VTEC/Variable Cylinder Management (VCM) System Description (2013-15)
Overview
Front Bank
Rocker Arm Oil Control Solenoid Valve A (Bank 2)
Turns ON/OFF the solenoid in response to the signal from the PCM to switch the oil passage to the rocker arm oil control solenoid valve A (Bank 2).
Front Rocker Arm Oil Control Valve
The internal oil passage is switched by the hydraulic pressure from the rocker arm oil control solenoid valve A (Bank 2), to switch the hydraulic pressure applied to the VTEC switching pistons inside the intake and exhaust rocker arms of No. 4 cylinder.
Front Rocker Arm Oil Pressure Switch
Mounted on the oil passage behind the front rocker arm oil control valve, it monitors the hydraulic pressure inside the VTEC system in the front bank.
Camshaft
The intake and exhaust camshafts of No. 4 cylinder are equipped with the two cam lobes for normal valve lift and for cylinder pause (zero lift).
Rocker Arm (No. 4 Cylinder)
The intake and exhaust rocker arms of No. 4 cylinder have a separate structure for switching between normal valve lift and the cylinder pause using the VTEC switching piston.
Rocker Arm Shaft
The rocker arm shaft has a double-tube structure. The hydraulic pressure from the front rocker arm oil control valve operates the VTEC switching piston inside the rocker arm through the rocker arm shaft.
Lost Motion Spring (No. 4 Cylinder)
While No. 4 cylinder is deactivated (other cylinders are activated), this stops the noise and vibration of the rocker arms that are not activated.
Rear Bank
Rocker Arm Oil Control Solenoid Valve A (Bank 1)/B (Bank 1)
Turns ON/OFF the solenoid in response to the signal from PCM to switch the oil passage to the rear rocker arm oil control valve.
Rear Rocker Arm Oil Control Valve
Switches the internal oil passage by hydraulic pressure from rocker arm oil control solenoid valve A (Bank 1)/B (Bank 1), to switch the hydraulic pressure applied to the VTEC switching pistons inside the intake and exhaust rocker arms of No. 1, 2 and 3 cylinders.
Rear Rocker Arm Oil Pressure Switch
Mounted on the oil passage behind the rear rocker arm oil control valve, this monitors the hydraulic pressure inside the VTEC system in the rear bank.
Camshaft
Has the two cam lobes for normal valve lift and cylinder pause (zero lift).
Rocker Arm
The VTEC switching piston with a separate structure switches the valve lift and pause.
Rocker Arm Shaft
The rocker arm shaft has a quadruple-tube structure. The hydraulic pressure from the rear rocker arm oil control valves works on the VTEC switching pistons inside the rocker arms through the rocker arm shafts.
Lost Motion Spring (No. 4 Cylinder)
While No. 4 cylinder is deactivated (other cylinders are activated), this stops the noise and vibration of the rocker arms that are not activated.
VTEC Camshaft
The cams of No. 4 cylinder in the front bank and three cylinders in the rear bank have two types of cam lobes for valve lift and cylinder pause (zero lift).
VTEC Rocker Arm
The intake rocker arm consists of intake primary and secondary, and the exhaust rocker arm consists of exhaust primary A/B and secondary A/B. The VTEC switching pistons are installed inside each primary rocker arm and the return springs are installed inside each secondary rocker arm.
Rocker Arm Shaft
The front bank rocker arm shaft has a double-tube structure of two oil passages used for operating and deactivating No. 4 cylinder. The rear bank rocker arm shaft has a quadruple-tube (two inner hydraulic pressure lines) structure that consists of four oil passages used for operating and deactivating No. 1/No. 2 cylinders and operating and deactivating No. 3.
Rocker Arm Oil Control Solenoid Valve A (Bank 2)/Front Rocker Arm Oil Control Valve
Turns ON/OFF the solenoid valve A in response to the signal from PCM to switch the hydraulic pressure to the control valve. Thus, this changes the direction of hydraulic pressure applied to the VTEC switching pistons inside the intake and exhaust rocker arms of No. 4 cylinder.
Rocker Arm Oil Control Solenoid Valve A/B (Bank 1), Rear Rocker Arm Oil Control Valve
The assembly of the rocker arm oil control solenoid valve A/B (Bank 1)/rear rocker arm oil control valve is installed on the rear bank cylinder head, and the control valve body serves as a rocker arm shaft holder. It turns ON/OFF the solenoid valve A in response to the signal from the PCM to switch the hydraulic pressure to the control valve. Thus, this changes the direction of hydraulic pressure applied to the VTEC switching pistons inside the intake and exhaust rocker arms of cylinders in the rear bank.
Based on the vehicle speed signal, engine speed signal, engine load signal, throttle aperture signal, and engine coolant signal sent from various sensors, the PCM determines what the lift amount should be and controls the ON/OFF of the rocker arm oil control solenoid. The PCM generates and determines the control amount based on signals from various sensors to subject the VTC oil control solenoid valve to a feedback control.
During 6 Cylinder Mode
With rocker arm oil control solenoids A (Bank 1), B (Bank 1), and A (Bank 2) OFF, the rocker arm oil control valves direct oil pressure. Oil pressure enters the primary rocker arm from the oil passage in the rocker shaft, and it moves the VTEC switching piston, sliding it into the secondary rocker arm, and locking the primary and secondary rocker arms together. The rocker arms are lifted by the camshaft, and all cylinders are active.
During 4 Cylinder Mode
When rocker arm oil control solenoids B (Bank 1) and A (Bank 2) are turned on by the PCM, the front and rear rocker arm oil control valves switch the oil pressure. Oil pressure then enters the No. 3 and No. 4 cylinder's secondary rocker arm from the oil passage in the rocker shaft, causing the VTEC switching piston to slide into the primary rocker arm and against the return spring. This disengages the secondary rocker arm from the primary rocker arm to stop valve activation. The No. 3 and No. 4 cylinder's rocker arms do not move, and the No. 3 and No. 4 cylinders are paused. In the other four cylinders, oil pressure from the front and rear rocker arm oil control valves lock the primary and secondary rocker arms together. The rocker arms are moved by the camshaft, and the four cylinders are active.
During 3 Cylinder Mode
When rocker arm oil control solenoid A (Bank 1) is turned on by the PCM, the rear rocker arm oil control valve switches the oil pressure. Oil pressure then enters the rear bank cylinder's secondary rocker arm from the oil passage in the rocker shaft, causing the VTEC switching piston to slide into the primary rocker arm and against the return spring. This disengages the secondary rocker arm from the primary rocker arm to stop valve activation. The rear bank cylinder's rocker arms do not move, and the rear bank cylinders are paused. At the front bank, oil pressure from the front rocker arm oil control valve locks the No. 4 cylinder's primary and secondary rocker arms together. The No. 4 cylinder's rocker arms are moved by the camshaft, and all front bank cylinders are active.