rawbee

Hello, so I am in the middle of a 5.3L swap and have manage to piece together everything as far as harness goes. The harness i got was from a 6.0L (as far as what i know) so im assuming that means the pcm that i got with the harness is also a 6.0L pcm. The motor i am using is a 5.3L genIII bored over to ls1 standard 3.905. the question here is after installing everything and running my wiring for fuel pump, drive by wire, etc. will i be able to just turn key and hope for a easy start up? or will i need to get my pcm flashed for the setup that i am running?

codyvette

iTrader: (24)

3.898 is standard bore for an LS1. It will probably start and run but it should be tuned if you want it to run right.

LSX Power Tuning

iTrader: (4)

I am assuming this is for an engine swap in a non factory ls vehicle. It will not start without getting VATS deleted in the pcm. With just VATS deleted it will run but you will have a long list of codes. Even its a stock motor you will need a tune to make it run 100% right.

codyvette

iTrader: (24)

I always forget about the VATS. Now that I think more about it, if the injector info doesn't match the injectors it probably won't idle.

07kyeringt

I would delete vats and tune it.