I have a 2005 Sierra and I just did an LQ9 and built trans swap, tuned with HP Tuners. Since I have done the swap the only code I'm throwing is a P0300 Random Misfire. I have new plugs and wires. The coils are from the original L33. The engine is built by LSTurnkey and has 470 hp with a bigger cam. I can't figure this out. My next step is new 02 sensors? Any suggestions would be awesome. Thanks!

 

With having the cam in it you may have to get turn the misfires turned off or at least change the sensitivity of the misfire codes. Aside from that ive seen leaking intake gasketscause misfire on the engines but usually the first few really cold days and normally there will be p0172/p0174 lean codes along with the random misfire code....

 

It's definitely just the P0300 consistently. I spoke to my tuner yesterday and he said he can turn that off. I'm hoping that is the issue. It's the only thing holding me from getting inspected and I was up in June.

 

Where you live that an engine light will fail you??

 

Pennsylvania. Emissions is a bastard up here. I own a house in Portsmouth, VA. I should just register it there.

 

Yes you should.... Lol no emissions down here!! As far as state inspections go check engine lights dont matter, so long as you have cats and all the "emissions" equipment!!

 

I actually bought the truck down there when I got out of the Navy. Oh yea, it has Kook's long tubes and catted Y pipe. Not gonna re-register it down there though.

 

I would love to find the $1500 for set off kooks with cat pipes, just too expensive for me at moment.... Kickin myself for spending the money on factory style ss cats and manifolds at this point! But was less expensive option at time and was in a rush

 

I know the feeling. When I did the LQ9 and built trans swap I wanted to get it on the road so bad. After ordering everything, it took about 2 weeks or so working in my back yard after work to get it done. Pain in the *** but its road worthy now. The headers are pricey but man they were worth it. I've already done one trip to Portsmouth in the truck and I'm doing another on Monday back down there. Truck runs great except the gas mileage lol

 

Thats one thing i noticed with mine, when i took it to get tuned after it was all back together it was about a 250mile ride at about 85-90 whole way, used about 7gallons one way but around town, yeah not even tryin to calculate that.... Id be depressed!!! Lol i need look into better cam and get this tb converter ive had sitting in passenger floorboard for about two months now in the front of the tranny, sure tgat might help cuz right now its dog to get moving!!