I think I would try to find the closest Porsche mechanic and get the transmission serviced. Hopefully somebody in Arkansas can point you in the direction of a reputable mechanic who will ease your mind a bit.

This whole thread is a bit odd to me. The original poster from 2010 had three different mechanics, including a Porsche dealer, tell him that he needed transmission service, and he doesn't know what to do??? Get the transmission serviced for crying out loud! I'm not sure what kind of magic he was hoping to find here...

 

Both of the mechanics I went to were certified Porsche mechanics. I had the trans service with no improvements. I've found while looking on the web that several people are having this issue but no one has an answer. Its weird because there are no codes showing, car drives and shifts fine, its just annoying as hell. Guess were all just hoping someone will give us the miracle (cheap and easy) fix.

 

Interesting...

Hopefully if it's a common problem, you can find a fix.

 

Does it happen in reverse?

 

I have a '99 cab tiptronic with 92,000 miles with the same (or similar) problem. In every gear under 2,500 RPM's, the tach jumps up and down 200 RPM's every second or two. It feels like the torque converter lockup clutch is engaging and disengaging until 2,500 RPM's, and then it stays locked and everything is fine. No warning lights or codes. The car is currently at Jackie Cooper Porsche in Tulsa. They're checking it out now but have not determined the cause of the problem yet. I'll post any results that they come up with.

 

You say at 2 that the fluid LEVEL is good but what about the actual fluid itself. Is that the original fluid? I don't know but fluid of all kinds must go bad at some stage. Can it be completely changed for new fluid? Would that solve the problem? That seems like the obvious first move. Probably a DIY job. Its easy for a mechanic to say the fuel pressure is good. But is it? I wouldn't trust a mechanic as far as I could throw him from what I have learned since getting this car. I changed my gearbox oil today and that was pretty easy to do. Mine is Manual. It can't be much harder to change (or can it).......Read up on the best oil for the job and try it.

 

If I may be so bold as to weigh in when I personally have a stick shift? Please? First, I'm not a mechanic by trade. Second, getting advice on your transmission from an Aamco or a run of the mill trans shop is like bringing your Rolex to Walmart to have the battery replaced. All kidding aside, find a shop that has a dyno (4 wheel dyno if you have a 4 or 4S) so that they can put your car under a load. They can then do an emissions test to see what comes out of the tail pipe when it starts to complain. If the numbers aren't normal, then you have an engine problem. It's possibly the O2 sensor BUT it might also be something as simple as a rotten vacuum hose! With the age of the car, that is a very real possibility. I joked a bit but I truly hope this proves to be helpful. Alan

 

I have a 2002 4S which was having increasing frequency of transmission issues over the past 6 months (until a month ago when I got it fixed). The dealer had no idea what was wrong because there were no error codes and wanted to replace the entire tranny. My car would become jerky in certain situations like slowing down on an exit ramp getting off the highway or downshifting through 3rd gear. The car ran well for years, but then problems became more frequent and recently unbearable.

I'm not sure for the 99, but there was apparently a service memo issued by Porsche regarding a known TCU (Transmission Control Unit) issue, at least in the 02 4S. The new updated unit has improved mapping and fixes some dysfunctional programming. The part runs about $1750. The TCU is located in the backseat on the passenger side behind the panel. That replacement with some new transmission fluid and my car runs better than new!

 

The dealer in Tulsa said they found quite a bit of metal shavings in the bottom of the pan when they were servicing the transmission. They went ahead and flushed the transmission and torque converter and test drove it, and the problem went away for a short time but returned. They said it is time for a new transmission.

 

New from porsche will run around 8-9 k installed. You can get a rebuilt one and gamble. You can get a used one for a few k and gamble, but should be ok. If low miles. You can send it to Freddie's transmissions in Denver and will be around 5 k. Those are the options as far as I am aware. I ended up getting a new one from porsche and installed, plus taxes plus transmission mount (might as well) it was 9.5k. A couple if years ago and not throug dealer but through my Indy. Interestingly enough, e got a brand new one from the dealer, installed it.... And it was defective. He had to take it off, ask Porsche for new one, and he did eat the cost of replacing it. Porsche did not cover his labor to replace their defective unit.

 

Unlikely that a Porsche, at 90K, hasn't had some, or most, of the services done. Original owners certainly take care of scheduled service (too much invested). Usually only later owner's who neglect maintenance and pass it on to future owners. My advice is have everything done and protect your investment. That is what should be done with any used car purchase.

 

 

You will need a Durametric to read transmission fault codes. A regular ODBII reader won't do it. A dealer or transmission shop will have diagnostic tools that may help. My 2000 Tip is slipping a bit in 4th gear. They told me to live with it for now but that I'll eventually need a rebuild for about $6k. An alternative would be to buy a used one for about $2k but that can be risky.