DTC P1087. Isuzu Isuzu MD F-Series 2004

For 1990-2009 cars only

Makes 🢒 Isuzu 🢒 2004 🢒 Isuzu MD F-Series 🢒 Engine 🢒 Engine Controls - 7.8L 🢒 DTC P1087

DTC P1087 Without RPO CTF

Circuit Description

The pressure limiter opens when abnormally high pressure is generated, releasing the pressure. When the common rail pressure reaches approximately 171 MPa (1,744 kg/cm²), the pressure limiter opens. When the pressure drops to approximately 30 MPa (31 kg/cm²), the pressure limiter works to maintain the pressure, thereby enabling continuous running.

The common rail pressure sensor, installed at left end of the common rail, is used to detect fuel pressure.

A special gasket is used at the connection part with the common rail body so as to seal high pressure fuel.

Conditions for Running

•	The desired idle speed control (ISC) speed, as detected by the scan tool and common rail pressure, is not controlled.

•	DTCs P0091, P0092, P0192, P0193, P1291, P1292 are not set.

•	The crankshaft position (CKP) sensor is in a normal condition.

•	The pump is in normal mode.

•	The battery voltage is more than 8 volts.

•	The engine speed is more than 431 RPM.

•	The engine coolant temperature (ECT) is higher than 60°C (140°F).

Conditions for Setting the DTC

•	The pressure control valve (PCV) opening timing reached the limited value or the feedback value reaches -60 CA degrees.

•	The above conditions are met for 30 cycles.

Action Taken When the DTC Sets

•	The control module will not illuminate the malfunction indicator lamp (MIL) when the diagnostic runs and fails.

•	The ECM limits fuel delivery.

Conditions for Clearing the MIL/DTC

•	The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

•	A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

•	Clear the DTC with a scan tool.

Diagnostic Aids

Inspect for the following conditions:

•	Poor connection at the ECM

Inspect the harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connection.

•	Smoke or power shortage due to the lack of common rail pressure. The pressure limiter is activated.

•	Inspect the fuel filter for a restriction or leak.

Step

Action

Yes

Schematic Reference: Engine Controls Schematics

Important: If the PC sensor or PCV malfunction, repair them first.

Does the DTC set while the ignition is ON and the engine is running?

Go to Step 2

Go to Intermittent Conditions

Inspect for the following conditions:

•	An injection pipe malfunction

•	Inactive pressure limiter

Is the fuel shortage flag set?

Go to Step 7

Go to Step 3

Clear all DTCs.

Does the DTC reset?

Go to Step 5

Go to Step 4

Important: When the PC sensor low pressure output is fixed, DTC P0087 and P1087 will set.

Inspect the ECM connector, the ECM ground, and the pressure control (PC) sensor connector for poor connections.

Did you find and correct the condition?

Go to Step 10

Inspect for an abnormal supply pump or sticking pump.

Did you find the condition?

Go to Step 8

Go to Step 10

Clear all DTCs.

Does the DTC reset?

Go to Step 9

Go to Step 11

Replace the pressure limiter.

Did you complete the replacement?

Go to Step 10

Replace the supply pump.

Did you complete the replacement?

Go to Step 10

Replace the ECM.

Did you complete the replacement?

Go to Step 10

Clear all DTCs.

Does the DTC reset?

Go to Step 1

Go to Step 11

Do any other DTCs set?

Go to Diagnostic Trouble Code (DTC) List

System OK

DTC P1087 With RPO CTF

Circuit Description

The fuel supply system comprises a fuel rail pressure sensor, a priming pump on the supply pump, and pipes. The fuel pressure sensor measures pressure of fuel rail. The fuel supply system sends signal to the engine control module (ECM).

Conditions for Running the DTC

•	The ignition switch is ON.

•	The battery voltage is between 10-16 volts.

Conditions for Setting the DTC

•	The rail pressure is more than 210 MPa (30,748 psi).

•	A pressure fall is carried out quickly.

Action Taken When the DTC Sets

•	The ECM illuminates the malfunction indicator lamp (MIL) and reduced engine power indicator lamp when the diagnostic runs and fails.

•	The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records.

•	The ECM limits fuel injection quantity for fail-safe operation.

•	The ECM limits fuel rail pressure for fail-safe operation.

•	The ECM closes the exhaust gas recirculation (EGR) valve and stops EGR control.

•	The ECM inhibits cruise control.

Conditions for Clearing the DTC

•	The MIL resets when the ignition is turned OFF.

•	A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

•	Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

•	An intermittently sticking suction control valve (SCV) may have allowed the fuel pressure become high enough to open the pressure limiter valve.

•	Normal actual fuel rail pressure readings on the scan with the engine running Park or Neutral at idle are 3 650-5 050 psi (25-35 MPa) and 8 700-18 850 psi (60-130 MPa) in Park or Neutral at WOT, accelerator pedal full travel.

•	A shorted SCV or a short between the high and low control circuit will set DTC P1087 and may not set an electrical DTC P0091 or P0092.

•	An intermittently sticking fuel injector may have allowed the fuel pressure to drop too much. Use a scan tool to perform the Cylinder Power Balance Test for each injector. Verify a consistent engine speed change when commanding each fuel injector ON and OFF.

•	A skewed fuel rail pressure (FRP) sensor value, shifted to a higher pressure, can set this DTC. The actual fuel rail pressure on the scan tool should read 0 psi (0 MPa) with the key ON and the engine OFF after the engine has stopped running for a minimum of 2 minutes.

•

The fuel system from the fuel tank to the fuel supply pump is under a slight vacuum with the engine running. As a result, air can enter the fuel system if these connections are not tight or if there is a crack in one of the fuel hoses. Air in the fuel system will cause fuel rail pressure fluctuations especially at high engine speed and load, which may set this DTC.

Step

Action

Values

Yes

Schematic Reference: Engine Controls Schematics

Did you perform the Diagnostic System Check - Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

Observe the Failure Records for this DTC.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Failure Records.

Does the DTC fail this ignition?

Go to Step 3

Go to Intermittent Conditions

Clear the DTCs with a scan tool.
Operate the vehicle under the conditions to set the DTC.

Did the DTC set?

Go to Step 4

System OK

Perform the fuel system check.
Inspect for a poor connection at the fuel rail pressure sensor.
If a condition is found, repair, as necessary.

Was a condition found?

System OK

Go to Step 5

Inspect the attachment state of a supply pump.
If a condition is found, adjust as necessary.

Was a condition found?

System OK

Go to Step 6

Inspect the fuel pipe.

Stop the engine.
Inspect the fuel line for damage and leakage.
If a condition is found, repair or replace, as necessary.

Was a condition found?

System OK

Go to Step 7

Inspect the fuel injection state of an injector.

Connect the scan tool.
Turn ON the ignition.
Clear the DTC.
Perform the actuator test.
Listen for engine noise.

Change the engine noise?

Go to Step 9

Go to Step 8

Replace the injector. Refer to Fuel Injector Replacement and Fuel Injector Flow Rate Programming .

Is the action complete?

Go to Step 19

Test the signal circuit between the engine control module (ECM) and the fuel rail pressure sensor for the following conditions:

•	An open or short to ground circuit

•	An open or short to battery voltage

Repair the circuits, as necessary.

Did you find and correct the condition?

Go to Step 19

Go to Step 10

Turn ON the ignition.
Observe the engine data on display.

Is the fuel pressure value within the specified range?

0 MPa

Go to Step 11

Go to Step 13

Start the engine
Observe the engine data on display.

Is the fuel pressure value within the specified range?

24-40 MPa (3,626-5,801 psi)

Go to Step 12

Go to Step 13

Observe the fuel pressure in fuel rail.

Bleed the air from the system.
Run the vehicle under the conditions to set the DTC.
Observe the fuel pressure.

Was a condition found?

Go to Step 13

Go to Step 11

Inspect the fuel rail pressure sensor.

Was a condition found?

Go to Step 17

Go to Step 14

Turn ON the ignition.
Inspect for fuel leakage on the fuel line.
Turn OFF the ignition.
Inspect the flow damper noise.

Was a condition found?

Go to Step 15

Go to Step 16

Turn OFF the engine.
Inspect the fuel pipe for leakage.

Did you find and correct the condition?

Go to Step 20

Go to Step 16

Observe the fuel pressure in fuel rail.

Bleed the air from the fuel system.
Perform the actuator test for rail pressure control with the scan tool.
Observe the fuel pressure.

Was a condition found?

Go to Step 18

Go to Step 17

Replace the fuel rail system assembly.

Is the action complete?

Go to Step 20

Review the DTC.

Observe the DTC with the scan tool.
Clear the DTC.
Bleed the air from the fuel system.
Perform the test, run, and review the DTC.

Is a DTC detected?

Go to Step 19

Go to Step 20

Important: The new ECM must be programmed.

Replace the ECM. Refer to Engine Control Module Replacement/Restore Fuel Rate Data .

Did you complete the replacement?

Go to Step 20

Clear the DTCs with a scan tool.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Failure Records.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 21

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

Go to Diagnostic Trouble Code (DTC) List

System OK