Anti-lag (misfiring) systems...

[YellowMaranello]

When do these fire? When you let up off the gas, push the gas, or both?

[ales]

When you lift

[YellowMaranello]

Originally posted by ales
When you lift

Ah, thanks.

[replicant_008]

Anti-Lag doesn't cause a misfire at all. When you have the car on boost the turbos are spinning with the exhaust gases. Trouble is when you throttle off, less exhaust gas is produced and therefore the impellers slow in velocity - which reduces the initial boost available when you open the throttle - hence lag.

Anti-Lag can work in three ways - directly inject fuel into the exhaust manifold where it burns and creates more gas to keep the impellers spinning (but fraught with issues involving very hot manifolds and fuel being in the same postal code), secondly when you lift off, the ECU retards the ignition but maintains injector rate so some of the fuel passed into the inlet manifold hasn't had time to completely burned by the time it is forced into the exhaust manifold out of the cylinder head - this means you have less power when you lift off but the incompletely burnt fuel gets to expand in the exhaust manifold which provides pressure to keep the impellers spinning, the third is to use a combination of both techniques.

The big issue is heat from the burning gases in the manifold - expect your manifolds not to last, higher underbonnet temperatures and potential to create abnormal heat along the exhaust