2001 Grand Prix GTP Misfire problem...
 

Well my friends 2001 gtp has a little problem it's a grand prix with the l67 engine (3.8 supercharged). Well all of a sudden it started to run like shit...and i mean like shit..put in a gear and runs horrible. So I run to the autoparts store and rent a computer tester. Ran the test, no.6 misfire it said (I can't remember the exact code number). So we start running through the no.6 cylinder. Pull the plug..plug it into my roomates mazda 323, nice beautiful spark. Ok next is the wire, pull it off, has continuity and the right amount of resistance. Switch coilpacks, still not it. I started to search on some forums, seems like lots of people have a cracked head problem...anyone else heard of this or have any ideas?

Sounds like you blew the rings or cracked the head. I'd probably lean toward that second one, as it would be odd to just blow one set of rings so severly that it immediately damages performance without any other misfires, but it's possible. If it leaned out too much, you also could have damaged a piston. I'd say the best bet is to pop off the head and take a look around. I've heard of cracked heads on the L67, and unfortunately you're most likely going to have to replace it.

Yeah, heads CAN be an issue on these engines, it has recently come to my attention. Not typical for a 2001, but rather, the early years. They tend to crack near the valvespring pilot seat (that's Intense's terminology...not mine), and when they take cores, they MUST be from a mid '98 or later for that reason.

Cyl #6 is the right front cylinder, if I remember right. Do a compression check in there, just to verify that. If that's good, then you're probably looking at something a little more serious. Double check fuel as well.

My bad we didn't try switching coilpacks, switch one with one of the oem ones and wham runs like a top.

Aren't easy fixes nice?

thank god we did that switch before taking the time to take off the cover.. still dont understand how this happened.. stupid little things just to piss a owner off