HydroStream6

iTrader: (16)

On Sunday I changed my plugs as I do at the beginning of every season. I run NGK BR7EF, which is what would be a "TR7" without the protruded electrode. I run them at .025". I've done this for 3 years now with no issues whatsoever. So I take the car for a ride, all is normal. No hiccups, no power loss, no noticeable problems. About 40 miles later I get the misfire code. I figured I didn't seat a wire properly or something stupid. I checked over everything and opened up HPTuners. I was getting a much higher misfire count on #8 than all the others. I swapped wires with 6 and 8 and the problem stayed with cyl 8. I then swapped wires, and coils, and it's still on #8.

Like I said there's no noticeable problem other than the Check Engine Light and misfire count in HPTuners. I might try swapping injectors and see if it follows. I really doubt it's an internal engine problem, as everything was fine before the plug change. I'm tempted to keep driving it and see if it goes away for some reason but it makes me nervous. I'm only showing the misfire at idle it seems as well. Like I said, running 15psi and it's smooth as silk under boost.

Any thoughts? And also just to triple check, #8 in HPTuners is the same as what GM calls #8 correct? Passanger side furthest back? Vehicle is an 04 GTO.

Thanks
Adam

gametech

iTrader: (1)

As unusual as it would be, barring mechanical issues (which I'm sure you would have heard) this almost has to be a coil issue. When all of your expertise is exhausted, go back to things any idiot could check (because that is most likely what we overlook).

EPP

iTrader: (22)

I'd throw a new plug in number eight, possibly you cracked it when you installed it. Bob

HydroStream6

iTrader: (16)

Sorry, I meant to say that I swapped plugs, wires and coils between 6 and 8 and the problem stayed with cyl 8.

HydroStream6

iTrader: (16)

Any more ideas? I threw some meth and some inj cleaner in the tank for the hell of it. I did run my gas tank down pretty low right before the CEL came on, so maybe it did suck up some water and it's pooled in the rail by #8 or something.

SPRAYED 01

iTrader: (22)

It would be wierd becuase its just on 1 cylinder but is this the first tank of the season? Mine runs wierd like that before i go through 2 tanks after a winter.

HydroStream6

iTrader: (16)

it's like the 3rd tank but I don't usually run it that low in the tank

HydroStream6

iTrader: (16)

Oh, I drove it to work today which is like 40 miles so we'll see if the CEL comes back on the way home.

pozesd99'

iTrader: (3)

did you check to see if you cracked the #8 spark plug??? its worth a try, just change it out.....