SimonWoodall

91 C4 Coupe
If I turn the key, the engine fires, and will continue to run so long as the starter is running. Release the key and it dies.
I wondered about the ignition switch, and stuck my head under the dash to see how to remove it. I can unscrew the lower screw, but how the h*ll do you get at the upper one which is tight against the metalwork?
And is that the right answer?

onceover

Could be the DME relay

SimonWoodall

I thought that, but I keep a spare genuine Porsche DME relay, and swapping them does not make any difference.

onceover

Was worth a shot!

I would try to do some more investigation before removing the lock cylinder, I don't think thats the problem.

Do all the lights turn on and everything work properly aside from the engine running when the key is in the ON position? If so I doubt its the ignition.

The DME runs the fuel pump when the key is in the starter position, once it turns to the ON position there should be a engine speed signal to the DME to let it know that its running. I have a feeling there is something up with the DME not getting a signal telling it the engine is running and thus it cuts the fuel pump.

newsboy

If the engine runs, your getting spark and gas, so it's probably not the flywheel speed sensor, But it's worth a check. To test this, you open the DME relay(under drivers seat) and used a multimeter set to AC voltage, across pins 47 & 48 of the large plug. iT's supposed to read 3 volts.

SimonWoodall

Ok, I did have a DME relay problem, both my relays had faults, a different one in each, so they're both in the bin. But whilst checking this out, I found that with the ignition on, if I wiggle the key, I can kill ALL the lights on the dash, which leads me back to my original premise of a problem with the ignition switch, so how the heck do I get this out?

Gordon52

I had to replace mine on my 89 back a couple of years ago, as I recall it was NOT fun as there is no front access for the switch removal.Two screws from behind the dash, bottom one not so bad the top one was difficult , just no room. I had to remove a "box" near it for what access I could get.
I used a small socket type wrench that I could slip a phillips bit in from my drill which made a nice right angle tool with just enough room to work.....I had to do this blind as there was no way to see as I was working but in the end I won! Once the two screws are out it is a pretty straight forward replacement.
Hope this helps ...
The other option that a shop wanted to do was remove the dash $$