Hyundai: Engine D4FA. Manual — part 132
DIESEL CONTROL SYSTEM
FLA -399
DTC P1185 FUEL PRESSURE MONITORING-MAXIMUM PRESSURE
EXCEEDED
COMPONENT LOCATION
E19BC45C
RPS
Fuel pressure regulator valve
EGNG010K
GENERAL DESCRIPTION
E84FA83C
As inputted rail pressure sensor signal, ECM of Commom rail diesel engine controls Fuel pressure regulator valve(inter-
grated with high press. pump) and rail pressure regulator valve(ntegrated with common rail) in order to maintain optimum
rail pressure according to current engine rpm and load. However when the problem that leads rail pressure to out of target
value intended by ECM occurs due to mechanical or electronical reason, ECM shuts engine down and sets DTC by lim-
iting fuel (stops injector operation) in order to prevent engine from being controlled abnormally. "rail pressure monitoring
error" is the DTC which diagnose 1).supplying state of low pressure fuel and 2).mechanical operating conditions of high
pressure pump and 3). rail pressure regulator valve indirectly based on RPS output voltage and RPS duty. thus, repair
relavant to this DTC requires mechanics the total understand of fuel system.
DTC DESCRIPTION
EF4A2B47
P1185 is set when 1)rail press. is higher than target rail press. by 200bar in condition that rail press. is controlled by Fuel
pressure regulator valve or 2)rail press. exceeds maximum limiting value. This code is due to 1)more than intended fuel
supply to common rail or 2)poor return of fuel supplied to common rail or 3)short to high voltage line in fuel press. sensor.
FLA -400
FUEL SYSTEM
DTC DETECTING CONDITION
E96C514C
Item
Detecting Condition
Possible Cause
DTC Strategy
• Voltage monitoring
Enable Conditions
• Engine running
ThresholdValue
• Rail pressure is above target rail pressure by
more than 200bar at Fuel pressure regulator
valve operating condition.- 400ms
• Rail pressure is above maximum limiting
value(1750bar) at Fuel pressure regulator valve
operating condition. - 120 ms
DiagnosticTime
• Refer to threshold Value
Fuel Cut
NO
EGR Off
NO
Fuel Limit
YES
Fail Safe
MIL
YES
• Fuel pressure regulator valve
(open stuck)
• Rail pressure regulator valve
(close stuck)
• Rail pressure sensor
(Output fixed at high
voltage line)
MONITOR SCANTOOL DATA
EB340AF3
1.
Monitoring rail pressure data
1)
Connect Scantool to Data Link Connector (DLC).
2)
Warm engine up to normal operating temperature.
3)
Turn "OFF" electrical devices and A/C.
4)
Monitor "FUEL PRESSURE MEASURED", "FUEL PRESSURE-TARGET", "RAIL PRESS. REGULATOR1", "INJ.
PUMP REGULATOR" parameter on the Scantool.
Specification : Rail pressure at idle :
FUEL PRESSURE MEASURED : similar to "FUEL PRESSURE-TARGET"
FUEL PRESSURE-TARGET : 28 ± 5 Mpa
RAIL PRESS. REGULATOR1 : 20 ± 5%
INJ. PUMP REGULATOR : 40 ± 5%
Fig.1
Fig.1) Monitor "FUEL PRESSURE MEASURED" at idle after warming engine up.
EGNG010R
DIESEL CONTROL SYSTEM
FLA -401
Check if "FUEL PRESSURE MEASURED"data is similar to "FUEL PRESSURE-TARGET". Not only former
two data but also "RAIL PRESS. REGULATOR1" and "INJ. PUMP REGULATOR"should be monitored carefully.
Although "FUEL PRESSURE MEASURED" is similar to "FUEL PRESSURE-TARGET", if "RAIL PRESS. REG-
ULATOR1" and "INJ. PUMP REGULATOR" is out of specification, it means wear, leakage, stuck of fuel system.
2.
Monitoring rail pressure data at acceleration(loading condition).
1)
Connect Scantool to Data Link Connector (DLC).
2)
Warm engine up to normal operating temperature.
3)
Turn "OFF" electrical devices and A/C.
4)
Monitor "FUEL PRESSURE MEASURED", "RAIL PRESS. REGULATOR1", "INJ. PUMP REGULATOR" param-
eter on the Scantool.
SPECIFICATION :
Idle(without load)
Accelerating(stall test)
Diagnosis
INJ. PUMP REGULATOR
38 ± 5%
32 ± 5%
duty decreases
FUEL PRESSURE
MEASURED
28.5 ± 5 Mpa
145 ± 10 Mpa
press. increases
RAIL PRESS.
REGULATOR1
19 ± 5%
48 ± 5%
duty increases
Fig.1
Fig.2
Fig.1) The position of curser on the graph represents idle data.
Fig.2) Data during acceleration(stall test).
EGNG010S
NOTE
The waveform of fuel pressure regulator valve installed at high pressure pump(fuel detecting MPROP) shows 38%
duty at idle, duty drops to approx. 32% at acceleration to raise rail pressure. Duty drop means the decrease of
current.
→ Fuel delivered to common rail increases as current drops.
The waveform of rail pressure regulator valve installed at common rail shows 19% duty at idle, duty rises to approx.
48% at acceleration to raise rail pressure. Duty rise means the increase of current.
→ If current rises, the returning quantity of fuel deliverd to common rail decreases and common rail pressure rises.
FLA -402
FUEL SYSTEM
Fuel return(to fuel tank)
Fuel supply
(from fuel filter)
Fuel press. sensor
Fuel pressure
regulator valve
Rail pressure regulator
valve
Rail press. sensor
Injector
High press. pump
Low press. pump
Common rail
Common rail return line
Injector return line(below 0.5bar)
High press. pump
return line
High press. pipe
MAX : 1800bar
EGNG014Q
VERIFICATION OF VEHICLE REPAIR
EC4B9224
After a repair, it is essential to verify that the fault is corrected.
1.
After connecting Scantool select "DIAGNOSTIC TROUBLE CODES(DTCs)" mode.
2.
Clear recorded DTC using Scantool.
3.
Drive the vehicle within DTC "Enable conditions" in "General information".
4.
After selecting "DIAGNOSTIC TROUBLE CODES(DTCs)" mode and check if DTC is recorded again.
5.
Are any DTCs recorded ?
YES
▶ Go to the DTC guide of recorded NO. in Scantool.
NO
▶ System operates within specification.
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