I have a Koni Challenge 996 racecar that just got a new engine, ran great during break-in and now simply will not start. It turns over, but the DME seems to be telling the car not to start (lots of reasons, unbelievable flywheel sensor, bad injectors, etc, etc), all of those components are new and test good, so I believe it is the DME.

As I bought the car from RPM Motorsports who raced it, but have since gone out of business, I don't know how to change the DME as it has to be customized to allow the car to run without airbags, alarm, etc. Does anyone out there with more experience with 996 electronics have ANY suggestions.

We are really at a loss here....

THANKS.

 

The 996 used 3 different DME's.
DME 5.2.2, DME 7.2, or DME 7.8 - which do you have? or did they use a GT3 racing Motronic?

 

I would check for the obvious, the plug going into the DME and all the surrounding grounds. Grounds can drive you in circles, with all the things that it is saying is wrong.

 

Disconnect battery for 10 min and reconnect. Check fuses and DME relay at back if your car is similar to component locations as stock 996.

 

Not sure how to tell which version it is, but it has the same serial number 996.618.604.00 as my 03 Targa, and was/is running a normal (non-GT3) 3.6 engine. It has been in and out numerous times for checking and the power is killed via the kill switch whenever the car is off for any length of time. All fuses are good, car cranks, but will not fire with the DME codes implying the DME does not want it to start for a host of reasons.

 

Way outta my league here, but did you try the DME from your Targa in this car, or visa versa to see if you got the same error messages?

 

DME's are a one time programming per car serial number per my understanding. The Targas will not work in the racecar as the airbags and alarm are missing and thus would not start. As a long shot, I did put the race DME in the Targa, but as expected, it wouldn't even turn over as it recognized the car, or alarm or something was wrong. (The racecar turns over, but won't start).

Thanks, keep the ideas coming....

 

Have you reseated connectors X59/1 and /2 (round connectors in the engine compartment, sort of under the right rear quarter panel) as well as all the connectors on the DME?

 

Can you explain this alittle better.

 

We have removed most of the wiring harness trying to find any shorts or frayed wire and when the car is left overnight, the power is off at the kill switch to save the small racing battery. It was working fine until I went to start the car to load onto the trailer after a test and tune day with the new crate engine. The power was never cut between when it worked fine and when it decided not to start, just sat in the pits for an hour or so.

 

These would all have been removed and reinstalled while testing and looking for shorts.

 

Is the alarm system (black box under seat) in or out of the car? If in it has a fuse a external fuse.

 

I'm not sure if the DME is like most of these units in other german cars, but if so you may need to actually clear the internal fault codes using a device which can directly access the eeprom or static memory in that specific module (assuming PST2, paging Loren?).

I've had to do this on AMG before, even though the wiring fault detected was corrected it wouldn't restart until specific subsystem modules were cleared on a real SPS.


That may be way off, but if you are losing practice/about to miss an event or something, is there a reason not to go from the motronic to another 3rd party unit?

 

The car still has the black box, but it has been defeated in some unknown way when the car was original converted to a race car. The DME is not giving an alarm system error, so I don't think that is the problem.

Does anyone know specifically how these systems are bypassed for a racecar? Ironically, we ended up buying this car instead of building a similar car from scratch in order to avoid this DME mess

 

The fault codes have ALL painfully been checked and cleared on the official Porsche fault reader without any success after many hours of following flow charts, but new and different faults just appear.