In order for the ECU to initiate the VTEC system, 5 engine conditions must be met:

Temperature: The engine must have reached normal operating temperature.
Throttle Position: The throttle must be open far enough to allow for increased airflow in VTEC.
Vehicle Speed: The car must be in motion (wheels spinning).
RPM: Engine must spin to its target value. A GS-R for example starts at 4400 RPM’s.
Oil Pressure: The engine must be operating with normal and safe levels of oil pressure determined by the VTEC pressure switch.