Boost Pressure Reduction

When the car is driven in 1st or reverse gears the wheels will spin easily if normal turbocharger (TC) control is in operation. To avoid this, boost pressure reduction is engaged at engine speeds under 3,000 RPM and speeds below 10 km/h in first or reverse gears. This applies only to cars with automatic transmission.

The transmission control module (TCM) transmits a signal to the engine control module (ECM) when boost pressure reduction is required. The engine control module (ECM) reduces boost pressure if necessary.

Boost pressure reduction occurs in Winter mode and when the stop (brake) light switch is closed.

Boost pressure can also be reduced to protect the engine from damage. If the knock sensors (KS) detect that the engine is knocking above a given threshold value, and ignition has been retarded and the air/fuel mixture has been enriched, the engine control module (ECM) will reduce the boost pressure until knock ceases.

A reduction in boost pressure also takes place if there is a risk of the engine overheating. If the engine coolant temperature (ECT) sensor indicates that the temperature has exceeded 118°C, the engine control module (ECM) will reduce the boost pressure to reduce heat generation.