Coil pack melting

[RickHaleParker]

I have noticed the heat spreads from the end nearest the connector plug, but still no idea why. Next thing to check must be the ecu.

Excess heat indicates excess current.
1. Have you checked for heat with the coil pack disconnected?
2. Have you checked the wiring for shorts?
3. Short in connector? Sometimes the connector walls between the pins acquire a defect.
4. Are you using IR thermometer to pinpoint the source of the heat?

[abscate]

4. Are you using IR thermometer to pinpoint the source of the heat?

+1000 points for this, Rick

[StephenG]

Only gets hot when the engine’s running and the coil pack is connected. Wiring and connectors renewed- all ok. No shorts or breaks. Does need a thermometer, you can feel it with your finger as it spreads. Still to check, trigger wire coil pack to ecu continuity and find if wire 3 still has 7ohms to ground. Also must check if it gets excessively hot with the ignition left on but not running.

[StephenG]

Hi Abscate and Rick, looked a bit more this evening b4 it got too dark. Checked the signal wire continuity, all ok. The coil only gets hot when running and the 7 ohm reading from 12v feed to ground is on the feed side to the fuse so unlikely to be relevant. Next question- will the coil pack get hotter with the signal wire shorted to ground or if permanently live. Answers on a postcard....

[StephenG]

Have got a spark on all 5 plugs, though on the toasted coil it was weak/erratic, but ok with a good coil. Can’t run it for more than a few minutes as it will melt and I’m running out of coil packs. Most of the coils I’ve used have been second hand,

[RickHaleParker]

Your Wire colors and test points?

[darrylrobert]

could a faulty spark plug be to blame? i wouldnt be putting new coils, use the old ones to test. Remove the plug and inspect inside the chamber

[darrylrobert]

could it be dry firing, ie not fuel? that might cause it to heat up? You may need to check the wiring for continuity.

[StephenG]

Hi the diagram is close, my car doesn’t use pin 2, as it’s a turbo, and my trigger wires are A31,30, 50,52,50 respectively from no1, there are lots of different combinations of trigger wire nos. on various sites, I found my version on Matthewsvolvo so assume it’s a correct line up. I don’t think it’s dry firing because it overheats far too quickly. Last evening I found the crank sensor has been put in place with silicone so I have to sort that, but that should not affect one coil pack, unless someone knows otherwise

[abscate]

Wait

What is the resistance of number 3 pin on the connector to ground? That’s on the secondary side of the coil.