Cam and Valve Mechanism

Variable Valve Timing and Lift Electronic Control System (D15Z1 engine, VTEC-E)

This engine has a normal 4 valve per cylinder valve arrangement. At low RPM, the primary intake valve operates at normal lift while the secondary intake valve opens only slightly to prevent fuel accumulation in the intake port. At high RPM, the secondary intake valve rocker arm is connected to the primay intake valve rocker arm to allow normal valve lift. A synchronizing piston connects/disconnects the two intake valve rocker arms. Hydraulic pressure against a timing piston moves the synchronizing piston one direction, while a stopper piston and return spring moves the synchronizing piston back when hydraulic pressure is released.