Idle Fuelling Trim - 95 My - Aston Martin DB7 Workshop Manual

ffi:
The Aston Martin Lagonda Diagnostic System
Users Guide
Idle Fuelling Trim - 95 MY
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.
Select Idle Fuelling Trim from the Engine Setup
Menu. (The PDU connections are as fortheThrottle
Potentiometer Adjustment.)
1.
3.
StarttheDB7engineand allow itto warm to normal
operating temperature.
Followthescreeninstructionstorunthe idle fuelling
trim procedure.
Observe the bargraphs for oxygen sensors A and B.
The bargraph indications should oscillate evenly
about the 0 % position on the bargraph.
BANK
-100%
BANK
-100%
Idle Fuel Trim
Closed Loop Control Data
Q Idle trim: 8%
9^B 1 1
Oxygen Sensor Fuel Trim 100%
B Idle trim: 5%
— 1 1 1
«^ 1 1
Oxygen Sensor Fuel Trim 100%
Idle Fuelling Trim Display
5. Ifthebargraphindicationsarenotoscillatingevenly
about the 0% position, select the A (cylinders 1, 2
and 3) or the B (cylinders 4, 5 and 5) sensor. The
Increase/Decrease buttons w i l l 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.
September 1996
9-39