Intake air mixing control system (VTCS)

The VTCS actuates a flap in the intake manifold to increase the intake airflow rate and create swirl in the combustion chamber to improve the atomization of the fuel introduced into the cylinder. This reduces the amount of CH and CO emissions in the exhaust gases at low loads.

The PCM activates the VTCS solenoid valve, which closes the intake manifold flap when the following conditions are met:

• engine speed - below 3750 min^-1;
• throttle opening angle - below 1500 min^-1 - throttle closed, between 2000 min^-1 and 3000 min^-1 - 26–29 %, above 2500 min^–1 - the throttle valve is fully open;
• coolant temperature is below 63°C.

The PCM turns off the VTCS solenoid to maintain cranking and stability at engine start and for 0.2 seconds after engine start.