Heard something new from a motorsport builder yesterday, coils should be changed every five years for maximum performance and reliability. Anyone else hear of this? And anyone know who the OEM supplier is for Jaguar? Bremi, Bosch, Airtex?

 

Your coils (if original) are almost 10 years old, so much for the five year 'reliability' concern.

Coils either work or they don't work. If they don't work the plug doesn't fire and the result is a 'miss' and probably a P30x code. If you have no such miss or codes, so much for the 'performance' aspect.

Sounds like your guy likes to fix things that aren't broken.

 

+1.

It is funny how you can go to a bunch of shops and you get "opinion" of those that are at the technician level. Some things good, some bad, some urban legends, some old wives tales (or old technicians tale in this case), and then there is truth.

 

If you maintain your spark plugs and wires, your coils will probably outlast you. There are no moving parts and coils are most often burned out due to the two aforementioned items.

Todays plugs are usually good for 100k miles.

 

I suppose coils are baked so can be expected to fail eventually. A few even at 5 yrs, though my 8 coils are at 13.

If you want to reduce the chance they'll fail I suppose you could replace every few years but it's a waste of $$$.

 

The only thing I can come up with is that our pencil coils are sensitive to thermal cycling and age, both of which impact insulation value and can decrease output and longevity.

 

Neither of which are borne out in real life.

 

The coils have a FoMoCo script. I'm not sure how that plays into whether they are good or not since coils in Fords tend to crap out in he earlier 4.6's. Usually when the coil dies it won't spark well at high load.

For some dumb reason I have a cold idle miss since I changed plugs to NGK's from the worn Autolites. I may go back as a troubleshooting step.

 

For what it is worth, it appears the OEMs were made by NGK, no surprise, part number U5082. Considerably less costly than FoMoCo branded coils...

NGK Ignition Coil U5082 | NGK stock code 48267 | Sparkplugs Ltd

 

Not Q&C's Jag, his has NO Ford parts on it, anywhere.