Low Power Output, Fault Tracing - Volvo Symptom D12D US02 Service Manual

Group 20

Low Power Output, Fault Tracing

Symptom fault tracing
Depending on vehicle configuration, conditions related to
low power output symptoms may be caused or influenced
by specific faults or malfunctions in other vehicle
components such as axles, engine rating, bodybuilder
adaptations, etc. In such cases, also refer to the specific
Service Information for those components.
Note: You must read and understand the precautions
and guidelines in Service Information, group 20,
"General Safety Practices, Engine" before performing any
suggested procedures. If you are not properly trained and
certified in a procedure, ask your supervisor for training
before you perform it.
General Information
Note: During fault tracing, the engine should be run at
the operating temperature as well as at the temperature
where the symptom occurs.
Basic Conditions for Achieving the Correct Tractive Power
The following conditions should be met in order for the
engine to yield the right tractive power:
•
Access to the right amount of energy via the fuel each
time there is injection
•
Access to the right amount of air
•
The engine should emit exhaust gases without any
hindrance
•
The engine should be in a mechanically fault-free
condition
•
The ignition temperature is sufficiently high in the
cylinders
D
"General Information" page 47
For specific symptoms, see:
•
"Sudden Loss of Power" page 49
•
"Gradual Loss of Power" page 49
•
"Engine Does Not Reach Rated Speed" page 50
•
"Low Power After Vehicle Repair" page 50
"Symptom, Fault Tracing" page 3
•
Low power in combination with normal fuel
consumption may have several causes. If no external
symptoms are displayed, check the fuel, air, exhaust
system, compression, the mechanical parts of the
engine, and the engine control system.
•
The engine control system, including sensors, should
be free from faults
Fuel
If the engine is supplied with too little fuel or fuel of a
poor grade, this will have a negative effect on the tractive
power.
Environmental diesel fuels also have a negative effect
on tractive power.
C2002642
47