eliasmazur

Hi,

One of my coils was very corroded so I ordered a pair of used coils from 928intl.com and replaced them today. I noticed though that the coil I received had a black body as opposed to the ones on the car that were bare metal. I know the coil needs to be ground through the bracket, but the ones I got feels like it has a plastic cover or coating and it's definitely not bare metal. After installing I tested with a multimeter and of course it's not connecting to the ground.

Part number is exactly the same as the ones in the car from Bosch. Yes, I did replace the cables as well.

I don't want to start the car up without knowing for sure that this is not an issue. Any help?

Thanks.
Elias

PS - Forgot to mention that mine is a 86.5

dr bob

The coil itself does not need a ground through the bracket. The coil bracket ground wire to the engine, if you have one, is for ignition noise suppression, and can provide an additional direct path to chassis ground in case the main engine-to-frame lead is damaged or inadequate. Bottom line: You are fine with the coil paint/coating intact as it is.

eliasmazur

Thanks for the quick reply. Interesting, I was just checking the 928intl.com again and the coils I got look like the one they have listed as being from 89 - 95. Mine is an 86.5 and the image they have is one with bare metal, like the that was in the car.

So you're saying that nothing will be destroyed running the car without a ground for the coil.

Elias

dr bob

The coils did change with the later cars, telltale is the style of high-tension wire connrctor and boot used. Electrically they are the same.

The ignition coil is a transformer, that converts battery voltage to spark-plug voltage. Primary voltage is applied to one screw terminal, and a trigger from the little solid state drivers on the other screw terminal. The high-voltage side has one side connected common to the switched side of the coil primary, with the other end of that secondary coil connected to the high-tension wire that goes to the middle of the distributor cap. There is no direct ground connection to the coil itself.

eliasmazur

Thanks dr bob. I suspected pretty much that it should not be a problem with the ground. Thanks again for clarifying it for me.

I connected the battery back and the car run great. I drove to the store and when I started up again I could tell that it was running on 4 cylinders. Limped back home and check the connections and found that one of the coil cables I installed was touching the metal pipe from the radiator and shorting. Re-arranged the cable and runs like a charm.

Thanks again for your help.
Elias