The run down... I just put an lq4 block with a turbo, comp cam xr265, #60 injectors in my truck. Its throwing a code p 0300 multiple misfire. I changed out the plugs, coil packs and spark plugs. The plugs are tr6 4177 gapped to 29. I did have it tuned on the previous 5.3 and turbo and was told that the tune would very close. Is it possible the tune?

 

Po300 is the pain in the *** code. Check to see if your intake has a leak.check make sure all 8 injectors are clicking. Fuel pressure test. Compression test...clean tb and maf also, that's all i can think of right now

 

Did you have a cam in the 5.3?

 

Man I hope it has nothing to do with compression that sounds to serious. I've cleaned the TB and the Maf im got to do a little research on how to do the other test.

 

No just the 60# injectors and the turbo.

 

how much boost are you running? when i went from 6 to 10 i needed a smaller plug gap, could be as simple as making the gap smaller, at least this fixed my po300

 

It very well could be the cam - it is common to need misfire tables tuned because they throw P0300 during low rpm with a cam. If it doesn't have any misfire codes coming in for specific cylinders, and it runs well with no apparent miss, that would be my guess...

 

It needs to be tuned for the setup. Also
Needs a crank relearn. After that your p0300 will be gone.

 

I'm having kind of the same issue. When should the crank relearn be used

 

Iv got a 9.4 pound spring in but since the motors been in ive been staying out of boost.