Is there anything a tuner would have to do or know when creating a stand alone tune for this motor? It is a stock high output 347 hp version. The reason I ask is I have two pcm's by different tuners with programming to run the motor only and both fire the spark out of time. I've checked all wiring and grounds, changed cam and crank sensors, and can't find anything wrong. Motor misfires and back fires thru the throttle body.

 

Coil harnesses crossed up?

 

yep, I checked for that and injector harness too. Both are on the correct side. Thanks for the suggestion. Got everything done in the swap and can't get it started.

 

You may need to load another OS to the PCM, maybe the one currently loaded is not the proper one. I have had to do it a few times

 

must confess, I'm a newbie to LS motors and programming. My HP tuner should be here Thursday or Friday. Is the OS something the HP tuner can load? hope so. Trying to avoid further tuner costs.