- A) Ignition is disabled
- B) Throttle body is closed
- C) Fuel continues to be injected
- D) Fuel and oxygen ignite and keep the turbine up to full speed
"Pops & Bangs" also called "Crackle Map" , "Burble on overrun" or "Schubblubbern" is the sound of fuel detonating in your exhaust manifold when releasing the throttle. We developed this feature in order to keep the turbocharger's rpm up and thus greatly reducing reaction time when you go back on the throttle after a deceleration. Basically it's an anti-lag feature for the turbo, the sound it generates is just an unintended side effect.
To achieve this anti-lag, we keep injecting fuel in the engine after you lift off, this excess fuel isn't burnt in the cylinders as no ignition takes place, but vaporizes in the exhaust manifold and explodes there when it comes into contact with the hot manifold ( thus the "bang" sound ) , there are 2 advantages, the first is that this excess fuel will cool down the cylinder head and the second is that due to the explosion in the exhaust manifold, there is massive energy in the exhaust gasses to power the turbine of the turbocharger and so keep the turbochargers rpm up, even when you're off throttle.
There are however 2 disadvantages to this feature, the first is higher exhaust temperatures, that is why in most cases ( not all ) we do advise to only do this in combination with a decat as the high temperatures could cause damage to the catalyst convertor. The last downside is a small increase in fuel consumption.