993 Tiptronic dies, again

[drew 993]

Hi,

I have a 1997 993 S Tiptronic, everything original. I had the Tiptronic completely rebuilt two years ago, at 80K miles (all factory parts). I also had the micro-controller chip replaced. I won't go into the details but it was a long ordeal. The car worked great for two years and about 8 thousand miles, and then the forward running gears stopped with a sudden thud.

The shop ran diagnostics and error codes indicate that the tiptronic controlling computer is bad again. I find that hard to believe, unless of course there is some other electrical problem with the car that would cause the chip to go bad (electrical problem somewhere causing high voltage or high current or short that would impact life of the chip). These chips should last a very long time, the first one lasted over 10 years (it should have lasted 100).

If anybody has experience with this type of problem I would appreciate any insight you have. These chips are now about $2500.00 (up from $1,600.00 a couple years ago); I understand there are only about 40 left at the porsche factory.

thanks,
Andrew

P.S. I love the car and am the second owner, got it with 40,000 miles on it. I have owned it for seven years and plan to keep it forever. Its the best driving machine I have ever been in. However, in my experience the reliability of the car is very different from what I have read online and in the literature. I maintain this car mechanically very well. However, this car breaks down all the time. The list of mechanical issues that have arisen is incredibly long and started at about 50,000 miles. The most significant was the complete engine rebuild, then the transmission, wheel cracked, tach, on and on and on it goes. I drive it hard and fast at the track, just like it was born to be driven. Still, nowhere close to the reliability/robustness I was expecting. The driving experience though is beyond what I could have imagined.

[Joe Bob]

Is it a chip that can be read and copied? Like the DME chips?

If it is...Steve Wong or Ingo Schmitz can probably help.

Have you tried to sorce a chip at Parts Heaven or any of the other bone yards?

[geolab]

Hi Andrew, I am sorry for your experience. I could not but answer your questions without fealing revolted, so if I sound angry, it is not against you....

First to start, your tiptronic was rebuilt two years ago with 80 k miles with factory parts.
There is no factory parts for the tiptronic, there was a factory policy since 2004 and a TSB issued back then that no tiptronic parts would be available, and the box should be changed as a whole. Less when there were parts for the tiptronic before 2004, it was only a few sprockets and oil seals only.

You had the micro-controller chip replaced.
There is no microchip to replace. There is a module (brain) under the passenger seat that contains an EPROM. This EPROM can be flashed only once. Why?
because RestOftheWorld cars have a different program mapping than the US models. And if a european car was exported to the US, the dealer could reflash the EPROM to the US mapping. This could be done by the factory computer called PST2, porsche system tester 2.
now some aftermarket diagnostic readers can access the cars brain, and if a stupid mechanic reflashes the tiptronic brain thinking he can reset it, he will kill the brain.
These tiptronic brains are unbreakable, undestructable, unless you mingle electronically with them through an OBD reader. No electrical problem could harm the Tiptronic brain.

I bet the mechanics only removed the tiptronic, and changed the forward clutch seal. That is a known issue in these transmissions.
What breaks this seal is the fact that when car is warm, you put the gear knob in Park and you rev the engine. The excess pressure burns the seal. This happens a lot in emission control tests.
To avoid that, when box is warm, you should turn off the engine for thirty seconds to depressurize gearbox, and then run engine and rev only in Park position. If you select any gear, the gearbox will be pressurized again.

Alert tiptronic problem failure very serious please distribute

As for engine rebuilt, if it was running, you shouldn't have touched it. But scrupulous mechanics advise you the contrary...

As for robustness, I honestly had an experience with this. Had an emergency back in 2005, and needed to travel to the middle east immediately with no tickets available for the following days. I grabbed a small back pack and a huge bottle of soda, and took the 993. I drove 34 hours continuously and crossed 10 countries. 4205 kilometers from constant 250 kmh on german autobahn through two feet mud roads in Serbia Croatia and Bulgaria etc.
On my arrival, I only washed the car.
In fact it was so reliable, I redid the trip the next year willingly

Now for solutions, please note that tiptronic rebuilt boxes from ZF (original builder of the 993 transmission) were $3000 last year. That's good to know as assurance.
where are you located US or Europe, ? regards