G3520B Industrial Engines Caterpillar

Timing Offset

Perform a timing offset calibration for the engine:

1. Remove the timing cover plate from the right side of the flywheel housing. This will expose the engine's flywheel housing timing pointer.

2. Connect Cat ET to the service tool connector.

3. Locate the primary ignition wire at terminal location P4-1 at the slave Electronic Control Module (ECM) that is for the No. 1 cylinder.

4. Clamp the magnetic pickup for a 9U-5358 Timing Light Gp to the wire that is connected to terminal location P4-1. Connect the power leads for the timing light to the engine's battery voltage.

5. Start the engine. Allow the engine to reach normal operating temperature.

6. Bring the engine to high engine idle.

   Note: The engine must be within ±50 rpm of the high idle rpm setting for the engine.

7. Place a load on the engine that is at least 50 percent of the full load. Allow the engine rpm to stabilize.

8. Use the timing light and the timing pointer to determine the actual timing of the engine. Record the actual timing.

9. Use Cat ET to view the status of the "Cylinder #1 Ignition Timing". Record this value.

10. Calculate the difference between the value of the "Cylinder #1 Ignition Timing" and the value of the actual timing.

11. Use Cat ET to enter the calculated value into the "Desired Engine Timing Offset" parameter.

    Note: To advance the engine's actual timing, use positive values for the "Desired Engine Timing Offset" parameter. To retard the engine's actual timing, use negative values for the "Desired Engine Timing Offset" parameter.

12. Allow the engine to stabilize. Use the timing light to verify the correction to the actual timing.

Check the Base Timing

Verify that the base timing is correct. Refer to Systems Operation/Testing and Adjusting, "Ignition Timing - Adjust". Adjust the base timing, if necessary.