Just finished my lq9 swap but having problems...help!!
 

ok everyone i just finished my 6.0 swap...just to give everyone an update on what i did to my truck... I have an 02 yukon with a 5.3 and i took a 6.0 lq9 and swapped out my tired 5.3 for the lq9

i used only the lq9 block and 317 heads and used everything else off my 5.3

i test drove my truck and it feels sluggish and kinda bogs out on takeoff and when i slam on the gas...when i do this my service engine light is on and starts flashing???
what does this mean??

also i ran the scanner to check the codes on the check engine light and i get a p0171 and p0174 the def is to lean and also p0300 a randon misfire??

not to happy with the end result...not sure what i did wrong or what i need to do to fix this?? please help out guys?

I also have the 5.3 eng comptuter in it...also have the 6.0 computer laying around...would this be an issue...tuning??? should i put the 6.0 computer in it or get it tuned.

Slamming on the gas is usually a bad idea.

It will need to be tuned, but it should run with the 5.3 tune.

You might need to re-check all of the ignition components, especially the wires. They can be broken if care is not taken. Make sure they are all fully seated to the coils. Should feel 2 clicks.

Then, check all grounds while you are in there.

The flashing MIL is due to the PCM picking up a misfire of over 50% or more. It flashes the light to get the driver's attention, as this kind of misfire could potentially damage the cat converters. First thing that you have to do is get the PCM tuned properly, then go from there. As mentioned, check the obvious for that misfire...spark plugs, wires, etc...