Tiptronic Help/Advice
 

He guys, my tiptronic started not going into 5th from 4th in auto mode. In tip mode, I could shift through all the gears just fine. Took it to my Porsche mechanic & hooked it up to the pst (sp?) tool & it had solenoid fault codes. Changed the fluid, but no change. I bought a used tip & installed it. Shifted fine for about 30 miles. The next morning it was back to being the same as before. Bought a torque converter, installed it, no change. Mechanic said the fluid is perfectly full and the car is not throwing any codes. He thinks i bought a bad transmission. Oh...the used tranny & TC are out of the exact same year box as mine. I'm at a loss. I don't think it's the TCM either, but I don't know at this point. Any help would be very much appreciated.

I have a Tip and this question will seem like a simple one but...does the trans have a computer that controls it? With all that's been changed, and it's still doing the same thing, it could be in the shifter, wiring or the computer.

It does have a transmission computer (TCM). The reason I don't think that is the problem is because it shifts through all the gears just fine when I put it into "manual" or "tip" mode. So, that would suggest (to me) that the computer is working to change the gears and I'm back to I guess not having enough pressure inside the tranny to shift into that 5th gear (which requires the most pressure & hence that one failing). Again, these are all guesses from me, as I really know little about transmissions.

Bad shifter switch.

BTW, whoever counselled you to swap the tranny as a first course doesn't know squat about these boxes - get another mechanic.

Cheers!

This would be such a relief!

Is this what mounts to the side of the transmission the linkage attaches to? If so...the new(used) transmission that was installed already had a different one on it. So, the old one(switch) was removed with the old transmission and not reused.

I thought I read about this switch causing the car to not be able to shift in manual mode rather than automatic mode?? My trouble is automatic mode from 4th to 5th. Still the same culprit...the shifter switch?

*subscribed in case I ever run into this*

I have no experience with the Tiptronic tranny but could linkage adjustment be an issue?

I would not think it was the TIP but another problem. One being the TCM, the switch on the side of the TIP or a blockage in the cooler line going to the front and back. Electrically it could be the harness. Like Lil Bastard, I would seek out a top TIP expert first. Good luck. :cheers:

The guy I went to has a PST2. So, i'm assuming he tested everything electronic. Coolant has been flushed. Transmission fluid and filter are brand new. The transmission, torque converter and transmission switch have all been swapped out w/used units. What's left? TCM & harness? Wouldn't problems w/those have been caught w/PST2? Btw...This guy I go to is supposed to be top of the line here in northeast FL for Porsches.

I'm not an expert on your problem but I've been thinking about it and have one possible answer. Porsches and many other cars have a warm up mode that tries to make the engine warm up faster to reduce emissions. In other brands of cars this mode locks out high gear but I don't know if Porsche does it that way. This theory would account for shifting in all gears but high. Maybe it could be triggered by a failure of a engine temperature sensor. I had a Chrysler Sebring that would lock out high gear in very cold conditions until the motor warmed up.

I found an item in a Porsche technical document that discusses it.....

Warm-up Map
Apart from the 5 shift characteristics, the control unit also
has a warm-up map which becomes active at engine
temperatures < 90° F. (32° C.). In the warm-up map, the
shift-up points are offset to higher engine speeds, the
transmission starts in 1st gear, and the convertor lockup
clutch is opened. These measures result in both the
engine and catalytic convertor rapidly reaching operating
temperature.

Another place in the same document talks about the factors that go into determining when the car will shift gears. A number of sensors are used but I don't see how a problem with them would apply to high gear only.

Driving In Selector-lever Position “D”
If the selector lever is moved to “D”, an extremely
intelligent driving program is performed.
Shift characteristics adaptation is carried out on the basis
of the following information:
l Accelerator pedal position - Throttle potentiometer
l Vehicle speed - ABS sensors
l Longitudinal vehicle accel. - ABS sensors
l Transversal vehicle accel. - ABS sensors
l Engine speed - Speed sensor/flywheel

Also as I read the document it looks like the transmission controller, which seems to be a separate computer unit that manages the transmission, could have a fault that would generate similar inappropriate actions in the old and replacement transmissions. The control unit sends signals about how to operate the solenoid valves and system pressures. Again, this is just a guess on my part. Maybe a replacement transmission controller would fix it.

This did not correct the problem. Could it be the TCM, or harness even though it did not show any faults on the PST2?