Sparking when I try to ground the ignition coil harness. Cause?
 

I had some hot start troubles that ended up being a very leaky primary. I pulled everything, had the injectors serviced, and replaced them. While I had it all apart, I wanted to do a leak test on the injectors, when i turned the key to accessory so i could prime the fuel pump to test for leaks, the ground on my ignition coil mini-harness was smoking. Here's a pic of the wire in question.

http://www.bakemono-imports.com/rs25...oncoilwire.jpg

WHen I touch it to a ground with the key on, i get a spark. What should I check. I did not have some of the other grounds attached because the intake manifold was off. I was told by a friend that installing the other grounds might fix the problem. While I have the upper intake manifold off and everything is accessable, is there anything else I should check?

If you didn't have the other grounds connected, I could see that sparking. Everything else is trying to complete a circuit to the engine, connect that and there ya go.

The updated coil pack harness from Mazda doesn't have that ground strap, FYI. People have found that sometimes the original coil pack harness has problems with ignition breakup at high RPM, a new harness fixes that.

You may want to check your other engine grounds and make sure they're good. There's one at the bottom of the bracket behind the AC compressor (that's the main ground from the battery), one that clips to the firewall from the UIM, one that bolts to the top of the rear rotor housing from the engine harness, and one that goes around the rear UIM-LIM stud near the O2 sensor plug.

Dale

I'd definitely replace that harness with a new one..... it's from 1992 after all :)

@ Dale, does the new harness carry the grounds back through or ?

Beats me, it just doesn't have that extra ground strap. I'm sure there's a good reason it's gone :). They definitely work better than the originals, so there's definitely something Mazda is doing right.

Dale