Popis chyby v anglickem jazyce:
As inputted rail pressure sensor signal, ECM of Commom rail diesel engine controls Fuel pressure regulator valve(intergrated 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 limiting 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.
P1186 is set when rail press. is lower than target rail press. by 500~150bar for more than 1.0 sec. in condition that rail press. is controlled by Fuel pressure regulator valve. This code is due to 1)less than intended fuel supply to common rail or 2)excessive return of fuel supplied to common rail or 3)short to low voltage line in fuel press. sensor.
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.
1) Specification : FUEL PRESSURE MEASURED : similar to "FUEL PRESSURE-TARGET"
FUEL PRESSURE-TARGET : 28 ± 5 Mpa
RAIL PRESS. REGULATOR1 : 20 ± 5%
INJ. PUMP REGULATOR : 40 ± 5%
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"shoult be monitored carefully. Although "FUEL PRESSURE MEASURED" is similar to "FUEL PRESSURE-TARGET", if "RAIL PRESS. REGULATOR1" 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" parameter on the Scantool.
1) 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
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.