928 at last

At least they were able to expand their skills to new heights with the obvious challenges presented.

gcthree

My '89 S4 is fitted with a limited slip differential. Reading the Ott/Veninger document on flushing, they reference that it is not used on LSD's prior to 1990. Just confirming that this correct?

Bertrand Daoust

This is correct.
Porsche introduced the PSD in the 928 in 1990.

Bilal928S4

They have actually been very hard at work on the new Porsche. They have perfected their craft on the new 911. You have to remove the entire rear bumper assembly to even check / replace the air filter.

worf928

Standard equipment in 1990. Optional (in Europe only?) in '89. Dash wiring in '89s is 'ready' for PSD.

Vilhuer

No, RDK was option in ROW markets and even standard in '89 GT's for some markets but PSD wasn't.

worf928

So you are saying that PSD was NOT an option in '89?

The wiring diagrams for '89 show the wiring for PSD (M221). I have direct first-hand experience that the dash harness, abs harness, and instrument cluster firmware are "PSD ready." I assumed that since there was wiring and an option code that it was an option.

Vilhuer

Yes. I can be wrong but AFAIK no one has seen PSD in '89 MY car but PET lists 11 cars with option code M221.

WP0JB0928KS860061
WP0ZZZ92ZKS840061
WP0ZZZ92ZKS840062
WP0ZZZ92ZKS840063
WP0ZZZ92ZKS840064
WP0ZZZ92ZKS840065
WP0ZZZ92ZKS840066
WP0ZZZ92ZKS840067
WP0ZZZ92ZKS840068
WP0ZZZ92ZKS840069
WP0ZZZ92ZKS840071

So it looks like factory did just one US model and 10 German cars with it. All are very early cars which means they were likely factory demonstrators or one could even call them prototypes for '89 MY production. For some reason Porsche decided to leave PSD out for a year. Maybe they thought it wasn't ready yet.

Same thing was done with ABS option on '82 MY. Four ROW cars have M593 option listed and they are earliest two 4.5L and 4.7L made.

WP0ZZZ92ZCS800051
WP0ZZZ92ZCS800052
WP0ZZZ92ZCS840051
WP0ZZZ92ZCS840052

ABS made comeback two years later on 4.7L ROW models.

Tails

Dave,
I can confirm that the PSD was designed into the 1989 Digital Instrument Cluster, as was the air bags and as we know some 1989 manufactured cars were actually built as 1990 models. This Instrument cluster was a K25 model and was manufactured in Dec 1989.

When I was chasing a fault in my 1990, I installed a loan 1989 digital instrument cluster manufactured in July 98 into my car and the PSD was operational, as it was also a K25 model. I have now fitted a later K29 model in with original set up in the German language, which I believe was the latest model and all functions on my 1990 are still fully operational, however I believe that the Diagnostics for the Instrument Cluster has been change some what to the original. I still have to check this out. I have changed the language to English, but the Stop Light indication is in German, but no problems. now need to reset the odometer to the correct kilometres and trace the fault in my old #2 PCB, if possible.

worf928

To OP: