996 Tiptronic Cornerns

[berrytastic]

Good day to you 996 owners.

I own a 1999(T) 996 C2 Tiptronic, and have noticed that the gearchanging seems a little odd now after using the kickdown yesterday, and would like some advice on whether it is a problem.

This happens randomly at various speeds, and the car is not being driven hard. I noticed that when the car changes gear (in D mode not M mode) that the revs increase during the change (i.e 2000 up to 2400 then down to 1600). Almost as if the throttle is staying open when the change occurs. The car changes gear through the range and in M it seems fine. And when I take my foot off the throttle the revs on some occasions drop to 1600 irrespective of what speed I am travelling (i.e at 70mpm @ 2000 rpm, the take foot of throttle it will drop to 1600rpm even if the car is rolling at near 70mph).

The engine is running fine and has no loss in power or fluctuations.

Plus it seems to have developed 1/2 gears too. It will be in 5th and when I apply a little more throttle, it seems to change down 1/2 a gear, but still indicating 5th.

Any thoughts, suggestions or advise is most welcome, as my heart started to sink when I started to notice this, I put all I owned into the car and I love it, and fear it could be big bill.

Regards

 

[Richard_Hamilton]

Stuart!!

I don't know how many miles the car has done, but I would suggest getting the ATF and filter changed. It is supposed to be done at 96,000, but that's way too long IMO. Popular opinion on the American sites is that it should be done at about 50,000.

 

[berrytastic]

The car has 93000 on the gearbox, and 44000 on the engine.

 

[minny]

Get the ATF and filter changed. Make sure you use the proper Esso LT 71141 fluid that is the only recommended fluid for this ZF box. The sump gasket could be leaking slightly and the wrong fluid level or old fluid could be causing the symptoms.

Even on the ZF website they now advise the fluid change sooner to improve "comfort of gear changes". I guess they don't want to shoot themselves in the foot by saying it would prolong the life of the box and admit the original fuild change interval was too long.

 

[CLIFFWILKINS]

Hi
We had exactly the same symptoms as yourself on a Boxster Tip.
Good advice to get the fluid and ATF filter changed which made changes feel better.
Still had over reving between gears and a half a gear like yourself.in our case.
Many could not dignose the problem, not until Ispoke to Charles Marsland
who had come across this before and said before a gearbox change etc,
try the air mass (Maf) change first. Hey presto smooth changes and no half gear anymore.
May be worth trying .
Cliff.

 

[CLIFFWILKINS]

PS.
Forgot to say changing MAF was not a complete instant fix
as your have to drive it for a few miles first for the brain thingy to
sort its self out.
But after few miles perfect again.just gets better with miles.
in our case anyway. Hope this will be a fix for yourself.
Something to consider.

 

[minny]

ORIGINAL: CLIFFWILKINS

Hi
We had exactly the same symptoms as yourself on a Boxster Tip.
Good advice to get the fluid and ATF filter changed which made changes feel better.
Still had over reving between gears and a half a gear like yourself.in our case.
Many could not dignose the problem, not until Ispoke to Charles Marsland
who had come across this before and said before a gearbox change etc,
try the air mass (Maf) change first. Hey presto smooth changes and no half gear anymore.
May be worth trying .
Cliff.

Just to add that the gear changes on my own Tiptronic box was still slightly jerky after 2 fluid changes ( each change only drains about half of the total fluid) so I changed my airmass meter and it helped. At the time there was no engine fault light but after 75k miles, I figured the air mass meter was past its best anyway. If you do decide to change it, disconnect the battery after for 30 minutes or so so that the engine can reset the fuel trim and learn the new parameters.