I have a 2000 silverado with a 6.0 in it and I just put a different motor in it out of another 2000 because I threw a rod with my other motor. It runs like total crap because its like the timing is way off, kinda like when a distributor is in backwards, but that doesn't make sense because its all computer controlled and supposed to set itself. After I let it run a little bit only my headers on the passenger side got hot. It has spark and the injectors are firing. I've checked my ground wires, put a known good crank sensor in and haven't gotten anywhere. Anybody have any ideas what could be wrong? Thanks in advance for any help.

 

Im assuming you did have the computer retuned for the 6.0?

 

What all did you swap over and what did you keep from the original setup. Is that sides coil harness connected? Knock sensors connected? etc. etc.

 

I would think crank or cam sensor

 

its a 2500 and its always had a 6.0 in it so i swapped in a 6.0 that was exactly the same, it wouldn't have spark without the coil harness connected, n i'm gunna check the cam sensor later today cuz they're a pain to get to

 

Crank relearn? Idle relearn?

Your PCM may still think the old motor with it's learned values is in the truck. When you start swapping things without telling the control module you did something, it controls everything like business as usual.

 

It could have only one of the two coil harness's connected meaning that it's only firing 4 cylinders. I had this happen to me after swapping in my 6.0. One of the harness connectors weren't securely connected and it ran like crap.

 

no it needs more than crank relearn, cuz the way it backfires n stuff it would pry blow up if i would rev it to 4000 like you have to do for crank relearn

 

i've checked the side that is dead n it has spark and is connected

 

I take it this 6.0 you got is used? Did you ever hear it run before you got it?