Volkswagen CJDA Workshop Manual page 134

3
Industriemotoren - Industrial Engines 2009 ▶
Workshop Manual for Diesel Engine (2.0 l/36-75 kW_EA 189) 05.2015
◆ The injection system provides idling speed smooth running
control. There may be differences in performance between
the individual cylinders (component tolerances, jet flow rate,
compressions, etc.) which are recognised and compensated
for by selective injection quantities.
◆ Recognition at idling speed is via the signal from the engine
speed sender. If the signals are delivered at the same
rhythm then all cylinders work the same. If one cylinder is
weaker then the crankshaft takes longer for the next half rev-
olution. Conversely a more powerful cylinder will accelerate
the crankshaft so that less time is needed for the half revolu-
tion.
◆ If the engine control unit recognises a difference, then the
relevant cylinder is immediately given more or less fuel, until
the engine runs "smoothly" again.
◆ +... mg/stroke: The respective cylinder is less powerful and
is therefore supplied with more fuel.
◆ -... mg/stroke: The respective cylinder is more powerful and
is therefore supplied with less fuel.
6.3.11 Display group 20 - Fuel rail values 3
Test prerequisites
● Engine running at idling speed.
● Engine warm, coolant temperature not below 80°C.
● Intake air temperature < 40°C.
Display Operating mode or component
zone
1 Engine speed
2 Pressure in high-pressure fuel system
(specified)
3 Pressure in high-pressure fuel system
(actual)
4 Regulating valve for pressure in high-
pressure fuel system
Evaluation: display group 20, display zone 3 - pressure in
high-pressure fuel system
Display shows Possible cause of fault
Deviation from
◆ Defective fuel pressure sender -G247-
specification
◆ Fuel pressure regulating valve -N276-
◆ Fuel metering valve -N290- defective
◆ Fuel pump defective
Evaluation: display group 20, display zone 4 - regulating
valve for pressure in high-pressure fuel system
118 Repair Group 01 - Vehicle self-diagnosis
defective
Specification
880...1090 rpm
320...780 bar
320...780 bar
25...42 %
Fault remedy
⇒ P age 394
– -G247- Check.
⇒ P age 391
– -N276- Check.
⇒ P age 388
– -N290- Check.
⇒ P age 314
– -V393- Check.
Evaluation
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⇒ P age 118
⇒ P age 118