Restricted Exhaust System Diagnosis; Exhaust System Description; Check At Heated Exhaust Gas Oxygen Sensor - Kubota WG1605-E3 Diagnostic Manual

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

(1) Restricted Exhaust System Diagnosis

Exhaust System Description

The emission certified engine has been designed
and calibrated to meet the emission standards in effect
for 2010. To help meet the emission requirements the
vehicle has been attached with a three way catalyst. The
catalyst is a three way catalyst, sound damping and
spark arresting unit. Besides controlling the noise
created from the combustion process, and preventing
sparks from escaping from the exhaust system the most
important function is treating the exhaust gases which
are created from the combustion process. The three-way
catalyst consists of a honeycomb core coated with a
mixture of precious metals. The hot gases flow through
the catalyst honeycomb core where an oxidation and
reduction reactions take
reactions reduce the amount of CO, HC and NOX in the
engines exhaust. The Exhaust gas then flows through
the tailpipe outlet.
During normal operation the exhaust system could
become damaged. Damage which reduces the flow of
the exhaust gas will create increased back pressure in
the engine. Reduction in exhaust flow can result from
crushed muffler outlets or melted catalyst brick inside the
converter.
It may be necessary to measure the back pressure
in the exhaust system. To determine if the back pressure
in the engine is correct use the following procedure.
Diagnostic Aids
Tools Required:
• Back pressure gage 0 to 69 kPa (0 to 0.70 kgf/cm
0 to 10 psi)
Diagnostic Scan Tool:
• EControls GCP Display SW Tool
place. These chemical
2
,
1-101

Check at Heated Exhaust Gas Oxygen Sensor

(HEGO)
1. Carefully remove the HEGO.
2. Install exhaust back pressure gage in place of the
HEGO Refer to Figure 1.
3. With the engine idling at normal operating
temperature, observe the exhaust system back
pressure reading on the gage. Reading should not
exceed 8.6 kPa (0.088 kgf/cm
4. Increase engine speed to 2000 RPM and observe
gage. Reading should not exceed 20.7 kPa
2
(0.21 kgf/cm , 3 psi).
5. If the back pressure at either speed exceeds
specification, a restricted exhaust system is
indicated.
6. Inspect the entire exhaust system for a collapsed
pipe, heat distress or possible internal muffler failure.
7. If there are no obvious reasons for the excessive
back pressure, the catalytic converter is suspected
to be restricted and should be replaced using the
recommended procedures.
(1) Back Pressure Gage
(2) Oxygen Sensor (O S)
2
ECM SYSTEM
2
, 1.25 psi).
(3) Exhaust Manifold
KiSC issued 12, 2016 A