lt4vette

Guys, I'm looking for some input. I have a 96 LT4 with a mildly built motor. It has an initial tune with LT1 edit. The issue I am having is the PCM with LT1-edit is from a 96 Fbody with 6 speed that I transplanted for tuning capabilities. It will fire and run for about five seconds before VATS kills the car. I had a new key cut that matches the resistance of the donated PCM, but it wouldn't crank. At this point I'm try to defeat VATS so I can finish the tune. Using my factory PCM is not an option. Thoughts?


Thanks in advance.

THE 383 admiral

if you are capable of re-flashing your 96 PCM. why are you not using the vette Ybody specific calibration? you can easily find this definition online. OR ask someone to read there stock 96 vette PCM and send you the bin. print out. your Fbody tune. and transfer the updated table information. into your now. correct vette specific. PCM & calibration. I have many bins. If i had a OBD 2 bin. I would email it to you.

hcbph

I don't think you're having a VATS issue. If a VATS issue, it won't turn over in the first place, I don't think it comes into play once the engine is running. I'd look more into something like fuel pressure/delivery before I'd suspect the VATS system.

lt4vette

Thanks for the reply. I have confirmed that it is not a fuel pressure/delivery issue. I chased that initially, replacing the filter and pump. It holds 42 lbs or so. The car runs and drives with the stock PCM. The stock one isn't tunable, which is why I'm trying to utilize the Fbody PCM with LT1-edit on it. Also the "security" light flashes just before it dies. That leads me to believe VATS is the culprit.

WVZR-1

It ain't VATS (no crank)

I saw this yesterday and thought it would be interesting "to watch"!

Why is the original "non-tuneable"? That requires some explanation. The 2 cars aren't even similar in vehicle communications (maybe a poor choice of word but .....

It runs with the OE PCM and that maybe confirms my thoughts. The Corvette PCM is communicating with a very different CCM/BCM (call it what you like). The F-body isn't spec'd to communicate with the same CCM/BCM. Can it be done? I've NO IDEA. I ain't that smart BUT it seems very obvious that it's very likely your situation "that you've created"?. I don't even know that with the 2 FSM side by side it could be sorted. Someone very likely knows BUT .. Either the entire CRANK & FE needs removed from both the car and the PCM desired.

Maybe - just maybe you've got a bad PCM or maybe, just maybe a bad tune ....

What is the label on the f-body PCM?

I'd say the hardware isn't compatible ..... You mention the "SECURITY" light so it can be assumed that the CCM is still in the mix.

A quick glance at the CCM-AWAKE/ON/OFF it seems the car is maybe doing just what it is supposed to do. If the CCM doesn't see engine RPM it shuts off in 5-15 seconds. In instances it can do 30 seconds. The CCM isn't going to let the car run until it sees a "VALID" PCM/Engine configuration. You've proved this because the car runs with the correct PCM installed. Can the CCM be programmed for the f-body? Very unlikely. Like I said I just ain't that smart.

Do you have the FSM for the car?

***I would scan the CCM for DTC's and maybe expect a DTC 81 (Invalid Vehicle Configuration)

lt4vette

Thanks for your input. I do have the FSM for the car. And I agree that this is something I've created. The reason is the Fbody PCM has LT1-edit licensed to it, thus making it easy to tune. I just need to bite the bullet and get the software to tune my Ybody PCM.

WVZR-1

The "wallet" can bite you every time - I'd say that's what's needed.

The cut-off is perhaps happening when the CCM finally sees through the communications the "INCORRECT/INVALID" combination and takes action. I didn't look very far to arrive at my thoughts and when I saw you mention "SECURITY" light I just thought CCM.

I actually thought I'd "poke around" looking for "INVALID VEHICLE CONFIGURATION" bypass, in later BCM things can be manipulated but I don't know that the CCM in '96 could be manipulated. It required programming when replaced but modifying after an initial programming I'm unsure of.

Purple92

IF it was a VATS issue - I think you can turn the VATS "off" in the PCM programming. I say that because that's what I did on my 92. But as others have said - VATS problems prevent the starter from getting power - so if your starter is turning the car over - you don't have a VATS issue.