Coil Pack failure?

[ianredtopsprint]

Hi, I have been running megajolt lite on my redtop powered dolomite sprint for a few years now.

Now having a strange problem with it.

It runs fine for about 30 minutes then starts to miss badly. It not like a miss on a single cylinder, its like the whole spark is lost and the engine becomes violent in operation, it then develops over a few miles to become undriveable and eventually shuts down. Leave it for 10-15 minutes and then its starts up again fine and runs again for a period of time before missing badly again.

I initially thought it was a failed VR sensor so changed that for new. No improvement.
Then changed the coil pack lead and plugs for new (coil pack and leads fro Trigger Wheels). It has a 1st generation coil pack. Again no improvement. So changed EDIS module (from trigger wheels again) and still no improvement.
Reset VR sensor and made sure it is firmly fixed.

Ran using the view software and it appears to lose rpm signal and then regain. I don't know if this is a VR signal issue of just a response from the EDIS. Tacho drops violently as well - this is being run from pin 11 of EDIS module.

So running out of options now.

It feels like a coil pack failure with it perhaps being temperature related. All other components have been replaced ie VR sensor EDIS, Coil Pack, Leads, Plugs.

Any additional ideas would be helpful to resolve this annoying issue.

Thanks in advance.
Ian

[brentp]

I would definitely try a different coil pack; they do fail and when they do, it often shows up as degraded performance, not just a failure to run.

Let us know what you find out. thanks!

[ianredtopsprint]

Hi, thanks for the reply. That's my thinking as well, so I have ordered a new coil pack from a different manufacturer and will test this in the next few days and provide some feedback.

Thanks
Ian

[ianredtopsprint]

Well I changed out the coil pack from a different manufacturer and the problem is still there. So its not the coil pack.

One niggling thing I had was the loss of the rpm signal to my smiths rev counter when the engine starts to miss (its fed from pin 11 of the EDIS). I also see the rpm signal on the Laptop run view dropping when the problem rears its head, so I am now more inclined to think it is speed sensor/wiring related. The EDIS unit was swapped for a spare so I know it is not that.

So next stage would be to replace speed sensor and connector and wiring to the EDIS connector.

Remember it is a hard shutdown I experience, not a loss of one cylinder firing.

Other than that I can't see what else it is unless its losing an earth somewhere intermittently or the PIP signal is lost to the ECU through interference/poor connection?

Ian

[brentp]

It could be the sensor losing sync at a particular point in the rev range. Often this happens if the sensor starts vibrating on the bracket; this can be solved with making the bracket more rigid, and closing the gap between sensor and trigger wheel.

What does it look like using a timing light when it happens?

[ianredtopsprint]

Changed sensor, wiring and connector, relocted bracket so it was firm against the engine block and problem has gone away. The screened cable i originally used was very thin and i suspect was damaged easily either through vibration at the connector or poor connection to start off with. I now have a stronger single core wire cable instead of a thin stranded type. Makes a much better connection to the connector pin. Ran for 50 miles with no problems.

[brentp]

Nice job. Great you figured it out, and thanks for closing the loop and updating us.