ECM SYSTEM
WG1605-G-E3,WG1605-L-E3,WG1605-GL-E3, DM
1-52
HEATED EXHAUST GAS OXYGEN SENSOR (HEGO)
(ALL)
The Heated Exhaust Gas Oxygen Sensor (HEGO) is
mounted in the exhaust system, downstream of the
engine, but before the catalyst, referred to as the "Pre
Catalyst" sensor. The ECM continuously monitors the
HEGO sensor output if a rich or lean condition is present
for an extended period of time, and if the ECM cannot
correct the condition, the ECM will set a diagnostic code,
and turn on the MIL light in the dash.
The HEGO is used to measure the amount of
oxygen, present in the exhaust stream, and
communicate that to the ECM, via an electrical signal.
The amount of oxygen, present in the exhaust stream,
indicates whether the fuel air ratio is too rich or too lean.
If the HEGO sensor signal indicates that the exhaust
stream is too rich, the ECM will decrease or lean the fuel
mixture, during engine operation. If the mixture is too
lean, the ECM will richen the mixture.
When the air/fuel mixture is rich, and there is little
oxygen in the exhaust, the difference in oxygen levels,
across the sensing element, generates a voltage
through the sensor's electrodes: typically 0.800 to
0.900 V. When the air/fuel mixture is lean and there is
more oxygen in the exhaust, the sensor's voltage drops
to 0.100 to 0.300 V. When the air/fuel mixture is perfectly
balanced and combustion is cleanest, the sensor's
output voltage is around 0.450 V.
The oxygen sensor's voltage signal is monitored by
the EControls ECM, to regulate the fuel mixture. When
the ECM sees a rich signal (high voltage), from the O
2
sensor, it commands the fuel mixture to go lean. When
the computer receives a lean signal (low voltage) from
the O
2
sensor, it commands the fuel mixture to go rich.
The continued cycling, back and forth from rich to lean,
averages out the overall air/fuel mixture, to minimize
emissions, and to help the catalytic converter operate at
peak efficiency, which is often referred to as the "duty
cycle".
The speed with which the oxygen sensor reacts to
oxygen changes in the exhaust is very important for
accurate fuel control, peak fuel economy, and low
emissions. Aging of the sensor due to exposure to
contaminants in the fuel, will occur over time, and may
cause the sensor to slow down.
On all USA Emission certified engines, the exhaust
system is attached with a second HEGO, located after
the catalyst, referred to as the "Post Catalyst" sensor.
The function of the second HEGO is to monitor the
efficiency of the catalyst and fuel control. The operation
of the HEGO is the same as the Pre Catalyst sensor; it
provides an output voltage to the ECM, to determine the
level of oxygen, in the exhaust stream after the catalyst.
This type of monitoring is referred to as the On Board
Diagnostic, in which additional sensors are installed in
the system, to monitor the fuel control systems.
The ECM continuously monitors the HEGO sensors
output, if a rich or lean condition is present for an
extended period of time and the ECM cannot correct the
condition, the ECM will set a diagnostic code and turn on
the MIL light in the dash.
Figure 18:
Heated Exhaust Gas Oxygen Sensor
(HEGO)
FUEL SYSTEM SELECT SWITCH (GL, GLN)
As explained earlier, there are two complete fuel
systems, included in Kubota bi-fuel system. To
adequately protect the engine from damage caused by
introducing two fuels simultaneously, the Kubota has
designed a Fuel System Select switch which signals the
ECM to change fuels. The switch is typically either a two
position, or three positioned switch. When using a three
position switch in the center position neither the gasoline
fuel pump nor the electric lock off, can be energized.
Rotating the switch in one direction or the other will
activate the fuel system, the operator has chosen.
CAUTION
The Heated Exhaust Gas Oxygen Sensor is an emissions control
component. If the HEGO fails to operate, replace only with Kubota
replacement part. The HEGO sensor is sensitive to silicone based
products and can become contaminated. Avoid using silicone
sealers or hoses, treated with silicone lubricant, in the air stream or
fuel supply lines.
KiSC issued 12, 2016 A
Summary of Contents for WG1605-E3
Page 1: ...WG1605 E3 DIAGNOSIS MANUAL ECM SYSTEM KiSC issued 12 2016 A...
Page 3: ...I INFORMATION KiSC issued 12 2016 A...
Page 4: ...CONTENTS 1 SAFETY FIRST I 1 INFORMATION KiSC issued 12 2016 A...
Page 8: ...1 ECM SYSTEM KiSC issued 12 2016 A...
Page 10: ...23 Spark Coil Primary DTC 2300 2301 2303 2304 2306 2307 2309 2310 1 228 KiSC issued 12 2016 A...
