TX Tahoe Z71

iTrader: (28)

NGK TR55 gapped at .055 is what I used for years before I was supercharged.

plow0

Not to sure what the gap is on the new plugs, truck runs great other then throwing a code, time for new o2 censors aswell

craigsix

you need a tuner to tune your truck after installing longtubes.

ForcedTQ

iTrader: (1)

As the poster above said, you need to get the tune dialed in. What was the code that was thrown? Front O2, rear 02 etc???

06SilverBirch

iTrader: (3)

Get the rear 02 sensors tuned out you don't need them. When you put longtubes on it will throw codes. Get a tune or retune and go from there.

plow0

Well trucks back to running like ****... It ran beautifully for a few days then all of a sudden it went back into its old habits missing spitting and puffin black smoke. I'm starting to get pissed off. I start school in a few days and I need the truck to be running problem free. The truck is throwing out a p0300 code again, no idea why this time, all the wires aren't touching anything and has the right spark plugs. Wtf is going on!

ZO6Ted

Pull a wire one at a time and see if each cylinder is hitting or not

Vortec350ss

iTrader: (20)

Did you have any tuning adjustments made? If not, and I doubt you did, then I'd almost guarantee thats the problem. As others have said you need to get a tune for the headers that will remove the rear O2 sensors.

The random misfire means its not limited to one cylinder. Is it possible you melted an O2 wire on the headers? That has happened to me before... that will cause some issues exactly like this.

plow0

Why do I have to tune out the rear 02 censors? And where can I get a tune done,

Note; I live in Ontario Canada

JiggyJay

I think last post is thinking u removed your cats and would have to tune out rear sensors. But if your running cats that work then sounds like the rear o2 sensors might be bad and worth replacing to see if it helps