Thought the coil was bad (no apparent spark), so replaced it. Car started after some cranking. The car is not starting consistently. Measured the voltage to the coil while turning over the engine, and had 0.5 vdc. I assume there is 12 vdc to the coil when the car does start, otherwise there would not be sufficient voltage to create spark at the plugs.

What else is in this circuit which could be affecting the 12 vdc at the coil?

 

Sounds like the CDI box may be taking a crap.

 

PorscheDoc,

On this vehicle, how & where does the CDI establish ground to the body?

 

IIRC, all the grounds to the CDI and wiring harness should be at the coil mount. The only other ground on the motor is the alternator ground which is behind the engine fan on top of the case.

 

PorscheDoc,

Believe I found the problem, as the plug side of the CDI had been tampered with. The female disconnect connector for terminals 3 & 7 had been replaced with a non-Porsche version, neither of which have the little tab to keep them firmly seated within the plastic plug. As a result, they had both worked loose.

Reseated/reassembled everything, and the engine started immediately. I would now like to replace the two female disconnect connectors with the correct ones, which will hold captive when inserted into the plastic plug.

Could you provide the Porsche P/N for this item?

 

Hmmm good question. I went through PET looking for a part number for those connectors and did not see anything in the electrical section separate from the wiring harness. I did find connectors in the 944 section, but I can't verify that any of them are the correct size. It may take finding a junkyard 930 and cutting the plug off the harness and soldering it to your harness.