VTEC/VTC - Operation(K24Z7/K24V7)
VTEC
At Low Engine Speed
At low engine speed, the rocker arm oil control solenoid is turned off by the PCM. Oil pressure from the rocker arm oil control valve does not enter the intake rocker shaft. The primary and the secondary intake rocker arms are lifted by the low lift cam lobe.
Rocker Arm Oil Control Solenoid OFF
At High Engine Speed/High Load Operation
At high engine speed, the rocker arm oil control solenoid is turned on by the PCM. Oil pressure from the rocker arm oil control solenoid enters into the intake primary 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 medium rocker arm, locking the intake secondary and medium rocker arms together. Both intake rocker arms are lifted by the high lift cam lobe.
Rocker Arm Oil Control Solenoid ON
VTC
At Advance Operation
The spool valve in the VTC oil control solenoid valve moves to apply the hydraulic pressure on the advance chamber in the VTC actuator, and then the intake camshaft is operated in the advanced position.
At Retard Operation
The spool valve in the VTC oil control solenoid valve moves to apply the hydraulic pressure on the retard chamber in the VTC actuator, and then the intake camshaft operates in the retarded position.