Variable Volume Control System (VTCS) (Mazda 6 GG)

The VTCS system operates a valve in the intake manifold to increase the airflow velocity at the intake and create swirls in the combustion chamber to improve atomization of the fuel introduced into the cylinder. This reduces the amount of CH and CO emissions with exhaust gases at low loads.

The PCM activates the VTCS solenoid valve, which closes the valve in the intake manifold 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 - throttle fully open;
• coolant temperature below 63°C.

The PCM turns the VTCS solenoid off to maintain starting performance and stability during engine cranking and for 0.2 seconds after engine cranking.