12b. Injection Pressure Regulator Test

12B. INJECTION PRESSURE REGULATOR TEST

Purpose:
The purpose of this test is to determine if idle stability or low power is caused by a stuck or dirty IPR.

Low Idle Stability (ICP Pressure)
- Check at low idle and EOT above 80°C (176°F).
- Monitor the IPR PID with the scan tool.






Recommended Procedure:

- Connect the scan tool.
- Access and monitor the ICP, IPR, RPM, and EOT PIDs.
- Key ON, engine running.
- Warm the engine until the EOT is greater than 80°C (176°F).
- Operate the engine at low idle speed.
- Key OFF.
- Key ON, engine running.
- Compare the ICP PID data to the graph during engine startup.










- ICP should reach 3.5 MPa (500 psi) within a few seconds of cranking engine.
- A sharp rise in IPR duty cycle should be present followed by a steep rise in ICP pressure.
- Next, carry out a slow neutral run-up in park or neutral to 4000 RPM.

If the ICP and IPR response resembles the figure and the engine runs rough between 1200 and 2300 RPM, carry out the Check Valve Operation Test.

If the the ICP and IPR response resembles the figure and the engine runs rough between 3000 and 4000 RPM, replace the IPR valve and verify the repair. Refer to Fuel Charging and Controls, Fuel Injection Pressure Regulator (IPR) Valve.

If any of the following symptoms are present, go to the High Pressure Oil System Air Pressure Check. Repair any leaks in the high pressure oil system and return to this test to verify IPR operation.

- A slow or unresponsive ICP pressure
- The engine will not start when warm
- The IPR duty cycle is greater then the maximum specification
- Engine does not run rough and the ICP pressure response does not resemble the graph

Possible Causes:
- Debris stuck in the IPR
- Injection control system leak

Tools Required:
Scan tool