Variable Valve Timing & Lift Electronic Control (VTEC) System

NOTE: On Integra (B18C1 and B18C5), VTEC rocker arms are used for both intake and exhaust valves. On 3.2TL, VTEC rocker arms are used only for intake valves.

VTEC uses 3 different camshaft lobes and rocker arms, synchronizer pistons, and a VTEC solenoid valve. See Fig 1. The 2 low lift cam lobes operate primary and secondary (outer) rocker arms. The high lift cam lobe operates the connecting (middle) rocker arm. The PCM controls VTEC solenoid valve which in turn operates synchronizer pistons.

At low speed, primary and secondary rocker arms control valve timing, lift and duration. The connecting (middle) rocker arm remains disengaged, and has no effect on engine operation. At high RPM with heavy engine load, PCM activates VTEC solenoid valve to apply oil pressure to synchronizer pistons located in primary and secondary rocker arms. This locks primary, connecting, and secondary rocker arms together so they are driven as a single unit by high lift cam lobe on which the connecting rocker rides.

Fig 1: Identifying VTEC Rocker Arms & Synchronizer Pistons (Integra B18C1 Shown; 3.2TL Is Similar)

Courtesy of AMERICAN HONDA MOTOR CO., INC.