well a few weeks ago had some issues with the truck running really rough and felt like it was missing I scanned the truck and it came up with a cylinder missfire code .I changed the plugs out for a new set of NGK tr6's and it was better smoothed itself. today went out for a drive and it started to do the same thing rough idle no engine light yet ..what could this be maybe a bad coil pack ?my plug wires are new msd 8.5mm
Could too much fuel make this happen any thoughts on what i should try next ? I don't have Atap and where i got it scannend my buddies shop he just has a simple scanner
I don't wanna go to the dealer
but i might have too though
Can i unplug plug wires while the truck is running to figure out which cylinder it is that is running rough or will i do damage doing that ?

jim

<small>[ August 31, 2002, 10:35 AM: Message edited by: GMC SKI ]</small>

 

Maybe you could pull the plugs and see of one is fouled. If one is then check that wire/coil pack.

 

Shouldn't hurt anything to unplug them while it is running...except you! Go ahead and grab one of those suckers and unplug it and be prepared for a nice jolt <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> . Hint: get a pair of WELL insulated pliers and then wear some thick leather or rubber gloves and after all that you may not get the crap knocked out of you. Yes, I'm speaking from experience. Oh, make sure the pliers don't have a small break in the insulation anywhere <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> !