tiptronic woes

Hi all, I've a 1999 996 C2 tiptronic with about 100k miles on it. I had an engine rebuild (by one of the leading rebuilders) earlier in the year and while the engine has run wonderfully since, I've subsequently had a series of previously non-existent problems with the tiptronic. When I first got the car back from the rebuild I had a problem where I would occassionally get a clunk/bang from the rear of the car when accelerating properly for the first time after starting the car in the morning (i.e. not just pulling out of my parking space, but putting my foot down properly on the road). It feels very much like its transmission linked and seems to be around about the time that the torque convertor lock up kicks in when you are accelerating in 2nd gear (i.e. about 2,200rpm). It doesn't happen every morning, but when it does, it sounds troubling. When it does happen, its a once off and will then drive fine for the rest of the drive. My mechanic (a reputable porsche indy) checked the transmission and engine mounts and CV joints and found nothing. He then changed the transmission fluid (which had previously been changed about 30,000 miles ago). After the fluid change, the clunk/banging has become much less frequent, but still happens occassionally. However, more worryingly, there is now a new problem whereby once the car is warmed up and you are accelerating in 2nd or 3rd (say, with the accelerator pressed half way down), between 2k rpm and 3k rpm it the rpm needle will sometimes (but not always) move in surges. That is, it gets to about 2,200rpm and hesitates then lurches forward to about 2,400 rpm then hesitates again and then lurches forward to about 2,600 rpm, etc., continuing this to about 3,000rpm. Above 3,000 rpm it carries on acccelerating normally again. While it happens more often in auto mode, I can get it to do it in manual as well. I've ruled out the MAF by unplugging it and driving without it and the problem will still occur (although the tiptronic changes up to 5th very quickly with the MAF unplugged). I've also plugged in my Durametric and found no error codes (although Durametric 6 won't locate the tip module, while Durametric 5 will access it, for some reason). Any thoughts on whats going on here? I'm booked in to go back to my mechanic in a few days, but am getting worried about another big bill after having just gotten over the cost of the engine rebuild? Any thoughts gratefully accepted. Edited to add that when I first got it back from the rebuild the tiptronic was in limp home mode (i.e. flashing tiptronic light on dash and could only drive in auto mode). I hooked up my Durametric and reset an error code on the tiptronic (which I don't recall what code it was) and it solved the problem. My mechanic had thought it needed a replacement tiptronic control unit which he thought had been damaged when removing the engine/transmission, as his system wasn't picking up the code, but the Durametric solved the problem.

I replaced my tip at approx 98,000 miles as the input shaft bearing went out. I believe the 99 and 00 trannies had a design flaw as the tranny was NEVER as good and smooth as the replacement tranny is now. One thing that I noticed is every once in a while under abrupt, rolling acceleration the tranny would shift hard and "bang", in a way a $100,000 car should not. It only did it maybe a dozen times in the first 8 years I owned the car, and in hindsight I should have lodged complaints about it. The manual says no service to the tip for the first 100,000 miles. In my mind that means if it ****s the bed inside of 100.000 miles it should be under warranty. No dice. The new tranny was ESSPENSIFF!!!!!!!!! as the dealers do not repair them, but swap them out for a rebuild from ZF. In hindsight I should have let my indie do the swap, but I did not know enough about what was wrong with my car. By the time I understood there was something wrong with the tranny, there was a noticeable rotating noise, sounding like a "grumble" coming from the car, especially at idle. It was a very distasteful experience the result of which is I own the last two P cars I will ever purchase.

Good to hear she's buttoned up well. I bought my 99 C2 tip to have a 2nd 911 this one with auto trans. The tip shifts smooth. Years of enjoyment and many miles of spirited highway driving. No bangs ever. Serviced it at 92k. Now a low speed howling sound has me looking at tires wheel cv bearings. Regards,

Quotes source post: 9855672

Well it reads like and in fact your indy admits that something Tip related got damaged in the engine/tranny R&R job. I'd say based on what you report the person to talk to would be your mechanic who suspects something got damaged. You are owed reasonable care, skill and experience in the servicing of your vehicle. Apparently you didn't get this as to have one item fixed at the cost of having another item damaged during the repair is clear evidence you were not given the above. Thus unless you can work out a suitable mutually agreeable, err agreement, with the indy mech. I think you might have a claim of consumer fraud but check with the consumer fraud division in the county/region you live in for what is what in this regard. Consumer protection laws vary quite a bit and you need to know what they are for your particular area, for this particular situation. Before you do speak with him, if you want flat bed the car to a highly recommended ZF transmission shop in your area -- ZF transmissions are common in many cars and there a number of shops quite capable of doing a good job on these things (my local dealer tells me for Tip cars that come in out of warranty that if the customer elects to have the Tip repaired (if it is repairable) they remove the Tip have it delivered to the ZF shop for repair/rebuild then when done reinstall the Tip) -- and get this ZF shop's diagnosis or at least its thoughts on the behavior of your car's Tip. Sincerely, Macster.

Tip end-of-life issues Have a '95 911 Tip with 163k miles. I'm the original owner. The car and the Tip have been well maintained, mostly by my Porsche shop. No current issues with the Tip. (Had some significant issues when the car was fresh off the lot that Porsche ultimately fixed.) What I've learned so far is that when it comes time to "overhaul" the Tip that the best option is to swap out a rebuilt one from ZF. Not cheap but I'm OK with that. A few questions for the experts out there: 1. How long do Tip's last? 2. When they get ready to break, what do their last days look like? 3. Should my mechanic do the r/r/ job or should I let the dealer do it? Thanks John

Quotes source post: 9951206

A swap is preferred by some shops because it can collect a number of units and rebuild them all at the same time. There can be a problem with this though that I won't go into right now. A swap is also preferred by the owner because it gets his car back on the road quicker. But siometimes quicker is not always better. My mechanic friends from some time back always advised me the the best transmission to rebuild (or the best engine, the best alternator, etc) is the one from your car, unless the unit is not in a rebuildable condtion. If in your car's case if the Tip is just worn out but not worn in such a way the basic Tip foundation is no good that is the best rebuild candidate. But if a Tip suffers from say operation with low fluid level this can render the unit a poor candidate for a successful rebuild. A knowledgeable shop can advise you. For Tip longevity this is all over the map. Lke clutches, tires, engines, manual transmissions, CV bearings and so on how the car is driven, where it is driven, how well maintained it is, and so on plays a role in how long various systems last. About all one can do is do good car maintenance and along with this have the Tip fluid/filter serviced if not ahead of schedule at least on schedule and carry a rabbit's foot in his pocket. About that car maintenance: That includes things you might not directly connect with the Tip. For instance even if the engine doesn't apparenlty suffer any issues from overheating the Tip might. So keep the cooling system in good repair. For symptoms of a sick Tip these vary from odd shifting behavior, noises which can include groans, clunks, whines, to severe fluid leaking all way up to, or down to depending upon your point of view, to Tip shrapnel blowing out of a hole in the Tip case. Sincerely, Macster.

Good advice. Thanks Macster

I had a leaking Tip transmission, and the big issue on a rebuild was that Porsche does not carry the seals for this Mercedes-built transmission - and neither does Mercedes. However, a Porsche shop in Bath, England is now making these seals - Google and you'll find the name. I had a leak that my mechanic said needed a new tranny, instead we installed the new seal and it's been perfect for 1 1/2 years since.