66 KENR9126
Troubleshooting Section
Recommended Ac
tions
Fuel Quality
1. Check the fuel quality.
2. If unsatisfac
tory fuel is found, perform the following
procedure.
a. Drain the fue
lsystem.
b. Replace the fuel filters.
c. Fill the fuel system with the correct type of fuel.
d. Prime the fu
el system.
3. If the fault is not eliminated, proceed to “Valve
Lash”.
Valve Lash
1. Refer to Troubleshooting, “Excessive Valve Lash”.
2. If the fau
lt has not been eliminated, proceed to
“Electronic Unit Injectors”.
Electro
nic Unit Injectors
1. With the engine speed at a fast idle, use the
electro
nic service tool to isolate one cylinder at
a time. Note if there is any reduction in engine
speed. If a reduction in engine speed is not noted,
the iso
lated electronic unit injector is not operating
under normal conditions. If the isolation of a
particular cylinder results in a reduction of engine
speed
that is less than normal, this may indicate
that the electronic unit injector is operating below
normal performance.
2. Remove the electronic unit injector from the
suspect cylinder.
3. Install a new electronic unit injector.
4. Repe
at the test in 1. If the noise is still apparent,
remove the replacement electronic unit injector
and install the original electronic unit injector.
5. If the fault has not been eliminated, proceed to
“Pistons”.
Pistons
1. In
spect the pistons for damage and wear. Replace
any damaged parts.
i04010491
Poor Acceleratio n or Response
Probable Caus
es
•
Diagnostic codes and event codes
•
Flash file
•
Throttle si
gnal
•
Fuel rail pressure
•
Electrical connectors
•
Electroni
c unit injectors
•
Intake manifold (boost) pressure sensor
•
Air inlet and exhaust system
•
Fuel supp
ly
Recomme
nded Actions
Note: If the problem only occurs under certain
conditi
ons, test the engine under those conditions.
Examples of certain conditions are high engine
idle, full load, or a specific operating temperature.
Troubl
eshooting the symptoms under other
conditions may give misleading results.
Diagn
ostic Codes and Event Codes
Certain diagnostic codes and/or event codes may
cause
poor performance. Connect the electronic
service tool and check for active codes and/or logged
codes. Troubleshoot any codes that are present
befor
e continuing with this procedure.
Note: Although a sensor's signal may be in the
oper
ational range of the sensor, certain failure modes
of a sensor may produce an output signal that does
not represent an accurate measurement. Use the
elec
tronic service tool to check that the pressures
and the temperatures are fluctuating normally.
Also check that the values are reasonable for the
con
ditions that are present.
Flash File
Verify that the latest flash file has been installed into
the Electronic Control Module (ECM).
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