L67 swap PCM issue

[Quaraxkad]

but it sounds like it won't even start in the first place.

It will start and run for a coupe of seconds on the 04 Impala PCM. It will start, run, and drive on both the 98 Lumina LTZ and 00 Grand Prix GTP PCM. Unfortunately I need the Impala PCM due to the transmission incompatibility.

One thing to consider is the MAP sensor. An L67 PCM expects to see a 2 bar MAP sensor. An L36 PCM expects to see a 1 bar MAP sensor. I once put an L67 PCM into an L36 car without changing the MAP sensor. I had purchased a 2 bar MAP sensor but I just forgot to swap it in. It would not start. Once I removed the 1 bar MAP sensor and replaced it with the 2 bar, it started right up.

I am using the MAP sensor that came on the engine, 12580698, google search suggests it is in fact 2bar.

It's possible that your tuning software never actually disabled VATS in your 2004 PCM. I know when I've done it, several values had to be changed and it was not intuitive at all, but I'm not familiar with the software you are using.

That's very possible. However if that's the case, then both TunerCAT and TinyTuner are incapable of disabling VATS. I have tried both. Are you able to download the 2004 Impala SS Stock.cal attached to my first post and disable VATS in whatever software you use?

EDIT: I forgot to mention, I did try hooking up C2-23 to a hot-on-crank source, and that had no effect.