VTEC System Description - Operation
Operating Conditions
At Start
The valve is controlled by the valve lift mode 1 and the intake and the exhaust valve are allowed to operate normally.
At Abrupt Acceleration at Low Vehicle Speed
As in the start, the valve is continuously controlled by the valve lift mode 1 and the intake and the exhaust valve are allowed to operate normally.
At Cruise Running at Low Vehicle Speed
The valve is switched from the valve lift mode 1 to the all-cylinder stop mode. Thus, the operations of the intake and exhaust valves are stopped. The vehicle is allowed to run by the IMA motor torque.
At Abrupt Acceleration at High Vehicle Speed
The valve is switched from the all-cylinder stop mode to the valve lift mode 2. Thus, the intake and the exhaust valve are allowed to operate normally. In the valve lift mode 2, the VTEC system check is performed for about 2 seconds. Then, the valve lift mode 2 is switched to the valve lift mode 1. Then, the intake and the exhaust valve are allowed to operate normally.
At Cruise Running at High Vehicle Speed
The valve is continuously controlled by the valve lift mode 1 and the intake and the exhaust valve are allowed to operate normally.
At Deceleration
The valve is switched from the valve lift mode 1 to the all-cylinder stop mode. Thus, the operations of the intake and the exhaust valve are stopped. Then, just before the timing at which the vehicle is stopped, the all-cylinder stop mode is switched to the valve lift mode 1. Then, preparation for the engine start is performed.
At Vehicle Stopping
The valves prepare for the engine start while still being in the valve lift mode 1.
System Operation
Normal Valve Lift Mode 1 (Default)
Rocker arm oil control solenoids A and B are both off. Engine oil pressure from the oil pump passes the spool valve and the rocker arm. Engine oil pressure is applied to the intake side pistons and the exhaust side pistons. This causes the primary and secondary rocker arms to shift the valves to their normal lift positions.
| Rocker arm oil control solenoid A | Rocker arm oil control solenoid B | Rocker arm oil pressure sensor A | Rocker arm oil pressure sensor B | Rocker arm operation position | |
|---|---|---|---|---|---|
| Normal valve lift mode 1 | OFF | OFF | Low | High | Normal lift position |
Normal valve lift mode 2
Rocker arm oil control solenoid A is off and rocker arm oil control solenoid B is on. Engine oil pressure from the oil pump passes the spool valve and the rocker arm. Engine oil pressure is applied to the intake side pistons and the exhaust side pistons. This causes the primary and secondary rocker arms to shift the valves to their normal lift positions. By turning off rocker arm oil control solenoid A only, the spool valve is changed to normal valve lift mode 2 quickly. It enables the valve lift to change from all-cylinder stop mode to the normal lift position quickly. In this mode, the VTEC system is checked for about 2 seconds.
| Rocker arm oil control solenoid A | Rocker arm oil control solenoid B | Rocker arm oil pressure sensor A | Rocker arm oil pressure sensor B | Rocker arm operation position | |
|---|---|---|---|---|---|
| Normal valve lift mode 2 | OFF | ON | High | High | Normal lift position |
All-Cylinder Stop Mode
Rocker arm oil control solenoids A and B are both on. Engine oil pressure from the oil pump passes the spool valve and the rocker arm. Engine oil pressure is applied to the intake side pistons and the exhaust side pistons. This causes the primary and secondary rocker arms to separate, shift the valves to their pause positions.
| Rocker arm oil control solenoid A | Rocker arm oil control solenoid B | Rocker arm oil pressure sensor A | Rocker arm oil pressure sensor B | Rocker arm position | |
|---|---|---|---|---|---|
| All-cylinder stop mode | ON | ON | Low | Low | Valve pause |