2001 3.2S Tiptronic - Gearbox "slipping"?
2001 3.2S Tiptronic - Gearbox "slipping"?
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Discussion

MG Mark

Original Poster:

618 posts

244 months

Thursday 1st September 2011
quotequote all
The characteristics of the gear change on my 2001 Boxster 3.2S Tiptronic seems to have changed subtly when driving it in manual mode, from its usual crisp changes.

Symptom is that the gears shift fine with no abnormal warning lights etc but, particularly when accelerating relatively gently in normal driving conditions, or driving up an incline, the revs rise by about 400rpm without any actual acceleration, before decaying back to what they were at and then rising as actual acceleration of the car happens. The down shifts don't seem to have as much engine braking effect as they normally would. Sort of feel like the lock up in each gear is not engaging as quickly it should - it might not be that which is the fault, but that is what it feels like - any thoughts??

MG Mark

911p

2,361 posts

206 months

Thursday 1st September 2011
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My Dads last C4 tiptronic did this for the 2 years he had it, seemed perfectly normal. I wouldn't worry about it.

Pope

2,653 posts

273 months

Thursday 1st September 2011
quotequote all
Disconnect the battery as a test - this will reset any transmission adaption values. The tiptronic ECU can adapt to a particular driving style which sometimes gives the symptoms described. Any recurrent fault stored will return for diagnosis with a PIWIS tester.

What's the service history like? Mileage? Any leaks? The transmission doesn't need major maintenance officially until 96k miles but the fluid level should be checked annually (low fluid level will give 'slippage' symptoms)

browno

526 posts

260 months

Friday 2nd September 2011
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Sounds to me like you might benefit from a fluid change - sounds like the friction of the clutches has dropped a bit, and the clutches are slipping slightly on the shifts. I think that getting some clean ATF in there should improve things...

Sunnysidebb

1,385 posts

193 months

Friday 2nd September 2011
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Hi,
Why don't you give: http://www.nineexcellence.com/ (there based near London)a call. I have just had my tip modded by MKB. Kens sends them out to Germany to have them done.
if you give them a call and explain your problem he might be able to talk you through the problems.
However, firstly I would have your tip fluid level checked. The workshop says the fluid should changed at and at 98k. But it wouldn't do any harm to have the fluid changed along with the filter after 50k. The tip atf can break down very very quickly if it gets too hot, as quickly as only 2k in severe cases.
Naff fluid and especially low level or blocked filter can cause your problems.
The other reason for your type of fault is a worn clutch pack, but this is normally on 3rd to 4th gear change. The other reason is a defective pump, cracked pump housing reducing the clamping pressure of all the clutch plates, causing slippage in all gears and also lock up problems coming down the gears.

ps this is for the 996tt tip, so maybe the intervals are different for your car but the principal is the same.
Frank



Edited by Sunnysidebb on Friday 2nd September 08:53


Edited by Sunnysidebb on Friday 2nd September 08:53

911p

2,361 posts

206 months

Friday 2nd September 2011
quotequote all
It might be worth adding that my Dad has the tranny fluid changed at about 65k miles, it did make the shifts much smoother. Definitely worth doing.

tracydeedance

787 posts

205 months

Friday 2nd September 2011
quotequote all
Hi
our 2.5 tip devoloped rough changes and slipping and changing up and down the box at will.We never had any lights show up. Changed the fluid in the box no change.
After a mechanic said have you tried a change Of MAF which sounded weird to me
but we did and after half an hours driving perfect.
Try to swap with someone and drive for half an hour to see if there is any difference.
Might be something different but worth a try.


996ttalot

1,931 posts

201 months

Friday 2nd September 2011
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If I have understood you are saying that the revs slip 400rpm and then come back to where they started? e.g. at 3000rpm , goes to 3400 and then back to 3000?

You need to get the car checked with a PIWIS.

It might not be the gearbox since 400rpm slippage does not drop the revs back and is normally associated with brisk driving.

Changing ATF will do nothing. In fact it can actually cause more issues because it can disturb debris build up into somewhere you don't want. The only time we change ATF is if we are opening the box up.

Slippage is caused usual by either a leaky piston within the box or clutch pack wear. Either of those can now be fixed at good prices so that you are not writing the car off.

Best advice is to get the PIWIS to see what codes are present. If none, then you need to get a print out of the adaption values for the tiptronic control unit. DO not disconnect the battery because you will then lose valuable data to analysis.

If you need to speak give me a call on Monday.

Ken @ Nineexcellence.

Sunnysidebb

1,385 posts

193 months

Friday 2nd September 2011
quotequote all
Ken is correct to a certain point about changing the ATF. BUT, one thing to note is that heat has a significant effect on the life of ATF,see the chart found on the link. It highlights the drastic effect of heat on ATF:

http://www.transmissioncenter.net/TransTemp.htm

So if you change your fluid, drop the sump plate and clean out thoroughly and change the filter as well. Any other debris is already in the internals of the TIP so theres nothing can be done about that.

ps....
Hows my car coming on Ken. I cant wait.lol

MG Mark

Original Poster:

618 posts

244 months

Friday 2nd September 2011
quotequote all
Thanks for the thoughts all, useful food for thought.

Ken - your interpretation of what I wrote is absolutely right - the revs rise by about 400rpm, with no perceptible acceleration, then the revs drop back and the drive starts to be felt. Happens in both manual and drive modes; in drive it feels like having a gentle 2-stage kickdown (without operating the kickdown!). Decelerating feels like the engine braking is much reduced. Will give you a call on Monday

Mark