LS4 V8 Engine Swap

[Leon R]

The issue was that the EVAP system has to be as it was from factory, on the vehicle that the engine came FROM.
It can't throw a CEL, and the EVAP can't be deleted by a tuner.

Agreed! Pretty sure that this is a federal requirement for ALL states! What differs from state to state is the enforcement of such laws!

So, in order to get that to work, the gas tank from the donor vehicle would need to be transplanted into the VX with all EVAP systems attached and functional...

But this is where were we disagree Rules and regulations can be interpreted in many different ways (I am pretty sure that they made a profession out of this ). While your interpretation is correct, it is probably THE most difficult way of achieving desired effect!

Instead of transplanting an ENTIRE fuel system from the donor vehicle you need to understand how EVAP system works in the donor vehicle, compare it to VX's EVAP system and then figure out a way of making they play together! Most of these systems work in a very similar manner, so a simple purge solenoid valve swap might do the trick! Considering that Isuzu used many GM parts, you might even find that the two are compatible.

The bottom line, you want to make GM computer happy and CE light free! There are MANY different ways of achieving this without transplanting 100% of emission controls from the donor vehicle (which is impossible!). Are they 100% legal in a full sense? Probably not, as they weren't designed by GM to work together. But no one is going to apply THAT level of scrutiny to your project!

Have you tried talking to others in your state, who have performed an engine swap?