KENR9126 57
Troubleshooting Section
3. Repair all defects. Verify that the repair has
eliminated the
fault.
Reduced Pressure of Intake Air
1. If the pressure 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 injected in order to produce the same
power. Either of these conditions will increase the
fuel consum
ption.
Note: Iftheengineisequippedwithawastegate
regulator,
low pressure in the intake manifold will
create a 526-07 diagnostic code.
2. Check the p
ipe from the outlet of the turbocharger
compressor to the intake manifold for leaks. If
necessary, repair any leaks.
3. Check for the correct operation of the wastegate
in the turbocharger.
4. If the turbocharger or the wastegate is suspected
as being faulty, replace the turbocharger.
Excessive Valve L ash
Excessi
vevalvelashwillcauseachangeinthe
timing of the opening and closing of the inlet and
exhaust valves. Excessive valve lash can cause
a reduc
tion 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 P rimary Speed/Timing
Sensor
If the primary speed/timing sensor fails, the engine
will continue to operate using the signal from the
seco
ndary speed/timing sensor on the fuel rail
pump. The secondary speed/timing sensor is less
precise than the primary speed/timing sensor. Timing
diff
erences 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 diagnostic codes that relate to the primary
spe
ed/timing sensor.
2. If necessary, replace the primary speed/timing
se
nsor.
i04010463
Excessive Valve Lash
Note: This is not an electronic system fault.
Probable Causes
•
Lubrication
•
Valve train
components
•
Valve lash
Recommended Actions
Lubrication
1. Remove th
e valve mechanism cover.
2. Crank the engine and check the lubrication in the
valve com
partment. 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.
Valve Train Components
1. Inspec
t the following components of the valve
train:
•
Rocke
rarms
•
Valve bridges
•
Pushrods
•
Valv
elifters
•
Camshaft
•
Valve stems
•
Rock
er shafts
2. Check the components for the following conditions:
abn
ormal wear, excessive wear, straightness,
and cleanliness. If necessary, use new parts for
replacement.
Note: If the camshaft is replaced, new valve lifters
must also be used.
Valve Lash
Ad
just the valve lash of the engine.
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