okay this is the 2nd time my truck started mis firing. the last time i changed all my plugs and all looked great except the passenger side in the back the procelin ring on the inside was cracked and part missing. I use NGK TR6 plugs gapped at .032. Well this time i pull the plug and the inside procelin is cracked again and the end is broke off. Current mods are SBTB,Cold Air, Chip/tune,4lb lower pully,plenum. Here is my dyno http://ursone.com/dyno/IMG_0002.JPG
Question is should i change the gapping on the plugs and if so to what? Should i just take it back to the shop and let them figure out why this plug is getting messed up? Any help would be great.
Thanks
David

 

If I had to guess, the reason that the plug is damaged is the cylinder is running lean and the plug is getting to hot . I would possibly suspect that you have a clogged or damaged fuel injector on that cylinder. Check the primary fuel filter aswell. your gapping is a bit tight, but I would not suspect that as being the problem. I run a 6lb'er and gap the TR6's @ .036.

 

please excuse my ignorance,but are your plugs platinum?if they are i just had a similar issue and a real good fix.

 

NGK TR6's are a copper core 'race' type plug that is one step heat range colder than the stock plug.

The TR6's are the same plugs that many L-owners run, either the TR6's or the denso's seem to be the prefered plugs.