Mother

Is the car actually pumping fuel during cranking?

jadduncan

It has a fuel pressure gauge showing good pressure (just replaced the pump after a dual pump at the track fix during the test and tune) I do not believe the injectors are firing, that is one of the DME error codes, but I have assumed it is related to a DME problem.

1999Porsche911

I assume you have checked the fuses, particularly for the fuel pump and dme? There is also an injector relay under the carpet behind the back driver's side seat.

Mother

Not sure of your kill switch setup and what it is killing, the battery, fuel, etc. That is why I was asking. Just curious what are you using to read these error codes?

jadduncan

Using the Porsche PS2 tester I think it is called. The work is being done by a shop that knows street Porsches very well. The issue seems to be related to the customization of the DME, or simply a bad DME, but we don't know how to test or even replace the DME as we don't understand how the street features can be bypassed.

The kill switch cuts off the battery completely shutting down all systems.

pat056

I had a problem with my kill switch in my 964. We looked at all normal things (DME relay, fuel pump, fuses...). We ended up just juggling the kill switch itself, turning it off and on. It finally cranked right up. I swore to replace that kill switch. That was 2 years ago. Switch is still in the car an it's never done it again.
Hope you get it solved soon. That car's too nice to not be on the track!

jadduncan

Good thought on the kill switch, but we have a quick connect for a second battery going directly to the engine/starter in case the small battery dies, and have hooked it into the system making the car crank very quickly, but still not want to start

The Porsche tester is showing that the DME is telling the car not to start, we just can't figure out why or more importantly what to do to make it start the car. I have a very good mechanic who has wasted a ton of time and effort and is very frustrated trying to get the DME corrected. If we knew how all the racing bypasses worked, we would be great, but I can't find anyone who understands the inner workings of the mystery black box.

I think I am going to send the DME to GMG Motorsports today to see if they can figure anything out

jadduncan

PS. Big thanks for all the help and suggestions. I was on this forum a lot about 10-15 years ago, but have moved to a local PCA forum. Nice to see so many helpful people out there lending a hand to a stranger!!!

Mother

FVD USA is tuning (via wifi connection) my custom setup SC and have cracked the Black Box Gnome I simply tell them what is installed (headers, gas etc) and how I am using the car they send me tuned DME maps to suit my needs. I think it would be nice even if you got your car to fire up that you still would not be in control not knowing how to tweak your engine for the future. Can't remember if you tried another stock DME to see if it fires up?

Anyway if you need FVD-USA maybe they have some suggestions.

FVD-USA
Mark Hatfield

Toll Free: 1-800-274-2220 ext. 27
Local: 1-954-977-7130 ext. 27
Fax: 1-954-977-7650

Lorenfb

"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."

Why then is the immobilizer still in the car if that function has been disabled
in the DME ECM?

"Can't remember if you tried another stock DME to see if it fires up?"

It's not that easy without all the coding info, i.e. one can't just plug in
another unit.

"I think I am going to send the DME to GMG Motorsports today to see if they can figure anything out"

Why would you do this without fully testing all inputs/outputs, e.g. all power
inputs (#30s & #15s), the engine speed sensor, and relay output drives?

jadduncan

I do not know how they defeated the immobilizer, but I guessed they jumpered something at the immobilizer, not internal to the DME, which is why it is in the car, but I do not know this for sure. It WAS on the list of things to remove for weight, but reliability issues have kept me busy in other areas.

I do not know how to fully test all inputs/outputs of a DME which is what I hope GMG can do for $250. We have read the PS2 fault codes and worked through the flow charts related to diagnosing those faults coming to the conclusion of a bad DME, but we doubt a new DME will work because of unknown solutions to the various alarm and airbag issues.

So we currently have a large, expensive paperweight and don't know how to move forward.

jadduncan

A stock DME should not work, but we have not tried it as the DME must be programmed to match the chassis and once you do that, it can't be reprogrammed for another car per my understanding. Thus it would be a very expensive experiment considering chances are very good it won't work. I did try the race DME in the targa as a long shot, and it appeared to recognize the car was wrong and would not even engage the starter.

Mother

Sounds like a good price and if they due tuning then works for the future. My airbags are out and still starts but have the idiot light and error code. Not to be a total pain but you may want to take a look at that immobilizer box and fuse. Frustrating I know but one thing for sure is in the big picture it will be working sooner or later and you will know allot more about your car....that's what keeps me going.

Todd Holyoak

The first step to figure this out is understanding how the immobilizer system works.

In brief, there is a small 'pill' in the ignition key that transmits a signal picked up by a transponder mounted to the ignition switch assembly. This device transmits a signal to the immobilizer, if the 'pill' is correct for the car, the immobilizer releases the starter relay etc and allows the motor to start. If not nothing happens when you turn the key to start. The DME and immobilizer are also matched. The immobilizer can only be programmed with a code once and this code must match the expected code in the dme. The immobilizer code in the dme can be changed to work with a differently coded immobilizer. If the immobilizer code in the immobilizer and dme don't match, again the starter relay is not released.

The fact that the car turns over suggests to me that this system isn't the problem and you should be looking elsewhere.

As stated, if the immobilizer functionality has been removed, there is no need for the 'black' box to remain, so I doubt it has been removed.

-Todd

jadduncan

Do you know how to remove the immobilizer from the loop? If we do that, couldn't we use any DME or would there still be other DME programming custom to the chassis?