Idle Fuelling Trim Display

This program is used to check and if necessary reset the fuelling level at idle to ensure that the specified idle speed and emission levels are attainable. The throttle potentiometer adjustment sequence must be completed before the fuel trim sequence can be run.

Note: The throttle setup must be completed before attempting to set the Idle Fuelling Trim. An error in throttle stop, throttle cable or throttle pot adjustments can cause serious difficulties in setting the Idle Fuelling.

1. Select Idle Fuelling Trim from the Engine Setup Menu. (The PDU connections are as for the Throttle Potentiometer Adjustment.)
2. Start the DB7 engine and allow it to warm to normal operating temperature.
3. Follow the screen instructions to run the idle fuelling trim procedure.
4. Observe the bargraphs for oxygen sensors A and B. The bargraph indications should oscillate evenly about the 0% position on the bargraph.

Idle Fuelling Trim Display

5. If the bargraph indications are not oscillating evenly about the 0% position, select the A (cylinders 1, 2 and 3) or the B (cylinders 4, 5 and 6) sensor. The Increase/Decrease buttons will appear.
6. Adjust the fuel trim as required to achieve even oscillation about the 0% mark for both sensors. When the adjustment is correct, select the 4 icon and confirm that the idle fuelling trim is correct. On confirmation of the adjustment, the PDU will exit from the idle fuelling program.
7. On completion of the procedure, select Exit from the Engine Diagnostics Software.