I had the PO300 & PO463. I had no choice but to drive the truck 45 miles to a chevy dealership to have it fixed. The tech pulled the plugs and, oh my god! 5 out 8 had NO electrodes left. Porcilean gone also. Gee, must've been the multiple misfire code. LOL
He said I wouldn't have made it much further. If it wasn't for the fact that the coils are shoving 50K + voltage out of them It would've shut down sooner than it did. Gee, you think? But why is the question.
I had just put these plugs in maybe 3500 miles ago. I felt that the engine had a miss & thought after a 100K & some change they needed to be replaced. My fuel mileage was down also.
So I goes to Schucks/Kragen & ask for a set of plugs for my application.
Get Autolites, Pre-gapped mind you. I checked them and they were at 50. So I figure, allright, since I'm not positive on what the gaps suppose to be.
Then I get a bad batch of fuel, we found small amounts of water in the fuel rail. Not alot, but it was there.
So unknowingly I hook up the trailer & stick a 5K lb. truck on it and start dragging it up hills.
Here's our theory. The bad fuel started it to miss-fire, And having the WRONG plugs in it with too hot of a heat range and not gapped properly,(needs to be 60, not 50) started it pinging & detonating with my foot in it, with a load of course, pulling upgrades.
After the plugs took that initial hit the computer was trying to compensate but it just kept eating the plugs.
So wrong plugs & bad fuel.
I tried to help the truck & my wallet shopping for fuel and what do I get.
A hefty bill.
So we still have a mis-fire on #2, but only at idle. anything above 1000 and the miss is gone. And it's not steady, it's intermittant. Not only can you feel the miss, but the scanner is showing it too. This is the same miss I changed the plugs out for. We swap coils, fuel injecter, new plugs, wire, compression test, valve springs and then finally do a leak down on it thinking an electrode got the valve seat. Nothing!! Everything is good.
We're still scratching our heads on it. But fresh fuel & new plugs and she ran good back home.
It's going back friday for a 4x4 service & trans flush, seatbelt retracter re-call, and the tech say's he'll try to figure out the miss but? Go where? short of pulling the head. If it's only there at idle I can live with that. I say run her till she blows, then you'll find out what the problem was. LOL ( New Long block 6.0's are only 4K according to them.)
The 463 code is a matter of how long do you want to watch your fuel gage go nuts. No real harm to anything, only affecting some components of the fuel evap system.
So there it is. What was cool, I was with the tech the whole time conversing & watching him and learning some things along the way. So I know he did the tests, I watched him.