I've got a 2v 5.4 with 65k miles that has developed a fairly predictable misfire in cylinder #1 when going up a hill. Instead of replacing the stock COP with another stock unit that will probably fail again, I'm considering upgrading all 8 COP's to something with a bit more spunk and perhaps going with iridium plugs for the sake of (hopefully) not having to mess with them again for the next decade or two. Is there a preferred COP 'upgrade' for the old 5.4's or am I just as well off replacing with the stock units?

 

Your only chance for good performance and reliable performance is the genuine Ford parts.

 

Yup. When I had issues with my 03 it was the plugs not the coils

 

You'd be wasting your money. If you need new plugs and boots, install them. If you have a failed COP, replace it.

I guess that's why, after 7 years, those two $15 Rockauto COPs I installed to cure misfires with the OEM COPS, are still working fine....

 

but that doesn’t matter. The forum has declared that Ford OEM is the only path to success. All other paths are wrong and therefore doomed to fail. If the forum has so declared it, it must be so. Woe be to those who challenge the dogma of the forum.

But like you, I’ve been running perfect for years on aftermarket COPs and boots
<GASP!>

 

I may pick up a set of aftermarkets one of these days and go iridium. Yeah, they're expensive, but they're so obnoxious to replace that I wanted to punch the engineers in the spleen when I put new plugs in ~3 years and 20k ago. I'd rather spend some coin and never have to screw with them again.

 

Oem coils on Amazon $220 to your door last time I checked. Stock plugs have always worked the best...
Do what you want but I have heard it all since 2003..

 

171k on my 5.4 super duty , and it's still running all 8 original Ford COP's. So IF one finally fails I'll be buying a new Ford COP and not some crap aftermarket unit. And I only install motorcraft plugs also, ever 30k

 

99 Triton V10 with 166k miles and two new COP's, Motorcraft and Denso, which are the same. Why mess with something that works.

 

All the COP does is step up the voltage pulse.

Say the stock COP has 12v at 10 amps input, and the COP steps it up to 1200v, it'd be 1200v at .1 amps. Either way, it is 120 watts of power. The wattage remains constant.

An aftermarket COP might step up the voltage even more, but at less amps. Say it jumps the voltage to 12,000v, you would have .01 amps.

 

The secondary voltage will only rise to the point where the plug fires, it can rise no higher unless the plug gap is increased.