P0088
2GR-FSE ENGINE CONTROL: SFI SYSTEM: P0088: Fuel Rail / System Pressure - Too High
P0088 - Fuel Rail / System Pressure - Too High
DESCRIPTION
The high-pressure fuel system consists of the spill control valve, pump plunger, check valve, relief valve and fuel pressure sensor. The spill control valve opens and closes the low-pressure fuel line (from the fuel tank), the pump plunger (operated by the camshaft) pressurizes fuel, the check valve mechanically opens and closes the high pressure fuel line (to the fuel delivery pipe), the relief valve prevents fuel pressure from becoming extremely high, and the fuel pressure sensor located on the fuel delivery pipe monitors fuel pressure.
The fuel pump for high pressure is installed to the cylinder head cover (bank 1) and is driven by the cam located at the rear end of the exhaust camshaft.
The plunger moves up and down by the camshaft rotations, and produces a vacuum to suck fuel and pressurizes the fuel. This fuel then pushes the check valve open and flows into the fuel delivery pipe. The ECM opens and closes the spill control valve to regulate the fuel pressure to the target fuel pressure of 4000 to 13000 kPa (40.8 to 132.6 kgf/cm2, 580 to 1885 psi). In order to obtain and maintain the target pressure, the ECM monitors the fuel pressure using the fuel pressure sensor and performs the feedback control.
If the internal fuel pressure of the fuel delivery pipe exceeds the standard pressure of 15.3 MPa (156 kgf/cm2, 2219 psi), the fuel relief valve installed on gateway of the fuel delivery pipe discharges the fuel pressure and then returns the fuel back to the fuel tank.
MONITOR DESCRIPTION
If the fuel pressure does not decrease even after the ECM commands the high-pressure fuel pump to open the spill control valve, a DTC is output.
If there is minimal difference between the fuel pressure before and after the fuel relief valve operates, a DTC is output.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
TYPICAL MALFUNCTION THRESHOLDS
CONFIRMATION DRIVING PATTERN
1. Connect the Techstream to the DLC3.
2. Turn the engine switch on (IG) and turn the Techstream on.
3. Record the Freeze Frame Data.
4. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure) Reading and Clearing Diagnostic Trouble Codes.
5. Turn the engine switch off and wait for 30 seconds.
6. Turn the engine switch on (IG) and turn the Techstream on.
7. Based on engine rpm, engine load and other freeze frame data stored in the ECM, reproduce the conditions present when the DTC was stored.
8. Enter the following menus: Powertrain / Engine / Trouble Codes.
9. Read the DTC.
HINT
- If a DTC is output, the system is malfunctioning.
- If a DTC is not output, perform the following procedure.
10. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
11. Input the DTC: P0088.
12. Check the DTC judgment result.
HINT
- If the judgment result shows ABNORMAL, the system has a malfunction.
- If the judgment result shows NORMAL, the system is normal.
13. If the test result is INCOMPLETE or UNKNOWN and no DTC is output, perform a universal trip and check for permanent DTCs Reading and Clearing Diagnostic Trouble Codes.
HINT
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.
INSPECTION PROCEDURE
HINT
Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.
PROCEDURE
1. CHECK OTHER DTCs OUTPUT (IN ADDITION TO DTC P0088)
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG) and turn the Techstream ON.
(c) Enter the following menus: Powertrain / Engine / Trouble Codes.
(d) Read the DTCs.
Result:
HINT
If any DTCs other than P0088 are output, troubleshoot those DTCs first.
B -- GO TO DTC CHART SFI System
A -- Continue to next step.
2. PERFORM ACTIVE TEST USING TECHSTREAM
(a) Connect the Techstream to the DLC3.
(b) Start the engine and turn the Techstream on.
(c) Enter the following menus: Powertrain / Engine / Active Test / Control the Target Fuel Press / Fuel Press.
(d) Check that the fuel pressure fluctuates when the target fuel pressure changes.
HINT
The Active Test operation lowers the target fuel pressure by 12.5% or increase the target fuel pressure by 25%.
OK:
Fuel pressure fluctuates.
NG -- REPLACE FUEL PRESSURE SENSOR Removal
OK -- Continue to next step.
3. REPLACE FUEL PUMP ASSEMBLY (FOR HIGH PRESSURE)
(a) Replace the fuel pump assembly (for high pressure) Removal.
NEXT -- Continue to next step.
4. CHECK IF DTC OUTPUT RECURS (SEE IF DTC P0088 IS OUTPUT AGAIN)
(a) Connect the Techstream to the DLC3.
(b) Turn the Techstream on.
(c) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.
(d) Start the engine.
(e) Enter the following menus: Powertrain / Engine / Trouble Codes.
(f) Read the DTCs.
Result:
B -- END
A -- REPLACE ECM Removal