1 Intake manifold flap vacuum unit
2 Intercooler bypass flap vacuum unit
3 Intake manifold flap solenoid valve
4 Intercooler bypass flap solenoid valve
5 PCM
The intake manifold flap has another function in addition to restricting the intake air for exhaust gas recirculation and closing the intake system when the engine is stopped. During the regeneration phase, the intake manifold flap closes off the air flow via the intercooler, depending on requirements. At the same time, the uncooled charge air is fed via the intercooler bypass flap. Adjustment of the intake manifold flap is performed by the intake manifold flap solenoid valve via vacuum. During the regeneration phase, the intercooler bypass flap opens, enabling uncooled charge air to be directed to the combustion chambers. The uncooled air prevents cooling of the combustion chamber at low engine speeds/engine loads and this promotes the regeneration of the diesel particulate filter.
Adjustment of the intercooler bypass flap is performed by the intercooler bypass flap solenoid valve via vacuum. In accordance with the requirements, the solenoid valves are actuated at a specified duty cycle by the PCM. Effects of faults If a fault occurs at one (or both) of the two solenoid valves, limited regeneration is still possible, depending pon how high the intake air temperature is and the operating condition of the engine.
Diagnosis
In the context of EOBD both solenoid valves are monitored for short and open circuit.
Faults to the solenoid valves have very little effect on exhaust gas emissions. Therefore, they are non MIL active components.
Possible diagnostic trouble codes (intake manifold flap solenoid valve): P0488, P0489, P0490.
Possible diagnostic trouble codes (intercooler bypass flap solenoid valve): P0033, P0034, P0035.
