Not everything on a V12 is a mystery. Sometimes the faults are very ordinary. What you're about to read is a bit of a nothing-burger, actually.

The engine developed an unmistakable misfire. I could feel it most just coming off idle. Plus I heard that characteristic "bump bump" sound at the tailpipes and the exhaust was smelly. It felt like an old-fashioned secondary ignition misfire.

I began by pulling plug wires off the distributor cap one at a time to determine, hopefully, which cylinders were misfiring. It didn't take long to find a fault. Even slightly jiggling the wires produced a visible arcing between wires and the characteristic snapping sound. Plus, one of the wire was arcing to the coil bracket. So, the plug wires were "leaking" and needed replacement.

I decided, on a "Oh, what the hell?" basis, to go ahead and replace the spark plugs at the same time. I couldn't remember how old they were and my records didn't show any replacements since 2015-2016 when I installed the engine. Same for the plug wires.

New plugs, new wires....and the engine has return to "Smooth as a baby's bottom" operation

Four or five of the plugs showed signs of slightly rich running. This makes me wonder if I have a problem developing with some of the injectors. Unfortunately, and stupidly, I didn't keep the removed plugs in order so as to identify, for the future, which injectors might be in question. Oh well.

For wires I used Standard Motor Products #55454. These seem like decent wires, fit well, and were labeled with cylinder numbers. Less than $40 delivered from Rock Auto.



I know some will argue the wisdom of using lower cost plug wires. The faulty wires were a lower cost set purchased off Ebay for about $50 as I recall.

Many tout Magnacore wires as the way to go. I cannot deny that they are very high grade. But also very expensive, about $180 last time I checked. Personally I'm not sure if the cost-versus-longevity is worth it but that's s decision each of us makes on our own.

Anyhow, all's well. About 4 hours to do the work and about $70 all-in for plugs and wires. That's fairly painless as old V12 Jags go!

Cheers
DD

 

Oh, how I miss my V-12! Like a turbine!

 

Well cone Doug.

Simole things these V12's,really simple.

Magnecor WAS my flavour, cheap enough in the 90's, then the bean counters got involved, and doubled overnight.

10 years for HT leads in that hell hole of the V is acceptable to me, and at $40, who cares.