Civic L4-1.8L (2006)
Variable Valve Timing Solenoid: Description and Operation
VTEC System
-
This mechanism improves fuel efficiency and reduces exhaust emissions at all levels of engine speed, vehicle speed, and engine load.
-
The VTEC mechanism changes the valve lift and timing by using more than one cam profile.
-
The VTEC system changes the cam profile (angle) at cruising speeds. (Cam angle is changed to obtain the EGR effect and reduce pumping loss).
Operation
At engine start, and high load
-
The rocker arm oil control valve is OFF.
-
Oil pressure enters secondary rocker arm B from the oil passage in the intake rocker shaft. This forces the VTEC switching piston into secondary
rocker arm A against the return spring and disengages the secondary arm A from the secondary arm B to stop valve actuation.
