Turbo Adjustment

Turbo Adjustment

The airflow from the turbocharger is regulated by a solenoid valve, which controls the exhaust turbine wastegate pneumatically.





The solenoid valve (179a) is supplied voltage from the main relay (229) and is grounded from control module pin 14(A) with a 32 HZ PWM. The wastegate valve goes opposite the closing direction when the pulse ratio increases, thus increasing compressor flow.

When the requested air mass/combustion (torque) is too great to be regulated by the throttle alone, the turbo control must satisfy the excess requirement. The excess is converted to a PWM that controls the charge air control valve.

ECM calculates the necessary (requested) boost pressure to achieve the desired engine torque.

The values for atmospheric absolute air pressure and intake air temperature are used to correct the conversion. At low atmospheric pressure or when the intake air temperature is high, a greater PWM ratio is required to obtain the same engine torque.





The control module checks that the actual boost pressure agrees with the requested one. If necessary, the PWM ratio is fine-tuned by being multiplied by a correction factor.

The correction factor (adaptation) is stored in the control module memory and is always included in the calculation of the PWM ratio.

The purpose is to make actual torque and request torque the same as soon after a load change as possible.