924S Coil testing - newb

[JoeKL]

My '87 924S wouldn't start in a parking lot after a short drive the other day, then randomly started 2 out of 5 times since. Now its dead.

I changed the fuel filter and fuel rail damper because it has 70k miles and I didn't know when they were last done, also am planning on installing full tune up parts. All systems were checked and there is no spark, and fuel pressure in the rail is in spec.

The coil will also be replaced based on mileage and in car test w/ignition on and manual momentary grounding of the - side w/a spark plug. It was non functional.

However I wanted to know if my test results for the old coil made sense to anyone who could help me understand.

I conductivity tested both the primary and secondary coils w/ohm meter and they were both in spec. I also checked for shorts between coils, coils and body, and it was ok.

Then I bench tested the coil with a spare battery spark plug and various wires, all tested, by momentary grounding of the the (-) side of the coil with a test plug in the primary circuit. NO SPARK.

Any insights into why the coil will not functionally spark when it seems electronically sound via testing would be interesting and enlightening.

Thanks in advance.
JoeKL

[JoeKL]

Nothing ?

Hmmm, a little help would be .... very helpful.

I put in the new coil, wires, cap and rotor and still no spark. I have power to the + side of the coil in the car but can't get the new one to spark a plug with a manual test either. I figure I"m doing something wrong but can't figure out what.

Again, thanks in advance.
JoeKL

[Gawernator]

Don't know what to say about that, however if you still have the original coil, now more than 25 years old, you should probably buy a new one anyways. Somehow mine is still working!

[JoeKL]

Thanks for trying and for the good advice.

I replaced the coil, plugs, plug wires, cap, & rotor...

STILL NO SPARK.......

Any suggestions would be very much appreciated. Does the spark signal come directly from the ECU? Where is that located on an '87 924 and is it testable?

Joe

[Rasta Monsta]

Next steps:

1. New DME relay.
2. New ignition switch.
3. Check wiring to speed and reference sensors for cracked or corroded connectors.

[JoeKL]

Thanks again for the help. I rechecked all of the above and it turned out to be the reference sensor connector. The first time I inspected them, I did not do an adequate job. This time, I disconnected them at the bracket and the inner plastic just came apart on the upper sensor connector.