Isuzu KB P190. Manual — part 335

EXHAUST SYSTEM 6F – 7

GENERAL DESCRIPTION

This system controls the formation of NOx emission by recirculating the exhaust gas into the combustion chamber
through the intake manifold.

4JA1T(L):
The two EGR valves are controlled by two Vacuum Switching Valve (VSV) controlled by EGR controller according to
signals from various sensors.
The amount of EGR depends on the number of engine rotations and the opening of the accelerator.

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6F – 8 EXHAUST SYSTEM

4JA1TC/4JH1TC
The EGR system engine is controlled by ECM. Refer to “Engine driveability and emissions” section for detail.

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EXHAUST SYSTEM 6F – 9

EGR SYSTEM DIAGRAM 4JA1T (L)

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EGR System Operation

Inspect EGR valve motion visually while changing engine RPM under no load condition after warming-up.
• Inspection point (Engine RPM)

RPM Idling

900

∼ 960

2000 3250

Engine Front Side VSV-1

ON

ON

ON

OFF

Engine Rear Side VSV-2

ON

OFF

ON

OFF

ON means VSV should receive signal to move EGR valve.

OFF means VSV shouldn’t receive signal to move EGR valve.

6F – 10 EXHAUST SYSTEM

4JA1TC/4JH1TC

The EGR system engine is controlled by ECM. Refer to “Engine driveability and

emissions” section for detail.

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