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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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5...15 ° BTDC
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---
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Throttle valve angle
(Potentiometer 1 -G187)
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0.2...5.0 %
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Engine load
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10...25 %
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=> Page 01-112
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Engine speed (idling speed)
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750...860 rpm
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=> Page 01-102
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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 10 %
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- Lesser values can only occur when driving in overrun
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- Unmetered air
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- Check intake system for leaks
=> Page 24-34
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More than 25 %
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- Rough idling (not running on all cylinders)
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- Injectors or spark plugs defective
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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 24-34
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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 5 %
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- Engine control unit not adapted to throttle valve control part
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- Adapt engine control unit to throttle valve control part => Page 24-111
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- Throttle valve potentiometer in throttle valve control part defective
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- Check throttle valve control part
=> Page 24-38
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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.x %
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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
(activated, blocked)
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activated
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---
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Total misfires
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---
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---
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Engine load
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10...25 %
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=> Page 01-112
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Engine speed (idling speed)
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750...860 rpm
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=> Page 01-102
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Display group 20 -Ignition- Knock control Cyl. 1 to Cyl. 4
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▪ Whilst driving
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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 °CA
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xx.x °CA
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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 by knock control
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0.0...12.0 °CA
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=> Page 01-117
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Cyl. No. 3 retardation of ignition by knock control
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0.0...12.0 °CA
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=> Page 01-117
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Cyl. No. 2 retardation of ignition by knock control
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0.0...12.0 °CA
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=> Page 01-117
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Cyl. No. 1 retardation of ignition by knock control
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0.0...12.0 °CA
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=> Page 01-117
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Note on display zones 1 to 4:
Display value should be 0.0 °CA at idling speed.
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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.x %
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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 °CA
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Cyl. No. 1: retardation of ignition timing by knock control
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0...12 °CA
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Engine load
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0...100 %
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---
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Engine speed
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750...6500 rpm
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---
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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.x %
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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 °CA
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Cyl. No. 3: retardation of ignition timing by knock control
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0...12 °CA
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Engine load
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0...100 %
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---
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Engine speed
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750...6500 rpm
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Evaluating display groups 22/23, 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 28-15
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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 28-15
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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 sensor test
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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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x.xx %
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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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Knock sensor test (test on, test off, syst.OK, syst.n.OK)
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Syst.OK
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---
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Coolant temperature
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80...110 °C
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=> Page 01-108
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Engine load
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40.0...100.0 %
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---
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Engine speed
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2500...6500 rpm
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---
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