Boost pressure reduction

The charge pressure is reduced when driving in first gear and reverse with engine speed (RPM) below 3000 RPM to reduce the risk of wheel spin. If the engine has an automatic transmission the automatic transmission receives information from the TCM about when reduced charge pressure is required, for example when shifting. If the car has a manual transmission the Engine Control Module (ECM) determines which gear is selected based on the transmission and final drive gear ratios, engine speed (RPM) and vehicle speed.

On cars with automatic transmission there is also boost pressure reduction in the winter mode.