Intake Port Shutoff

The intake manifold contains two intake ports for each cylinder:

• Charge intake port (with flap)
• Swirl intake port

The charge intake ports can be closed by means of flaps. They are held in the open position by spring force. The position of the flaps is determined according to the performance map stored in the CDI control module. The CDI control module reads signals from the following components:

• Mass air flow sensor
• Charge pressure sensor
• Charge air temperature sensor
• Pressure sensor downstream of air filter
• Accelerator pedal sensor
• Crankshaft Hall sensor

The CDI control module actuates the intake port shutoff motor accordingly with a pulse width modulated signal. This then operates the flaps through linkage. In the lower engine speed and load ranges, all the charge intake ports are closed by the

flaps. The entire air mass enters the combustion chamber via the swirl intake ports only. The resulting high turbulence of the air produces a more effective mixing of the fuel with the air and thus improves combustion as well as reducing the amount of soot particles in the exhaust gas. As the engine speed and load increase, the charge intake ports are gradually opened to provide the best possible relationship between air turbulence and air mass for each phase of engine operation.

 

 

Intake manifold 1 Intake port shutoff motor 2 Linkage 3 Flap

4 Charge intake port 5 Swirl intake port