Maintenance manual for sunray hfc4da1-2c china-IV diesel engines
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4) Malfunction Mode
Short-circuit or open-circuit of metering valve; damage of metering valve; contamination of metering valve.
5) Troubleshooting
Use Sunray special diagnosis instrument to check the trouble code and determine the malfunction position. Mainly
check the circuit of metering valve and determine whether there is short-circuit or open-circuit between circuit and the
grounding wire, whether there is short-circuit or open-circuit to power supply, and whether the circuit is consistent
with the given pin definition.
5. Preheating control unit
1) Overview
The preheating control unit is located in the engine compartment and is mainly functioned for the rapid start of engine
under cold state.
2) Working Principle
The preheating control unit is functioned to ensure effective cold start and shorten the warm-up time, which is closely
related to the exhaust emission. The preheating time is a function of coolant temperature. At the start of the engine or
during the actual running, the turn-on duration of the electric heating plug depends on one series of parameters,
including the fuel injection amount and engine speed. The control of the electric heating plug is realized by one power
relay (GCU).
The main part of the electric heating plug is the tubular heating unit. The heating unit is firmly and air-tightly installed
within the electric heating plug housing to guard against corrosion and thermal gas impact. The heating unit is one
Fuel metering unit signal
Fuel metering unit
CP1H and CP4.x metering unit
Fuel amount
Fuel supply to high
pressure pump
Full load fuel amount
Fuel amount characteristic
Idling fuel amount
Ampere
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