Optimax Misfire

[Matt]

Picked up an annoying misfire the other day.
Initially felt fuel related, similar to when the fuel line collapsed and blocked up a while back. Checked filters and seemed OK, although I changed them all as a precaution anyway.

No change.

Then checked the VST and found it spotlessly clean - which was good to see, but didn’t solve the problem.

Misfire gradually getting worse, too. Now it was misfiring at idle - but only when cold, which made it challenging to reproduce.

Anyway, then decided to go through the ignition system.
I reckon this would cause it! Phew. Hopefully problem solved.

[ptm]

Don’t think that hole would help would it!?. Any idea what has caused it though?

[Matt]

Who knows. Could have been a a small slit, or just general aging of the material. And once the spark started jumping, it eroded it into this much bigger hole.

[Andyparky]

Have you sorted it ? I have an optimax , I was told the coils split at the back ? Maybe worth checking

[Matt]

All sorted, the spark plug boot was the issue. I have a spare set of coils if needed, but they all passed the load test so have left them alone.

[Fenlander]

An old days idea on cars for a quick check round the ign was to look at the running engine in the dark.

In the end a nice simple resolution for you.

[Peter_C]

"Water scope" is a tool often used to diagnose misfires. Get a spray bottle and fill it with water. Now spray it on the ignition parts. If it starts misfiring you found your problem. Would have been interesting to see if it would have found the hole in the boot. At least it is an easy fix.

How were the spark plugs? They would always be my starting point, as a different colored plug may quickly lead you to the faulty cylinder.

[Matt]

I’ve not pulled the plugs, but only because the moment I pulled this plug lead off to do a spark test, it was obvious what was going on.