Effectiveness of the VVTi System

Operation State

Objective

Effect

During Idling

Earliest Timing TDC (EX)

Eliminating overlap to IN reduce blow back to the intake side.

Latest Timing

Eliminating overlap to IN reduce blow back to the intake side.

Stabilized idling rpm Better fuel economy

At Light Load to Advance Side (EX)

Eliminating overlap to IN reduce blow back to the intake side.

Ensured engine stability

At Medium Load to Advance Side (IN)

to Retard Side (EX)

Increasing overlap IN increases internal EGR, reducing pumping loss.

to Retard Side (EX)

Increasing overlap IN increases internal EGR, reducing pumping loss.

Better fuel economy Improved emission control

In Low to Medium Speed Range with Heavy Load

to Retard Side (EX)

to Retard Side (EX)

to Advance Side (IN) 285EG62

to Advance Side (IN) 285EG62

Advancing the intake valve close timing for volumetric efficiency improvement.

Improved torque in low to medium speed range

In High Speed Range with Heavy Load

to Retard Side (IN)

Retarding the intake IN valve close timing for volumetric efficiency improvement.

to Advance Side (EX) 285EG63

to Retard Side (IN)

Retarding the intake IN valve close timing for volumetric efficiency improvement.

to Advance Side (EX) 285EG63

Improved output

At Low Temperatures

Earliest Timing (EX)

Latest Timing (IN)

Eliminating overlap to IN reduce blow back to the intake side.

Latest Timing (IN)

Eliminating overlap to IN reduce blow back to the intake side.

Stabilized fast idle rpm Better fuel economy

Upon Starting Stopping the Engine

Earliest Timing (EX)

Earliest Timing (EX)

Latest Timing (IN)

Eliminating overlap to IN minimize blow back to the intake side.

Latest Timing (IN)

Eliminating overlap to IN minimize blow back to the intake side.

Improved startability

285EG59

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