Honda Accord 2008 Manual page 356

07/11/02 09:00:44 61TA0000_110_0037
i-VTEC
• The i-VTEC system has a variable valve timing control (VTC) mechanism on the intake camshaft in addition to the
usual VTEC.
This system improves fuel efficiency and reduces exhaust emissions at all levels of engine speed, vehicle speed,
and engine load.
• The VTEC system changes the intake valve lift and timing by using more than one cam profile.
• PZEV model: The VTEC system pauses one side of the exhaust valves in addition to changing the intake valve lift
and timing.
• The VTC system changes the phase of the intake camshaft via oil pressure. It changes the intake valve timing
continuously.
＊２９
Driving Condition
Light-load
Medium/high-load
High speed
HIGH
LOW SPEED CAM
TORQUE CURVE
ENGINE
LOAD
LOW
LOW
VTC Control
Base Position
Advance Control
Advance-Base Position
HIGH SPEED CAM
ENGINE SPEED
For stable combustion the cam angle is retarded, and
reduces the entry of exhaust gas into the cylinder.
Cam phase angle is controlled to optimize valve
timing, improving fuel efficiency and reducing
emissions.
To reduce pumping loss, the intake valve is closed
quickly. This gives the air/fuel mixture a charging
effect that helps to maximize engine power.
HIGH
Description
(cont'd)
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