Closed-Loop Test - Kubota WG1605-E3 Diagnostic Manual

WG1605-G-E3,WG1605-L-E3,WG1605-GL-E3, DM

Closed-Loop Test

Tests the closed-loop fueling feedback system to
verify that exhaust gas oxygen sensors are properly
functioning and are providing reliable information. The
test runs in the order defined below and aborts if at any
time an error/fault is identified, the throttle input is
elevated, or the operator requests the test to STOP.
Aborting the test due to identification of an error/fault
requires that the service technician addresses the
identified error and then repeats the test to fully validate
the system.
1. Enable Strategy and HEGO Sensors (CL Test
State= Pre-cat init test)
a. The test mode is entered by selecting START from
EDIS. Once initiated, the user must acknowledge
two prompts prior to the test running. These prompts
require that the vehicle be in neutral or park and
notify the user that the engine speed will increase to
run the test. Answering YES to both of these prompts
will initiate the test.
a. Govern engine to × RPM as defined in the
calibration.
NOTE
• Test disables if FPP % exceeds the % used in Idle
Speed Command Test (Tidlspd_FPP_max)
b. Turn all configured EGO heaters on according to
'EGOZ Heater-Control Target Impedance / Voltage
Limit Schedule'.
NOTE
• EGO heater control during this phase uses the
run time and heater impedance target schedule,
including the heater voltage limits, until the
heaters are operating at the final impedance
target.
c. CL pre-cat test status will indicate "Test Running"
through steps 2-3.
2. Pre-Catalyst EGO Heater Diagnosis (CL Test
State= Pre-cat heater & pre-cat power test)
• The purpose of this portion of the test is:
1. To validate that the pre-catalyst EGO heater
element(s) are capable of heating the sense
element(s) to a useable state.
2. To validate that the pre-catalyst sense element(s)
are operating at the desired temperature.
a) Monitor EGO impedance feedback and verify
impedance ≤ 'EGO impedance active threshold';
this stage runs up to the maximum run time in the
'EGOZ Heater-Control Target Impedance /
Voltage Limit
Additional Wait Time'. If this check fails for any of
the pre-catalyst sensors the CL pre-cat test
status will indicate "Pre or Post-cat EGO Lazy"
and the appropriate EGO Lazy fault for the
sensor(s) is set.
b) In addition,
impedance
impedance is equal to the fully warm 'EGOZ
Impedance Target' + 'EGO Heater Impedance
Max Error'. If any EGO impedance fails to reach
the final target plus the impedance error
tolerance the heater power is deemed low, the
CL pre-cat test status "Pre-cat EGO Power Low"
is generated, and the appropriate EGO Lazy
fault for the sensor(s) is set. Once all pre-catalyst
EGOs have reached the active threshold
('Pre-cat EGO impedance active threshold) the
closed-loop system is activated and fueling
perturbation begins at the nominal fueling target
defined in the test setup parameters.
1-39
ECM SYSTEM
Schedule' + 'EGO
the system monitors
feedback and verifies
(To be continued)
KiSC issued 12, 2016 A
Heater
EGO
that