Turbocharger Wastegate Control System

Turbocharger Wastegate Control System

This system controls the wastegate control solenoid to prevent the turbo from exceeding maximum boost pressure. This system is duty controlled by the PCM. The descriptions A and B are the two conditions of duty. Condition A (maximum duty) and condition B (minimum duty). At other times, the turbocharger wastegate control solenoid controls both the passages from the intake air duct (turbocharger inlet connecting tube), and the intake air duct (turbocharger outlet pipe) to the turbocharger wastegate control actuator.

Condition A (maximum duty):

When the turbocharger boost sensor signal is lower than the upper limit, the PCM turns on (maximum duty) the turbocharger wastegate control solenoid valve, and opens the passage between the intake air duct (turbocharger inlet connecting tube) and the turbocharger wastegate control actuator and closes the passage from the intake air duct (turbocharger outlet pipe) and the turbocharger wastegate control actuator. The pressure at the turbocharger wastegate control actuator is released to the intake air duct (turbocharger inlet connecting tube), and the spring in the turbocharger wastegate control actuator closes the turbocharger wastegate control valve. In this condition, all of the exhaust gas flows to the turbine. This increases the rpm of the turbine, increasing boost pressure.






Condition B (minimum duty):

When the turbocharger boost sensor signal reaches the upper limit, the PCM turns off (minimum duty) the turbocharger wastegate control solenoid valve, and opens the passage between the intake air duct (turbocharger outlet pipe) and the turbocharger wastegate control actuator and closes the passage from the intake air duct (turbocharger inlet connecting tube) and the turbocharger wastegate control actuator. The boost pressure from the intake air duct (turbocharger outlet pipe) pushes the turbocharger wastegate control actuator and opens the turbocharger wastegate control valve. In this condition, only a portion of the exhaust gas flows through the bypass passage bypassing the turbocharger wastegate control valve, and the amount of exhaust gas to the turbocharger decreases. This decreases the rpm of the turbine decreasing boost pressure.