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2001 Boxster Tiptronic -when taking off in 2ND it tries to shift but doesn't. What is problem?

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Thank you for advice on motor mount. Replacing it solved clunk sound, so on to shifting problem.

When starting in 2ND gear in auto mode it feels like the transmission is going to shift but doesn't, it just jerks then pulls some more before changing to third. The harder the start the harder the jerk before accelerating, and changing to 3RD gear. In manual mode, it doesn't to do it, unless I'm starting slowly and I feel a hint of the shift attempt. Local Porsche dealer installed new transmission control module after which in now starts in 1ST gear when engine is first turned on and then after stopping in always starts in 2ND. Dealer said this was due to new programing and said no codes were showing up. This problem has been around for a couple of years, but is getting more pronounced.

Last year a performance shop serviced transmission and afterwards it would jerk when giving gas immediately after stopping, so added half of liter of Porsche fluid after heating the transmission to 86 degrees F. This improved shifting although recently felt jerk when breaking hard then quickly hitting gas at intersection. Would it be worth doing another transmission service (myself) and replacing fluid with Pentosin. Does it matter if I have a mix of fluid, since I've read the torque converter will not empty when draining transmission fluid. If replacing the transmission is close at hand, I don't want to spend $300 on service parts on bad transmission.
a comment
por911(bc) - Sunday, 22 July, 2012, at 7:56:36 pm
Yes, a second change out of the fluid will probably help. The tip gearbox's, like many euro/zf auto trans units like really clean fluid to operate smoothly. You might consider changing out the fuel filter, if it has not been done in a while. One element that really smoothed our 01 base out , was replacing the trans mounts. They were collapsed after 45k.
regards
Quote
Krbintn
Thank you for advice on motor mount. Replacing it solved clunk sound, so on to shifting problem.

When starting in 2ND gear in auto mode it feels like the transmission is going to shift but doesn't, it just jerks then pulls some more before changing to third. The harder the start the harder the jerk before accelerating, and changing to 3RD gear. In manual mode, it doesn't to do it, unless I'm starting slowly and I feel a hint of the shift attempt. Local Porsche dealer installed new transmission control module after which in now starts in 1ST gear when engine is first turned on and then after stopping in always starts in 2ND. Dealer said this was due to new programing and said no codes were showing up. This problem has been around for a couple of years, but is getting more pronounced.

Last year a performance shop serviced transmission and afterwards it would jerk when giving gas immediately after stopping, so added half of liter of Porsche fluid after heating the transmission to 86 degrees F. This improved shifting although recently felt jerk when breaking hard then quickly hitting gas at intersection. Would it be worth doing another transmission service (myself) and replacing fluid with Pentosin. Does it matter if I have a mix of fluid, since I've read the torque converter will not empty when draining transmission fluid. If replacing the transmission is close at hand, I don't want to spend $300 on service parts on bad transmission.

Generally if the Tip fluid is left in too long it is better to just leave it alone. The problem is after too long it appears -- what I'm told by those that come in contact with a lot of Tips -- is the fluid change seems to accelerate the Tip's demise.

It is probably not long for this world in any case, but the fluid change hastens its exit.

So the advice is to change the Tip fluid (and filter) *before* any symptoms appear and to change the fluid at least when it is due to be changed or don't change it at all.

Now in your car's case the Tip is already exhibiting some symptoms.

You may be throwing good money after bad but a Tip fluid/filter service -- using the recommended Tip fluid -- may (though of course I can offer no guarantee but have all my fingers crossed) -- may make things better.

Porsche doesn't recognize but one or two fluids as suitable for use in its Tip. If one stays with the recommended Tip fluids they are miscible. There's no reason to flush the old fluid before adding the fresh fluid.

Remember a Tip fluid change does not include the considerable amount of fluid that is retained by the converter. Thus a Tip fluid flush would require draining the converter -- if this is possible -- and of course refilling it.

Or worse case is changing the fluid then using the Tip for a few minutes, then draining this mixture of old and new fluids and refilling with the new fluid and possibly doing this again to bring the level of the oil fluid left in the new fluid down to I can only guess what would be a 'safe' level.

Porsche offers no guidelines, as far as I know, on what it takes to prepare a Tip for a fluid not on its approved list so the above is just a WAG on my part.

Sincerely,

MarcW.
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