I have an 07.5 L76. Have it tuned w/ Live and bored out throttle body, other than that, its bone stock. It is throwing itself into fail safe mode and shifting extremely hard as well as deactivating traction control. I pulled the code and it said misfire cylinder 7. I pulled the plug out and noticed the tip was bent down as if the piston was slapping it. It was also black w oil as if the cylinder has alot of carbon build up. I took it to the chevy dealership and there saying they dont know exactly what it is, but suspect it is the lifter. Supposedly they are extremely faulty in the L76s. Especially in the Pontiac G8's.

Now I have changed the plug 3 times in the last month, the first time i thought it was bad gas just causing it to foul , but now I know its something more sever. Any suggestions? Lifter u think? and if so how?

 

did it happen after the throttle body??? ive heard some storys about guys porting and polishing the TB and having all sorts of issues

 

swap injectors

 

Tip of spark plug bent down? I don't see that being an injector problem. Black as oil or black with oil? And your warranty is probably expired now huh?

 

The plugs are coming out solid black. I tried putting in a colder plug and it seemed to last a few days longer before fouling and bending. I'm just trying to figure out if its bending down because its getting too hot, or because its definitely getting hit at high rpms. This is a really aggravating issue. I'm just trying to think of anything at all before I pull the heads.

Also, I've noticed a ticking, not knocking sound coming from the area of cylinder 7, I know it is hard to tell where exactly a ticking noise is coming from, but I'm sure its coming from the rear of the engine. ??? ooohh ****....

One more thing too, anyone know if boring out a tb will cause the TPS sensors to go bad? I keep getting P0121 code for the sensor, wonder if cleaning it would fix it? Thanks guys

 

Oh i see what your asking......Im not sure, ill check the fouled plug today and let you know if it actually has oil or if its just str8 carbon

 

can you put your stock tune back in,stock tb and new plugs? This will tell you if you really have a problem.

Who tuned it?

 

When you say the tip is bent down...
If it's actually bent down it's not being hit by the piston that's for sure. Scope the engine!

 

IMO Try this first,

Then try this after wards...then you know if it is something you did or just found a mechanical problem.

Or could this be the start of the infamous #7 destruction that quite a few people have had due to inadequate cooling around that cylinder?

Just trying to help this guy out.

 

Well its funny you say that, because my truck has been running above 210 lately because of a radiator thats goin bad, gettin a new one next week, wonder if that would have anything to do with it?

Also, the #7 plug has oil on it ( not black as oil) black WITH oil. I just changed the oil 2 weeks ago with synthetic, and the oils not black or worn by any means, but the plugs black with carbon and is a little wet with oil when I pull the plug.

Interesting enough, I told you I changed the plug with a colder one.....well it hasn't hurt that plug yet, I thought it did because of the way it was idling so when I went to change it, it was fine! little wet with oil, but not bent down like the other hot iridium plugs I was using. ?????? this is soo wierd