1999 996 Tiptronic trouble. I'm at a loss!
 

I am afraid I don't know what is wrong. I have been to an import mechanic, the local Porsche dealership and Aamco. All say it is the transmission. The bad part is there are no codes showing. When I am driving between 1500 and 2500 rpms there is a surging. It does it in each gear. It is also worse as it is pulling a grade. I am completely lost on what to do. I would appreciate any help or advice?


89,000 miles

TESTS - Porsche Dealer -.
1. He did a 89757 internal malfunction test with piwis tester - none registered.
2. fluid level - good.
3. tested MAF - good
4. tested for power and ground on TCM module - good
5. removed torque converter lock up wire and test drove- good
6. checked fuel pressure - good
7. no codes in vehicle
8. solenoid circuits are intact and complete
9. No Tiptronic codes
----He said the main line pressure for transmission fluid control loses pressure on and off which is a sign of a weak solenoid.

Miles
 

How many miles do you have?

Did you check O2 sensor?
It's a possibility.

89,000.
No I didn't try the O2 sensor, because all three say it is the transmission; however, I am open to about anything now.

Did you check the coils?

I would agree. If it is alway happening under a load or a certian RPM range it could be a misfire. It should though out codes though.

How do I check the coils?

Hope this helps on the coil pack issue. This does not happen to my car if I am in park. It's only when I am in drive and moving. Could it still be the coil packs? It is smooth while revving the engine in park.

In park you're not under load. It's strange that it's happening at the same rpm in different gears. If the clutchpacks in your tranny is going, it's almost never in all gears. I'd start checking other things first before switching your tranny.

Have you serviced your trans?

Mine was fine... and it started similar issues after servicing. Take to a place that do tips as they are very sensitive to poorly done servicing.

I have only had the car for one month. I don't know about the service. When I took it to the Porsche dealer for the PIWIS test, he did check the fluid level and it was okay. Do you still recommend the transmission service? How much do they usually cost?

Personally, I'd do it.
However, as the previous poster mentioned on cars that have higher mileage and have never had the trans serviced there's a small risk that the trans may react badly to the new fluid.
I have four other Mercedes with the same trans that are in the 02+ Porsches and have serviced them all. One was near 100k when I did it and no problems.
The trick is to use the correct fluid, change the filter,and I prefer to change only 4-5 qts of fluid, or whatever comes out of the drain plug rather than go with a full flush.

Hey guys, I'm new on here and was hoping for some info. I'm having the same trans issue's and was hoping someone has found a solution. I live in central Arkansas and we dont have a Porsche dealership here, so I've taken my '99 911 to 2 local "porsche" mechanics who "think" its torq converter problems but they dont know for sure. I dont want to spend that kind of $$$ to hope it will fix my issue. Any help??

I'm also new around here and have a 99 Tip also (which I just picked up). Mine has 86K miles and is due for it's first service at 90K (or at least I'm assuming it's first as I didn't get records). Is the surging you mention at a somewhat constant throttle? I haven't noticed anything like that at this point but am interested in everybody's findings.

Rich