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Fuel pressure regulator is what I'd check after DME, but the crank position sensor is another thing that can start to fail in odd ways, and its cheap to replace.
I will order a crank sensor to fit myself, won’t do any harm. Easy fit?
it got a brand new fuel pressure regulator in 2019 so I doubt that’s the issue, however I will clean the ISV in the meantime for good practice.
Seems odd if you jump the relay everything works but if you don’t it doesn’t. Is this one of the solid state relays with or without pump prime? Might be worth hooking up a pressure gauge to the fuel rail and see what’s going on. When was the last time the injectors were inspected/clean?
Crank sensor could also make sense since ECU won’t turn the pump on until the engine is cranking.
Seems odd if you jump the relay everything works but if you don’t it doesn’t. Is this one of the solid state relays with or without pump prime? Might be worth hooking up a pressure gauge to the fuel rail and see what’s going on. When was the last time the injectors were inspected/clean?
Crank sensor could also make sense since ECU won’t turn the pump on until the engine is cranking.
My current DMEs aren’t pump prime
in 2019 was the last inspection car has been doing very little driving maybe, at most, 300 in 4 years. I do a 5/10 mile drive in it once a month keep everything happy.
My car had a broken solder joint in the alarm module that would randomly shut off the DME relay. If jumping the relay manually fixes the issue and you can absolutely rule out the relay itself then you must dig into the wiring diagrams and find/test/jump every possible circuit that is involved in the power to the relay. I finally found the alarm circuit and jumped that circuit at the alarm connector. Re-soldered the PCB and was good to go.
pete
Great point. I keep forgetting the alarm module but you are right, I have had an issue with it a long time ago. Same thing, broken solder. These cars are now over 30 years old and some components start to age out, even with relatively low miles/kilometers. I just resoldered my CCU PCB after losing power to the fans.
The F 9 technologies pump prime solid state DME arrived yesterday and did not work.
I plugged it in and the lights flashed instantaneously fora split second and then off again and they did not stay on for three seconds and prime the car like they were supposed to. However when I went to start the car they did turn on while starting and the car started.
Today when I went to check again the DMEs lights will not turn on even when turning the engine trying to start... video attached anyone have any ideas?
Faulty new DME? Faulty wire from ignition to DME? I don't know.
I second the alarm and its immobilizer, i might be wrong but the same symptoms i had with my 1st Carrera 2, my auto electrician disconnected it no more random problems as you have described.
I would start checking all the wiring in the car including all the ground wires from the battery, transmission etc. I’ve also heard that the ground wire on the battery can deteriorate to a point where it starts causing starting issues. Porsche released an updated ground wire that has a shield to minimize deterioration.
I'm surprised a qualified air cooled mechanic can't figure it out, when things like that occur its such a pain. Keep us updated, will be interesting to find out the solution when you figure it out.
I had a similar issuie - relay (R33) Terminal X - Feeds +15. Mine was correded inside causing voltage drop. - solved my intermentant issuies that are close to what you describe.
I had a similar issuie - relay (R33) Terminal X - Feeds +15. Mine was correded inside causing voltage drop. - solved my intermentant issuies that are close to what you describe.
That's worth a try.
My update so far,
There is only 8/9 VOLTS going to the DME when the ignition is in on position. I tried creating a new earth by connecting an additional wire from pin 85 (ground) to a suspension arm purely for test purposes to see if an immobiliser was still drawing voltage. This had no affect, so I believe it may be as your say, R33 or a full in wire between ignition and DME. Can't drive the car anywhere for the past while as I have to hop out of car to start it.
I had a similar issuie - relay (R33) Terminal X - Feeds +15. Mine was correded inside causing voltage drop. - solved my intermentant issuies that are close to what you describe.
How do I check this relay and how would I buy it, is it on deign911.
I have 8/9 volts when ignition on and when starting asset
Anyone have any other ideas as to why there is only 8/9 volts traveling to DME. Anyone know a way to run new wire from ignition to DME to give the DME the correct voltages while not losing out on all the other ignition circuit needs.
07-29-2023, 09:16 AM
