Ignition coil / cracked spark plug

[evenflow]

Any guesses as to the cause of a failed ignition coil and cracked spark plug?

[Mr2Mike]

Which part of the plug is cracked? If it's the outer porcelain part then it's through abuse, someones had a socket on it and put too much sideways pressure. If it's the inner part of the insulator, then it could be from someone trying to gap the plug incorrectly or possibly detonation damage, or even something the engine has ingested.

Coils can fail without warning, especially modern pencil coils that sit directly onto the plug. Marginal design, poor manufacture and very harsh operating conditions all contribute the the relatively high failure rate of these items.

Edited by Mr2Mike on Wednesday 1st December 20:46

[stevieturbo]

As above. Plus some people can be a bit brutal and break the coils during plug changes.

[evenflow]

Thanks for the replies. Not sure where the plug was cracked, only have vague info from the garage at the moment.

[Pigeon]

Mr2Mike said:

Coils can fail without warning, especially modern pencil coils that sit directly onto the plug. Marginal design, poor manufacture and very harsh operating conditions all contribute the the relatively high failure rate of these items.

And you have one per cylinder and they cost a fking fortune compared to old traditional works-with-a-distributor kind of coils. I never liked the idea from when I first heard about it because it was a given that poorly-manufactured designs which were marginal for the very harsh operating conditions would be the order of the day, and I liked it even less when I saw how much the things cost.

[Mr2Mike]

Pigeon said:

Mr2Mike said:

Coils can fail without warning, especially modern pencil coils that sit directly onto the plug. Marginal design, poor manufacture and very harsh operating conditions all contribute the the relatively high failure rate of these items.

And you have one per cylinder and they cost a fking fortune compared to old traditional works-with-a-distributor kind of coils. I never liked the idea from when I first heard about it because it was a given that poorly-manufactured designs which were marginal for the very harsh operating conditions would be the order of the day, and I liked it even less when I saw how much the things cost.

I know what you mean, but then again distributor caps and rotor arms tend to have problems with the very high voltages that modern ignition systems need to generate - the contacts in the the distributor cap of my MR2 would get eaten away in no time. The wasted spark systems seem a reasonable compromise providing you have an even number of cylinders, but even then the coils seem quite prone to failure.