KENR6933 59
Troubleshooting Section
1. Check the air intake system for leakage or
restrictions.
Refer to Testing and Adjusting, “Air
Inlet and Exhaust System”.
2. Check the exha
ust system for leakage or
restrictions. Refer to Testing and Adjusting, “Air
Inlet and Exhaust System”.
3. Repair all defects. Verify that the repair has
eliminated the fault.
Reduced Pres sure of Intake Air
1. If the pressu
re of the intake air at the intake
manifold is lower than normal, either the speed
of the engine will need to be higher or more fuel
must be injec
tedinordertoproducethesame
power. Either of these conditions will increase the
fuel consumption.
Note: Iftheengineisequippedwithawastegate
regulator, low pressure in the air intake will create a
526-07 diag
nostic code.
2. Check the pipe from the outlet of the turbocharger
compressor
totheintakemanifoldforleaks.If
necessary, repair any leaks.
3. Check for th
e correct operation of the wastegate in
the turbocharger. Refer to Testing and Adjusting,
“Turbocharger Wastegate - Test”.
4. If the turbocharger is suspected as being faulty,
replace the turbocharger. Refer to Disassembly
and Assemb
ly, “Turbocharger - Remove” and
Disassembly and Assembly, “Turbocharger -
Install”.
Excessive Valve Lash
Excessiv
e valve lash will cause a change in the
timing of the opening and closing of the inlet and
exhaust valves. Excessive valve lash can cause
a reducti
on of the flow of combustion air into the
engine. Reduced flow of combustion air will increase
the fuel consumption rate.
Refer to the Troubleshooting Guide, “Excessive Valve
Lash”.
Failure of the Primary Speed/Timing
Sensor
If the primary speed/timing sensor fails, the engine
will continue to operate using the signal from the
seconda
ry speed/timing sensor on the fuel rail
pump. The secondary speed/timing sensor is less
precise than the primary speed/timing sensor. Timing
differ
ences between the secondary speed/timing
sensor and the primary speed/timing sensor may
cause an increase in fuel consumption.
1. Use the electronic service tool to check for
active diagnos
tic codes that relate to the primary
speed/timing sensor.
2. If necessary,
replace the primary speed/timing
sensor. Refer to Disassembly and Assembly,
“Speed/Timing Sensor - Remove and Install”.
i02528868
Excessive Valve La sh
Note: This is not an electronic system fault.
Probable Causes
•
Lubrication
•
Valve train components
•
Valve lash
Recommended Actions
Lubrication
1. Remove the valve mechanism covers. Refer to
Disassembly and Assembly, “Valve Mechanism
Cover - Remove and Install” for the correct
procedure.
2. Crank the engine and check the lubrication in the
valve compartment. Ensure that there is adequate
engine oil flow in the valve compartment. The
passages for the engine oil must be clean.
Note: Do not run the engine without the valve
mechanism cover.
Va lve Train C omponents
1. Inspect the following components of the valve
train:
•
Rocker arms
•
Valve bridges
•
Pushrods
•
Valve lifters
•
Camshaft
•
Valve stems
•
Rocker shafts
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