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Hello all. I have a 2002 C4 Cab with tiptronic. I've been having slipping issues or what I believe are slipping issues. Well actually here is what is going on:
on hard accelerarion (wot) when the tip downs to 2nd gear, it doesn't shift into 3rd gear and as it accelerates in 2nd gear, it seems the revs won't go higher than around 6500 rpm and I have to ease up on the throttle to get it to shift into 3rd which happens really ROUGH with a massive bang and jolt to car.
Sometimes also the car car will not engage into 2nd gear when starting from a stop. The engine will rev and it seems like it's kind of moving but it's not and I have to let off the gas and switch to M and back to D to get the starting gear to engage.
I did a fluid service, not a full flush and also changed the filter. It got a little better but after a few hundred miles these symptoms came back. I used Pentosin ATF1 as that was what a shop used the last time the fluid service was done by previousnowner and I didn't want to mix fluids.
So so if I do need a new tranny can I get a C 2 tip and make it work with my C4 while maintaining 4WD or do I need to get a C4 specific tip?
Any rebuild suggestions or anyone have any idea what's going on?
I am 75% sure any 2002-2005 722.6 Mercedes tip will work. Part number on E-bay shows the trans being compatible between all models.
The 25% comes from me not being sure how the front wheels differential attaches in tiptronic. I did not see anything on my spare C2 tiptronic that would suggest I can bolt a coupling to it to make front wheels work.
Did you already try to reset the adaptation values of the TCU? Before looking into mechanical causes try first to reset those adaptation values so the TCU can adapt itself again to the specific characteristics of the transmission of your car.
To me your problem doesn't seem to me like a slipping problem but more the TCU getting confused with the input data it gets and not knowing what to do. The 6500 rpm you mention is the rev limiter of the TCU; in the lower gears it will not redline. Go and check if the transmission has any codes. Could well be a speed or rpm sensor not working properly anymore. Which could explain why the TCU is holding 2nd gear unless you back-off the throttle. The harsh shift has most probably to do with the adaptation values that it is unable to provide a smooth lock on the up-shift.
Did you ever perform further maintenance than the fluid and filter change? Did they read the codes in the tranmission? Actual values and transmission codes from the TCU are not available in Durametric!!! Maybe it is best to take the car to a specialised transmission shop. Get them read the codes. Maybe let them also check and clean the valve body and see if there is any wear on parts/sensors in there.
The 722.6 transmission is a common and well known gearbox. Considered as Bullet-proof. Certainly in the moderate torqued Porsches we drive. It is used till recently in many cars and models; Mercedes, Chrysler, etc. ... So most of the transmission shops do have experience with it. Makes that if you would need a (partly) rebuilt, the costs could be reasonable. However I will certainly ask around and go for a second and even third opinion before looking into the rebuilt scenario.
For the ATF, no idea about the Pentosin probably it is a good oil. Possible newer alternatives are those ATF which fall under the 236.14 specification such as Mobil 134 or the Fuchs Titan 4134. They will do the trick. OEM such as Fuchs Titan 3353 is also fine but the newer 236.14 fluids are specifically designed for torque converters with lock up clutch, the 3353 at that time was not. Although it is a good ATF to use.
One more question. Do you have any performance mods on your car? The TCU is a complex thing and it communicates with the DME and gets a lot of values from it to take into account the shifting. Sometimes performance mods cause some of these values to go 'out of spec', at least for the TCU. Because of this it can start acting up causing a wide variety of apparently non-related problems.
I just bought the car in Jan sso I think no mods that I know of. Come to think of it, these issues don't happen in manual mode or at least that's what I feel. I'll have to really pay attention and see if they happen in manual mode. If not it sounds like it is the computer and adaptations. I'll reset adaptation values. I have a durametric and I think I can reset adaptation values.
I haven't done any other maintenance to the tranny. The previous owner did have some seals of the tranny replaced as they were leaking. This required removal of the trans and it was sent somewhere to have the work done. While they had it out they did IMSB, crank seal, air oil separator. That was at around 70k miles. The now has 102k miles. That is also where they used the Pentosin ATF1.
Ill call around to some tranny shops. Thanks. This is very helpful!
Be aware that for the 9x6 models the functionality of durametric with respect to the tiptronic module is very very limited. The only thing that is there is the adaptation reset. Even the tabs 'Information' and 'Identification' do not show any information at all, even an error.
The fact that you cannot access the 'actual values' does limit the possibility to analyse transmission problems.
So I was able to take the car out and drive in a spirited fashion in Tiptronic mode. It shifted and performed beautifully. The only hiccup was shifting between 2 and 3 on hard acceleration. The shift was noticeable and slightly rough. But other than that it performs great.
Also I'm returning the durametric. It is not very useful for me and my 996. I'm sure it's a great tool for others but not for me. Glad they take returns.
So the tranny died today. It will not go into reverse or 1st gear and when starting in Second it barely moves forward. Just slips away. So bummed right now.
So so can anyone tell me if I can get C2 tip and have it work on my C4? Can I simply remove the front drive shaft from the old tip and mount it to the c2 tranny?
There are lots of C2 tips for sale for around 1500-2000 bit no C4 tips. Thanks!
Hey all. I got the tip out yesterday. It's going in for a rebuild. I think a C2 tip would work because the front end of the tip where the center drive shaft connects is removable and I'm sure one could remove it and bolt it on to a C2 tip. But I'm going to pony up and take it to www.peterschmidtransmission.com for a rebuild. Should have a like new trans in by the end of the week.
I had your hard shift symptoms back in 2008. C4 had prox 100k on it. It got noisy and the diag was the input shaft bearing was toast. I had a local dealership deal with it. I would NOT do that again. I am STILL kicking myself for not having my indie deal with it.
Back then there were no rebuilts (available so I was told) and Porsche did nothing for me as the car was 8 years old. I swapped out the tip for a reman one. It was an expensive experience.
The dealership installed the tranny bolts so over torqued, when I went to have the done, they had to cut the bolts with a torch to get to the ISB without hurting the block.
I will be interested in hearing what your tranny diagnosis is........
The tranny is dropped off. Dietre Schmid was there to greet me as well as Dee Dee, the amazing lady in the front office. What an amazing place they have! So clean and organized, just like you'd expect from German automotive experts and hundreds of tiptronic transmissions neatly organized and shelved.
Deitre says that he will take pics while doing the rebuild and let me know what went wrong. Once he is done, I'll have an essentially new transmission. Comes with a 2 year unlimited mile warranty and it will be nice to know that I shouldn't ever have to worry about the tranny again as long as it is maintained properly. I should know by Friday what happened to it and have it back next week.
When I was looking around for a rebuild of my transmission I asked several specialised shops.One of the shops was in Germany. The owner used to work for Mercedes and he told me he was actually part of the devision who designed the 722.6 transmission. He told me the only sensible thing they could modifiy to improve performance of the tranny was that they improve the oil pump capacity. This results in better shift performance due to an increased pressure out of the valve body. Also it causes a lower wear of the transmission. With a better oil flow the transmission temperature will be also reduced. All improving lifetime and wear.
Maybe good to ask if they are aware or have experience with such mods. As they are opening up the tranny it would be sensible to do all possible improvements available.
Here are some pics of the RMS and IMSB for anyone interested. I was surprised to see how clean it was back there. No oil at all. The RMS has the square indents which I've read is the updated version. The IMSB looks to be an LN Engineering one. These were updated about 30K miles ago and it still looks solid. I also think I found the Air Oil Separator and it too was totally clean. I've included a photo of what I think is the bottom of the Air Oil Separator. Can anyone confirm this for me?
As far as upgrades go when doing the rebuild, I'm going to go with stock. They told me that they would update any parts to the latest spec. I guess if the oil pump will be replaced with the latest spec than I will get that. There are no performance updates being done. I just wanted a factory spec.
Will post pics of rebuilt tranny when I get it and I'll also try to get better pics of the tranny install.
Flexplate is off and is surprisingly clean in there.
Close up of the crank and RMS. Looks to be an updated version.
IMSB. I think there is an LN Engineering stamp on that.
I think that thing with the 90* elbow on the bottom of it is the Air Oil Separator. If it is, it is totally clean of oil which is nice. This was changed around 30K miles ago.
04-12-2017, 02:47 AM
C2 tiptronic work in a C4?
