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Checking ignition system
Checking knock control stop
If a fault entry relating to "knock control stop reached" is made, carry out the following checks: Also see measured value blocks 20, 21, 22, 23 and 24; Page .
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Possible causes of fault
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Fault remedy
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Fault entry for all cylinders
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- Poor fuel quality
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- Change fuel quality
(see operating instructions)
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or
Fault entry for all cylinders of one bank
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- Knock sensor tightened to incorrect torque
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- Loosen knock sensor and tighten to 20 Nm
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- Knock sensor defective
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- Check knock sensor => Page 28-39
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- Corrosion on connector
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- Loose components on engine
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- Secure components
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Fault entry for one cylinder
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- Engine fault
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- Check compression
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- Loose components on engine
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- Secure components
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Measured value blocks for ignition timing retardation
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Display group 20, -Ignition- Knock control
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▪ Operation of the vehicle
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Read measured value block 20
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⇒
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◂ Indicated on display
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xx.x°crankshaft
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xx.x°crankshaft
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xx.x°crankshaft
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xx.x°crankshaft
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1
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2
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3
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4
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◂ Display zones
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Specification
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Evaluation
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Ignition timing retardation by knock control, cylinder 4
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0...12 °crankshaft
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=> Page 28-38
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Ignition timing retardation by knock control, cylinder 3
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0...12 °crankshaft
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=> Page 28-38
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Ignition timing retardation by knock control, cylinder 2
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0...12 °crankshaft
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=> Page 28-38
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Ignition timing retardation by knock control, cylinder 1
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0...12 °crankshaft
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=> Page 28-38
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Note:
The numbers displayed in display zones 1 to 4 represent the actual ignition timing retardation due to the knock control of the individual cylinders. The ignition timing is retarded in °crankshaft (degrees).
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Display group 21, -Ignition- Knock control
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▪ Operation of the vehicle
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Read measured value block 21
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◂ Indicated on display
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xx.x°crankshaft
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xx.x°crankshaft
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1
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2
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3
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4
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◂ Display zones
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Specification
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Evaluation
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Ignition timing retardation by knock control, cylinder 6
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0...12 °crankshaft
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=> Page 28-38
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Ignition timing retardation by knock control, cylinder 5
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0...12 °crankshaft
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=> Page 28-38
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Note:
The numbers displayed in display zones 1 and 2 represent the actual ignition timing retardation due to the knock control of the individual cylinders. The ignition timing is retarded in °crankshaft (degrees).
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Display group 22, -Ignition- Knock control
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▪ Operation of the vehicle
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Read measured value block 22
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⇒
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◂ Indicated on display
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xxxx rpm
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x.x %
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xx.x°crankshaft
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xx.x°crankshaft
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1
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2
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3
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4
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◂ Display zones
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Specification
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Evaluation
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Ignition timing retardation by knock control, cylinder 2
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0...12 °crankshaft
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=> Page 28-38
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Ignition timing retardation by knock control, cylinder 1
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0...12 °crankshaft
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=> Page 28-38
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Engine load
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15...175 %
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---
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Engine speed
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750..0,6800 rpm
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Note:
The numbers displayed in display zones 3 and 4 represent the actual ignition timing retardation due to the knock control of cylinders one and two. The ignition timing is retarded in °crankshaft (degrees).
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Display group 23, -Ignition- Knock control
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▪ Operation of the vehicle
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Read measured value block 23
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⇒
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◂ Indicated on display
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xxxx rpm
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x.x %
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xx.x°crankshaft
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xx.x°crankshaft
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1
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2
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3
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4
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◂ Display zones
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Specification
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Evaluation
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Ignition timing retardation by knock control, cylinder 4
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0...12 °crankshaft
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=> Page 28-38
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Ignition timing retardation by knock control, cylinder 3
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0...12 °crankshaft
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=> Page 28-38
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Engine load
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15...175 %
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---
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Engine speed
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750..0,6800 rpm
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---
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Note:
The numbers displayed in display zones 3 and 4 represent the actual ignition timing retardation due to the knock control of cylinders three and four. The ignition timing is retarded in °crankshaft (degrees).
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Display group 24, -Ignition- Knock control
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▪ Operation of the vehicle
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Read measured value block 24
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⇒
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◂ Indicated on display
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xxxx rpm
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x.x %
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xx.x°crankshaft
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xx.x°crankshaft
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1
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2
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3
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4
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◂ Display zones
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Specification
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Evaluation
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Ignition timing retardation by knock control, cylinder 6
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0...12 °crankshaft
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=> Page 28-38
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Ignition timing retardation by knock control, cylinder 5
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0...12 °crankshaft
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=> Page 28-38
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Engine load
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15...175 %
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---
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Engine speed
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750...0,6800 rpm
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---
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Note:
The numbers displayed in display zones 3 and 4 represent the actual ignition timing retardation due to the knock control of cylinders five and six. The ignition timing is retarded in °crankshaft (degrees).
Evaluation of display group 20/21/22/23/24, - Ignition timing retardation
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Indicated on display
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Possible causes of fault
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Fault remedy
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All cylinders greater than 12 °crankshaft
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- Knock sensor defective
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- Check knock sensor => Page 28-39
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- Connector corroded
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- Knock sensor incorrectly tightened
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- Loosen sensor and tighten to 20 Nm
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- Loose components on engine
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- Secure components
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- Poor fuel quality
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- Change fuel type
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One cylinder deviates significantly from the others
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- Connector corroded
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- Check knock sensor => Page 28-39
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- Engine fault
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- Check compression
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- Loose components on engine
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- Secure components
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