G424F(FE) Service Manual 282 Appendix
AFR (Air Fuel Ratio) Control
The AFR Control category is divided into two
separate sections, one for LP and a second for
Gasoline, (active on bi-fuel units). Key parameters
for AFR Control include the “Open-Loop”/ “Closed-
Loop” control listing. This description informs the
technician whether the emission system is using
closed loop feedback from the oxygen sensors to
control the AFR delivered to the exhaust catalyst or
using tables in the engine control module for AFR
control in open loop mode.
Both the pre catalyst (pre-CAT) and post catalyst
(post-CAT) oxygen sensor setpoint values are
displayed in Phi along with adaptive learn values.
When in LP mode the FTV (Fuel Trim Valves) duty
cycle is displayed in percent. If the system is running
rich in closed loop, the duty cycle will increase to
lean out the LP mixture to the engine. When in
Gasoline operation the average fuel injector pulse
width is displayed along with each individual fuel
injector signal.
Faults
A brief fault list is displayed in the Fault category.
Active faults display the description of all active
faults—faults that are actively taking place when
connected to the SECM. Occurred faults display the
description of all stored faults. The first five stored
faults of the ten possible fault stored record are
displayed by the three digit fault codes. Definitions
of these fault codes can be located on the DFC
screens.
Fault States
Suspected possible faults are displayed here.
(These may be redundant of the occurred fault list.)
All faults can be cleared from the Clear Faults pull
down parameter. Place your mouse pointer over the
Clear Fault parameter box, then simply click the pull
down arrow and select the Arm option. You have
now armed the clear fault function. Using your
mouse click the pull down arrow again and select
the ClearFaults option. You must select another
area on the screen by clicking that area with your
mouse to complete the Clear Faults function; you
will then see all faults clear. Any faults that are
active will immediately be stored in the fault record.
Different fault actions such as engine shutdown are
also listed in this category. Any fault that causes one
of these actions will be displayed next to the action
itself. Only one fault at a time will be displayed next
to the fault action.
Figure 7 Clearing Faults
Sensors
Key sensor values are displayed in this category.
Oxygen sensor values have been converted to
voltage for easier troubleshooting using a multi-
meter. ECT (Engine Coolant Temperature) will turn
green when the correct engine operating
temperature is reached (75°C [167°F]).
Throttle
The throttle category displays the throttle setpoint,
which is the value the SECM is trying to control the
throttle to. TPS (Throttle Position Sensor) 1 & 2
values are also displayed in percent.
Accelerator Pedal
APP (Accelerator Pedal Position sensor) 1&2 values
are displayed in percent.
Ignition
Camshaft and crankshaft sensor synchronization is
displayed along with a designator for the spark
enable and the actual spark dwell.
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