpowered 4-cylinder Honda. Which is why the C300 Sport just sits in the garage with its battery going flat.

The transmissions in the three BMWs owned put the W204 to shame, and the two with 3.0L 6-cyl. engines are easily 1.5 seconds faster from 0 to 60 than the 3.0L 6-cyl. C300 Sport. That's a FACT. And despite the M272 V6 engine having more torque than its BMW M54 V6 counterpart, any magazine or internet comparison review will cite the 7+ second C300 time vs. the 5.6 second or LESS time of the (old) 328i/330i. ALL of this time difference is due to the slovenly slow shift times of the 7G transmission.

"Outright dangerous" is EXACTLY what the 7G is. Right on, @cdonner !!!!!