Sorry about posting ANOTHER LS3 swap thread. I know that Ct$-V just posted about putting an LS3 into a V. But I have a different issue surrounding the swap, and I didn't want to hijack Ct$-V's thread since that issue is kind of heading a different direction from mine. I posted this on LS1Tech already with a little response(it's only been a day), but I figured it wouldn't hurt to post on both sites in case there is a guru on one of the sites and not the other. My issue has to do with using a new LS3 ECM in the car.

I have a 2004 V with 142K miles. I had tossed around the idea of FI, but I see that as being a big problem for my budget. As such, I am now planning on putting in a 376/480 and LS7 clutch and selling the LS6 engine and clutch(that is , if there's anything left of my OE clutch). With any luck I could get another 100K+ miles out of the car.

To start out, I am aware of all of the issues surrounding using the LS6 ECM (Lingenfelter module, multiple adapters, knock sensor tapping, reprogramming, etc.). I'm certainly considering this avenue.

However, I am also very much considering using the ECM that can be supplied with the crate engine. This is honestly the more desirable route for me; I would rather not have to use a ton of adapters in the engine bay to make it work. I REALLY prefer to not have to tap a brand new engine to make old knock sensors work. I would also like to sell the LS6's ECM and pedal with the engine. I figure it might sell a little better that way. Not that a 140K+ mile engine is a hot item or anything.

The issue is with the stuff I've read about the other electronics interacting with the new ECM, particularly with a 2004 V. Things like stability control, instrument readouts, ABS. I've never read anything more specific than "It just won't work." I'm curious as to why it won't work. I'm also curious as to whether or not getting the car happy with the new ECM is easier than getting the old ECM happy with the new engine.

I've investigated the 2004 wiring diagrams associated with the engine vs the 2005 and noticed only slight differences. It would be nice to get my hands on the wiring diagrams for the 06 or 07 to see what differences the LS2 made.

Anyway, if anybody has some experience with this (I know a lot of swaps have happened over the years), I'd love to be enlightened.