Tools Required
| • | Injection Pump Wrench |
| • | njection Pump Adjustment Tool |
Important: Do not perform this procedure when only an injection pump has been replaced
(refer to Injection Timing Adjustment).
This procedure should only be used when a DTC has directed you to do
so, or one of the following repairs has been performed:
| • | The engine has been replaced. |
| • | The front engine cover has been replaced. |
| • | The PCM and the Injection pump have been replaced at the same
time. |
| • | The crankshaft position sensor has been replaced. |
The PCM has the ability to perform a TDC Offset learn when one is not
present or has been cleared. This procedure allows the PCM to be updated with
the correct TDC offset for the vehicle.
Important: The TDC Offset specification is only to be used after the Learn procedure
has been performed.
Application
| TDC Offset
|
All
| - .25 to - .75
|
Learning a TDC Offset
- One of the above repairs must have been performed. If not, do
not continue. Refer to On Vehicle Service for repair that was performed.
- Install the scan tool.
- Start the engine.
- Operate the vehicle until the engine coolant temperature is greater
than 77°C (170°F).
- Clear all DTCs and turn the engine off.
- Turn the Ignition ON with the engine OFF.
- Hold the accelerator pedal in the wide open throttle position
for a minimum of 45 seconds (the TDC Offset value in the scan tool will clear
to 0.00 when this step has been complete) and then release the pedal.
- Turn the ignition OFF for 30 seconds. In this step, the
PCM powers down (to verify the PCM has powered down, a No Communication With
Vehicle screen will display when trying to access a data list.
Important: After approximately 2 minutes, a new TDC Offset will learn.
- After the PCM has completed the power down, start the engine.
Important: Verify in the scan tool that ECT is greater than 77°C (170°F).
If not, operate vehicle until desired ECT is achieved (vehicle can be driven
or throttle can be depressed until correct coolant temperature is achieved).
- When the ECT is greater than 77°C (170°F) and the engine speed
is below 900 RPMs, the PCM automatically learns a new offset in approximately
2 minutes (a momentary stumble in engine rpm will indicate that the
TDC Offset has been activated).
- Check the TDC Offset in the scan tool. The TDC Offset should be
between -0.25 and -0.75. If the TDC Offset is within the specified
value, the procedure is complete, If not, continue to the next step
(adjusting the injection pump).
- Turn the engine OFF.
- Loosen injection pump flange nuts using the injection pump wrench.
Important: In order to achieve a negative (-) TDC Offset number rotate the pump
towards the drivers side of the vehicle.
In order to achieve a positive (+) TDC Offset number rotate the pump
towards the passenger side of the vehicle.
- Slightly (1 mm equals 2 degrees) rotate the injection
pump in the desired direction (use the injection pump adjustment tool.
- Repeat steps 3 through 14 until correct TDC Offset has been achieved.
It is possible that the injection pump may require multiple adjustments to
achieve the specified value.
Important: If you are unable to set the correct TDC Offset or the TDC Offset will
not learn, check for the following:
| • | Check to see if coolant temperature is greater than 77°C (170°F). |
| • | Check to make sure the proper time intervals are adhered to for
wide open throttle, PCM power down and the learn timer. |
| • | Check all PCM and injection timing stepper motor connections and
for DTCs. |
| • | Check the Techline terminal/equipment for the latest software
version. |
| • | Check for proper base installation of the injection pump (injection
pump ESO solenoid should be approximately straight up and down). If base timing
is greater than +/- 2.0 degrees (from 3.5°), set base timing to 3.5
(use Time Set) degrees and then try to relearn and offset. |
| • | If the TDC Offset is stuck on a high + (plus) value, check for
a damaged camshaft driven gear key. |
| • | If the TDC Offset is stuck on a high - (negative) value,
check for a damaged or improperly installed crankshaft position sensor. |
| • | If all checks have been performed, the injection pump may be malfunctioning,
however, this is an extremely unlikely failure. |
