Papabear

Need some help guys, as I am stumped.

2007 Trailblazer SS, stock LS2. Had some long tubes installed and while they were out, had plugs (NGK TR6), wires (PCMforless.com), and heat socks installed. Also had some trans work done. ANyway, after letting trans break in, decided it was time to put my foot in it.

Got to about 5300 RPM in first and started breaking up really bad, and threw P0300 code for multiple misfire. Then I set my aeroforce scan gauge to monitor misfires, and did it again. This time I noticed about 150+ misfires on cylinder #8.

Moved spark plug wire, still #8 missed. Moved coil pack, still #8 missed. Changed plug, still #8 missed.

Could this be something valvetrain related? I am at a loss at this point.

Thanks in advance.

Papabear

Anybody?

litle88

iTrader: (20)

What is the gap?

I may bs wrong but the tr6's might be too cold of a Plug for your application. That's what I used on my 11.7 compression ratio Ls1 w/heads n cam.

Papabear

TR6's recommended for MY application by my tuner and is the most widely used plug with bolt-ons on a TBSS.

Plugs were gapped to 0.035"

Danny

iTrader: (16)

For a bolton only car I would stick with the factory AC Delco plugs, unless you're running N2O. I didn't start changing my plugs till I swapped my cam. Even then I only stepped up to a TR55. Try throwing some AC Delcos in there and see what happens.

I noticed you said you moved the spark plug wire and coil. Did you swap them out with another cylinder or did you just twist the spark plug wire to make sure it was seated? If not, try swapping plug wires first with a good cylinder. If that does work do the same with the coil.

litle88

iTrader: (20)

+1 on the tr55's or oem plugs, and swap out the new wire to an old wire to see what it does as well.

Papabear

I swapped 8 and 1 wire. Then coil, then plug. And i find it hard to believe that two TR6 plugs are going to act up on same cylinder and none of the other 7 are.

I have totally ruled out ignition, which was the point of this thread. Now from my reading, I suspect and exhaust valve spring or something else valve train related.

Was just curious if anyone else had had this trouble before on LS2 applications.

Thanks for the help.

IDRIVEAG8GT

I know you didn't touch them but swap around the injectors, it is highly possible someone tugged on the wires and pulled one in two or something of that sort. I saw this problem happen once on a TT Z06 that we were helping tune on the HPT board.

IDRIVEAG8GT

Also check your grounds.

litle88

iTrader: (20)

I'd say pull the valve covers off, it will take another 5 minutes after you remove the coil packs and check the springs back there.

Keep us posted.