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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