Miami British says they are absolutely Champion OEM manufactured for Allmakes. That's still cheaper than AB and I saw the 8-pack going for over 90 and $100 all over the web so its not like I regret it. If I had more experience with ignition replacement I would have gone a different route but this is where I'm at. Thanks for your input, everyone

 

Actually if they are copper core champions those plugs will be shot long before 100k miles I replace mine every 20k admittedly you could probably go to 40k.

 

Oh that's why you don't spend $80. You have to replace them every 10 months

 

Closer to 6 months but yeah in the last year of ownership I put 37k on my DII

 

Yep 80.00 for Copper Core plugs is nuts.... I don't care who their made by and I don't care if their OEM.... As long as the plug you replace your old worn OEM Copper Core plugs with has the same heat range honestly the brand is no longer important. I went with Platinum/Iridium because they will make it to 100K vs a Copper Core Plug that WILL NOT.

NGK, Autolite, AC Delco, Denso all make good spark plugs. I would however avoid Bosch as their Platinum/Iridium/Double Platinum/X2/X4 Tip plugs are known to quickly fowl and cause misfire faults (when I was new to LR's I tried a set of X4 Tip Bosch in my 97 RR HSE 4.6L Vitesse & 3K later I was having all sorts of misfire faults...). Removed a plug and found it completely fowled...

 

I ran Bosh platinum with out issue for years, though I now run E3's

 

I made sure they were all gapped right under .040

Ran great for the first 100 miles but ever since I started the engine after work yesterday I have P1300, cyl 6 misfire, cyl 7 misfire and flashing CEL. I sprayed carb cleaner around vaccum lines, double checked my HT leads on coils and plugs. I don't know what happened. Didn't even misfire with the old stuff before I upgraded. Maybe air getting by the plenum gasket? I have messed with it for hours and done everything but pull the IM back off

 

Check all your wire leads, at the plug/coil, and if you can install the old plugs or go buy some cheap copper plugs locally and see how it runs with those. I'd never slap a non-labeled plug in any of my vehicles.

 

Ok I guess I will do that

 

I always put some rtv on the plenum gasket before I reinstall the intake manifold. Helps buckets.