Lexus ES300 (1997 year). Service manual — part 9

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ENGINE — 1MZ-FE ENGINE

2. Construction

The configuration of the engine control system in the new 1MZ-FE engine is as shown in the following chart.
Shaded portions differ from the previous 1MZ-FE engine.

36

ENGINE — 1MZ-FE ENGINE

3. Engine Control System Diagram

37

ENGINE — 1MZ-FE ENGINE

4. Layout of Components

38

ENGINE — 1MZ-FE ENGINE

5. Main Components of Engine Control System

Mass Air Flow Meter

The hot wire type mass air flow meter has
been changed to the plug-in type. Its basic
operation is the same as that of the previous
type.

6. IAC (Idle Air Control)

The idle speed has been changed in conjunction with the adoption of the electric cooling fan. When the
cooling fan is at high speed while the air conditioner is operating, the idle speed has been increased from
700 rpm to 750 rpm, thus reducing the body vibration that is caused by the electrical load.

7. EGR Control

In the previous models, an EGR vacuum modulator or a VSV was used to control the EGR gas volume.
In the new model. the ECM regulates the VSV to control the vacuum that is applied to the EGR valve,
thus ensuring an optimal EGR gas volume according to the engine condition and improving drivability.

Construction

1) VSV

The VSV controls the vacuum from the VCV that is applied to the EGR valve, in accordance with the
duty signals received from the ECM.