How VTEC works and why it's more than just a marketing term. ZTEC, Variable Valve Timing and Lift Electronic Control, is Honda's system that uses two camshaft profiles in one engine. At low RPMs, the engine runs on a conservative cam profile for fuel efficiency and torque. Once the ECU detects high RPM and load, it activates a locking pin in the rocker arms, switching to a more aggressive cam lobe with higher lift and longer duration. This allows more air and fuel into the combustion chamber, in