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Evaluating measured value blocks, display groups 10...29 -Ignition-
Evaluating measured value blocks, display groups 10...29 -Ignition-
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Display group 10 -Ignition-
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▪ Engine running at idling speed
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Read measured value block 10
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⇒
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◂ Indicated on display
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xxxx rpm
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xxx %
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x.x %
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xx.x°BTDC
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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 angle
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6...15 ° BTDC
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---
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Throttle valve angle (potentiometer 1 -G187)
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0.2...4.0 %
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Engine load
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12...26 %
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=> Page 01-136
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Engine speed (idling speed)
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650...750 rpm
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=> Page 01-125
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Note on display zone 3:
Display values must be approx. 100 % when accelerator pedal is fully depressed.
Evaluating display group 10, display zone 2 - Engine load
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Appears on display
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Possible fault cause
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Fault elimination
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Less than 12 %
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- Smaller values can only occur when driving in overrun
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More than 26 %
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- Poor idling (not running on all cylinders)
- Injector or spark plug defective
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Check injectors and ignition system
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- Electric consumers switched on
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- Switch off electric consumers
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- Steering wheel at full lock
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- Set steering wheel to centre position
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- Gear selected (automatic gearbox)
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- Place selector lever in P or N
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- Air mass meter defective
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- Check air mass meter => Page 24-49
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Evaluating display group 10, display zone 3 - Throttle valve angle
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Appears on display
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Possible fault cause
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Fault elimination
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More than 4 %
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- Engine control unit not matched to throttle valve control part
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- Match engine control unit to throttle valve control part => Page 24-153
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- Throttle valve potentiometer in throttle valve control part defective
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- Check throttle valve control part
=> Page 24-57
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- Throttle valve sticking
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- Eliminate cause
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Display group 14 -Ignition- Misfire recognition
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▪ Engine running at idling speed
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Read measured value block 14
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⇒
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◂ Indicated on display
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xxxx rpm
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xxx %
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xxx
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Text
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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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Misfire recognition (active, blocked)
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active
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=> Page 01-138
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Total misfires
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0...6
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---
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Engine load
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15...25 %
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=> Page 01-136
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Engine speed (idling speed)
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650...750 rpm
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=> Page 01-125
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Note on display zone 3:
The total of the detected misfires is displayed here. It provides no information about the time period in which the misfires have occurred. Therefore, check misfire recognition whilst driving .
Evaluating display group 14, display zone 3 - Total number of misfires
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Appears on display
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Possible fault cause
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Fault elimination
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Greater than specification
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- Spark plug defective
- Spark plug connector defective
- Ignition coil defective
- Ignition coil output stage defective
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- Check ignition coils with output stage => Page 28-10
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- Injector defective
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- Check injectors
=> Page 24-89
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Display group 22 -Ignition- Knock control
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▪ Whilst driving
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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.xx %
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xx.x °CA
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xx.x °CA
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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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Cyl. No. 2 retardation of ignition timing by knock control
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0...12.0 °CA
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=> Page 01-142
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Cyl. No. 1 retardation of ignition timing by knock control
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0...12.0 °CA
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=> Page 01-142
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Engine load
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10...100 %
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---
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Engine speed
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630...6800 rpm
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---
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Note on display zones 3 and 4:
The displayed value should be 0.0 °CA at idling.
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Display group 23 -Ignition- Knock control
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▪ Whilst driving
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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.xx %
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xx.x °CA
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xx.x °CA
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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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Cyl. No. 4 retardation of ignition timing by knock control
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0...12.0 °CA
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=> Page 01-142
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Cyl. No. 3 retardation of ignition timing by knock control
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0...12.0 °CA
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=> Page 01-142
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Engine load
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10...100 %
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---
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Engine speed
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630...6800 rpm
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---
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Note on display zones 3 and 4:
The displayed value should be 0.0 °CA at idling.
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Display group 24 -Ignition- Knock control
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▪ Whilst driving
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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.xx %
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xx.x °CA
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xx.x °CA
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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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Cyl. No. 6 retardation of ignition timing by knock control
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0...12.0 °CA
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=> Page 01-142
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Cyl. No. 5 retardation of ignition timing by knock control
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0...12.0 °CA
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=> Page 01-142
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Engine load
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10...100 %
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---
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Engine speed
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630...6800 rpm
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---
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Note on display zones 3 and 4:
The displayed value should be 0.0 °CA at idling.
Evaluating display groups 22...24, display zones 3 and 4 - Retardation of ignition
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Appears on display
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Possible fault cause
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Fault elimination
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All cylinders 12 °CA
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- Knock sensor defective
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- Check knock sensors => Page 28-21
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- Connector corroded
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- Knock sensor incorrectly tightened
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- Loosen knock sensor and tighten to 20 Nm
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- Ancillary components on engine loose
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- Tighten ancillary components
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- Poor fuel quality
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- Change type of fuel
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One cylinder deviates greatly from the others
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- Connector corroded
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- Check knock sensors => Page 28-21
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- Engine damaged
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- Check compression pressures:
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- Ancillary components on engine loose
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- Tighten ancillary components
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Display group 28 -Ignition- knock control
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▪ Whilst driving
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Read measured value block 28
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⇒
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◂ Indicated on display
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xxxx rpm
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xx.x %
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xxx.x °C
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Text
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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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Result of knock sensor test (Test on / Test off / Sys. OK. / Sys. n.OK.
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Sys. OK.
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---
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Coolant temperature
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40...110 °C
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=> Page 01-131
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Engine load
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10...100 %
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---
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Engine speed
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2200...6800 rpm
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---
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