Engine swap electronics question

[jimszx]

A good friend of mine has a 2003 Chevy 1/2 ton 4X4 pickup with a 5.3 vortec engine and an automatic transmission. He wants to replace the 5.3 with a 5.7 vortec and transfer all the manifolds and electronics but he's not computer savey and neither am I.

My question is, will the sensors and computer pick up on the increased air volume and increase the fuel as needed or does the computer need to be reprogramed for everything to work correctly?

[dj paul]

would need to be replaced. no way chevy kept the exact same computer in these cars. usually when you pick up a motor you get the computer with it as well.

[jimszx]

Has anyome out there made this kind of switch and if so what did you have to do to the computer?

[strotter]

I've swapped computers around a couple of times, but never the particular one you're talking about. It may or may not be the same PCM, but it will definitely have a different "tune" in the PROM. One of the things the computer has to know is the cylinder volume, which of course you'll be changing, along with a number of particulars related to other engine details. As Paul said, you'll want to swap the computer at the same time as the motor. It may well run (somewhat) with the old computer and sensors, but it will certainly not run as well as it could.

[wingnutthehutt]

Also, if you have to replace the computer with the one from the new motor, THAT computer will most likely have to be reprogrammed for the vehicle. We replaced the computer in a late 90s S10 last week and had to have it programmed to get the VIN numbers in the computer correct.