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What can I adjust to lesson a "back fire" from the exhaust on throttle off, 12P tune, methanol & an SC14 blower on the VP engine, we hope to have it back on the rollers on Monday or Tuesday.

Ive had it before on cars with an exhaust leak but its more of a back crackle than a full on back fire.

On the LS1 cars they can disable DFCO to help that.

Decelleration Fuel Cut Off?

That's it. I was talking to a owner of a tune shop in melbourne once who tunes LS motors.
He didn't like the brand of exhaust on my mates car because they popped heaps on decel so he turns of the dfco to stop that.

Mine does it and I hate it, vlad likes it so something tells me when he's got the lap top going in my car he's not pushing the right buttons ! Dam tin foil hat

Im still trying to workout how to make it crackle. Not sure what was different in the V8 tune to make it do that, unless a lack of VSS was the cause. Does it still do it now?

My cars don't do it, but I can induce it by cracking the throttle open 0.01% on decel. its also gives a few crackles on sudden downshift with decel and upshifts on full noise.

Wasn't the vss, that was working last tune we did

must be something different in the v8 tune then.

No DFCO should crackle/backfire more as the fuel isnt being cut and isnt being burnt and enters the exhaust. Increasing the amount of DFCO should lessen or stop it.

So if dfco was left as standard maybe the 20 30 kpa map points could be a bit lean?