At High Engine Speed

At high engine speed, the rocker arm oil control solenoid is turned on by the ECM/PCM. Oil pressure from the rocker arm oil control solenoid enters into the intake secondary rocker arm via the intake rocker shaft, and it moves the VTEC switching piston in the rocker arm.

This causes the VTEC switching piston to slide into the intake primary rocker arm, locking the intake primary and secondary rocker arms together. Both intake rocker arms are lifted by the high lift cam lobe.

Fig 1: Identifying VTEC System Operation Diagram - At Low Engine Speed

Courtesy of AMERICAN HONDA MOTOR CO., INC.