Isuzu 2008MY N Series Workshop Manual page 323

1A-320 Engine Control System (4HK1)
Step
1. Inspect the following conditions:
• An EGR valve gasket that is missing or
damaged
• A sticking EGR valve
• EGR gas leakage any of the EGR
passage between the exhaust manifold
and intake manifold
• Restricted or collapsed EGR passage
between the exhaust manifold and the
EGR valve
• Any type of restriction in the exhaust
system
• Restricted air cleaner element, restricted
or collapsed air tubing between the air
cleaner and the intake manifold
• Any air induction leak
• Any water intrusion in the induction
3
system
• Any contamination or objects that block
the MAF sensor inlet
• Skewed or slow MAF sensor
• Skewed engine coolant temperature
(ECT) sensor. Refer to Temperature vs
Resistance table to test the ECT sensor
at various temperature levels to evaluate
the possibility of a skewed sensor.
• Skewed barometric pressure (BARO)
sensor. Determine the outside barometric
pressure from you location specified in
the altitude vs barometric pressure table.
Refer to Altitude vs Barometric Pressure.
• A sticking intake throttle valve
2. Repair the condition as necessary.
Did you find and correct the condition?
1. Place the transmission in Neutral and set the
parking brake.
2. Start the engine and warm up (arrow engine
coolant temperature to reach at least 75°C
[167°F]).
3. Accelerate the engine between idle and
4
W.O.T (accelerator pedal full travel) many
times while observing the Desired EGR
Position and EGR Position parameter with a
scan tool.
Does the EGR Position parameter follow
within the specified value?
1. Perform the EGR Solenoid Control with a scan
tool several times.
2. Command the Desired EGR Position Increase
and Decrease while observing the EGR
5
Position.
Does the EGR Position parameter follow
within the specified value quick enough?
Action Value(s) Yes
—
Go to Step 13
± 5%
Go to Step 5
± 5%
Go to Step 6
No
Go to Step 4
Go to Step 7
Go to Step 7