1995 MX-5 1.8

The car has an eManage & stock ECU with an M45 coldside setup. I’ve been trying to sort a relatively long standing running issue, (car idle spluttered during warmup & didn’t run right in closed loop), which seems to have been a vacuum leak. I’ve resolved this now, by taking the intake manifold off, cleaning everything up and re-sealing & te-torquing all the fasteners. Unfortunately in the process of fixing it I somehow managed to fry the coilpacks.

I’ve now purchased a brand new set of coilpacks – not OEM though, they’re a pattern part – and the car starts perfectly

Unfortunately as soon as it starts it then stalls, after much diagnosis with a scope it turns out that the coils are not outputting a tacho signal. Weirdly te car will also stay running if I pull a lead from cylinder number 1. You also get a hell of a whack from the coils if you touch the coilpack bracket when the engine is running.

There’s barely any movement from the tacho on the dash, but that’s not surprising considering we see nothing of any use coming out of the coilpack tacho output.

I just want confirmation really that this is a faulty set of coils before I go out and spend the GDP of a small country on a brand new set of OEM coils? Could there be a wiring issue somewhere that may cause this? I’ve continuity checked all the major signal wires and they all check out fine.

Cheers

 

Update for searchers:

Replacement OEM coilpack sourced, (2nd hand). Car fires up & stays running.

Pro tip, don't buy pattern part coilpacks.

 

Update for searchers:

Replacement OEM coilpack sourced, (2nd hand). Car fires up & stays running.

Pro tip, don't buy pattern part coilpacks.