Volvo Symptom D12D US02 Service Manual page 77

Group 20
Engine Runs Unevenly at Idle Speed
The following checks should be carried out in order until
the fault is found. These checks also can help eliminate
components with no faults or malfunctions. The number of
tests and the order depends on the following: results from
Related Symptoms
In some cases, other symptoms may be noticed. In these
cases, instructions in other Service Information may be
helpful for fault tracing:
•
Group 20: Starting and Stopping Problems
•
"Step 1: Fault Code Readings" page 74
•
"Step 2: Visual Inspection (System Checks)" page 75
Engine Speed Surges at Low or High Idle
The following checks should be carried out in order until
the fault is found. These checks also can help eliminate
components with no faults or malfunctions. The number of
tests and the order depends on the following: results from
Related Symptoms
In some cases, other symptoms may be noticed. In these
cases, instructions in other Service information may be
helpful for fault tracing:
•
Group 20: Low Power Output
•
Group 20: Starting and Stopping Problems
•
"Step 1: Fault Code Readings" page 77
•
"Step 2: Visual Inspection (System Checks)" page 77
Engine Runs Unevenly or Misfires
Misfires can be difficult to trace but can be caused by:
•
Mechanical faults in the engine.
•
Unstable electrical conditions.
•
Lack of fuel.
•
Poor fuel quality.
Related Symptoms
In some cases, other symptoms may be noticed. In these
cases, instructions in other Service information may be
helpful for fault tracing:
•
"Step 1: Fault Code Readings" page 80
•
"Step 2: Visual Inspection (System Checks)" page 80
•
"Step 3: VCADS Pro Tests" page 81
•
"Step 4: Component and Function Checks" page 82
Engine Speed Surges Under Load or in Normal Operating Range
The following checks should be carried out in order until
the fault is found. These checks also can help eliminate
components with no faults or malfunctions. The number of
tests and the order depends on the following: results from
Related Symptoms
In some cases, other symptoms may be noticed. In these
cases, instructions in other Service information may be
helpful for fault tracing:
•
"Step 1: Fault Code Readings" page 82
D
tests and fault codes, vehicle conditions, vehicle service
and repair history, other symptoms, and information from
the driver.
•
"Step 3: VCADS Pro Tests" page 75
•
"Step 4: Component and Function Checks" page 76
"Uneven Operation, Fault Tracing" page 71
tests and fault codes, vehicle conditions, vehicle service
and repair history, other symptoms, and information from
the driver.
•
"Step 3: VCADS Pro Tests" page 78
•
"Step 4: Component and Function Checks" page 79
"Uneven Operation, Fault Tracing" page 71
The following checks should be carried out in order until
the fault is found. These checks also can help eliminate
components with no faults or malfunctions. The number of
tests and the order depends on the following: results from
tests and fault codes, vehicle conditions, vehicle service
and repair history, other symptoms, and information from
the driver.
•
Group 20: Low Power Output
•
Group 20: Starting and Stopping Problems
"Uneven Operation, Fault Tracing" page 71
tests and fault codes, vehicle conditions, vehicle service
and repair history, other symptoms, and information from
the driver.
•
Group 20: Low Power Output
•
Group 20: Starting and Stopping Problems
•
"Step 2: Visual Inspection (System Checks)" page 83
73