2007 ISUZU KB P190 catalytic converter

6E–52 ENGINE DRIVEABILITY AND EMISSIONS
GENERAL DESCRIPTION FOR FUEL
METERING
The fuel metering system starts with the fuel in the fuel
tank. An electric fuel pump, located in the fuel tank,
pumps fuel to the fuel rail through an in-line fuel filter.
The pump is designed to provide fuel at a pressure
above the pressure needed by the injectors.
A fuel pressure regulator in the fuel rail keeps fuel
available to the fuel injectors at a constant pressure.
A return line delivers unused fuel back to the fuel tank.
The basic function of the air/fuel metering system is to
control the air/fuel delivery to the engine. Fuel is
delivered to the engine by individual fuel injectors
mounted in the intake manifold.
The main control sensor is the heated oxygen sensor
located in the exhaust system. The heated oxygen
sensor reports to the ECM how much oxygen is in the
exhaust gas. The ECM changes the air/fuel ratio to the
engine by controlling the amount of time that fuel
injector is “On”.
The best mixture to minimize exhaust emissions is 14.7
parts of air to 1 part of gasoline by weight, which allows
the catalytic converter to operate most efficiently.
Because of the constant measuring and adjusting of the
air/fuel ratio, the fuel injection system is called a “closed
loop” system.
The ECM monitors signals from several sensors in
order to determine the fuel needs of the engine. Fuel is
delivered under one of several conditions called “mode”.
All modes are controlled by the ECM.
Battery Voltage Correction Mode
When battery voltage is low, the ECM will compensate
for the weak spark by increasing the following:
• The amount of fuel delivered.
• The idle RPM.
Clear Flood Mode
Clear a flooded engine by pushing the accelerator pedal
down all the way. The ECM then de-energizes the fuel
injectors. The ECM holds the fuel injectors de-energized
as long as the throttle remains above 75% and the
engine speed is below 800 RPM. If the throttle position
becomes less than 75%, the ECM again begins to pulse
the injectors ON and OFF, allowing fuel into the
cylinders.
Deceleration Fuel Cutoff (DFCO) Mode
The ECM reduces the amount of fuel injected when it
detects a decrease in the throttle position and the air
flow. When deceleration is very fast, the ECM may cut
off fuel completely. Until enable conditions meet the
engine revolution less 1000 rpm or manifold absolute
pressure less than 10 kPa.
Engine Speed/ Vehicle Speed/ Fuel Disable
Mode
The ECM monitors engine speed. It turns off the fuel
injectors when the engine speed increases above 6000
RPM. The fuel injectors are turned back on when
engine speed decreases below 3500 RPM.
Acceleration Mode
The ECM provides extra fuel when it detects a rapid
increase in the throttle position and the air flow.
Fuel Cutoff Mode
No fuel is delivered by the fuel injectors when the
ignition is OFF. This prevents engine run-on. In addition,
the ECM suspends fuel delivery if no reference pulses
are detected (engine not running) to prevent engine
flooding.
Starting Mode
When the ignition is first turned ON, the ECM energizes
the fuel pump relay for two seconds to allow the fuel
pump to build up pressure. The ECM then checks the
engine coolant temperature (ECT) sensor and the
throttle position sensor to determine the proper air/fuel
ratio for starting.
The ECM controls the amount of fuel delivered in the
starting mode by adjusting how long the fuel injectors
are energized by pulsing the injectors for very short
times.
Run Mode
The run mode has the following two conditions:
• Open loop
• Closed loop
When the engine is first started, the system is in “open
loop” operation. In “Open Loop,” the ECM ignores the
signal from the heated oxygen sensor (HO2S). It
calculates the air/fuel ratio based on inputs from the TP,
ECT, and MAP sensors.
The system remains in “Open Loop” until the following
conditions are met:
• The HO2S has a varying voltage output showing that it is hot enough to operate properly (this depends on
temperature).
• The ECT has reached a specified temperature.
• A specific amount of time has elapsed since starting the engine.
• Engine speed has been greater than a specified RPM since start-up.
The specific values for the above conditions vary with
different engines and are stored in the programmable
read only memory (PROM). When these conditions are
met, the system enters “closed loop” operation. In
“closed loop,” the ECM calculates the air/fuel ratio
(injector on-time) based on the signal from the HO2S.
This allows the air/fuel ratio to stay very close to 14.7:1.

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ISUZU KB P190 2007

6E–258 ENGINE DRIVEABILITY AND EMISSIONS
EXCESSIVE EXHAUST EMISSIONS OR ODORS SYMPTOM
DEFINITIONS: Vehicle fails an emission test. There is excessive “rotten egg” smell. (Excessive odors do not
necessarily indicate excessive emissions.)
Step Action Value(s) Yes No
1 Was the “ On-Board Diagnostic (OBD) System Check ”
performed? — Go to Step 2Go to
OBD
System Check
2 1. Perform a bulletin search. 2. If a bulletin that addresses the symptom is found,correct the condition as instructed in the bulletin.
Was a bulletin found that addresses the symptom? — Verify repair Go to Step 3
3 Was a visual/physical check performed? —Go to Step 4Go to
Visual /
physical Check .
4 Does the customer continual accelerate On/Off during cold condition? — System OK Go to Step 5
5 Is the customer using the incorrect fuel type? —Replace with
unleaded fuel Go to Step 6
6 Check for vacuum leaks (vacuum lines, intake manifold, throttle body, etc.)
Were any vacuum leaks found? — Go to Step 17Go to Step 7
7 1. Check fuel cap for proper installation. 2. Secure the fuel cap if necessary.
Was a problem found? — Go to Step 17Go to Step 8
8 Check the fuel pressure. Refer to 6E-108 page “Fuel
System Diagnosis” .
Was a problem found? — Go to Step 17Go to Step 9
9 1. Check for faulty, plugged or incorrectly installed PCV valve.
2. Verify that the PCV system is not plugged.
Was a problem found? — Go to Step 17Go to Step 10
10 Check the injector connectors, if any of the injectors are connected to an incorrect cylinder, correct as
necessary.
Was a problem found? — Go to Step 17Go to Step 11
11 Perform the “Injector Coil/Balance Test
” (Refer to 6E-
98 page).
Was a problem found. — Go to Step 17Go to Step 12
12 Check for a problem with the engine cooling system. Was a problem found? — Go to Step 17Go to Step 13
13 Check EVAP canister for fuel loading. Refer to Evaporative Emission Control System.
Was a problem found? — Go to Step 17Go to Step 14
14 Check the EVAP purge solenoid valve operation. Is the valve operated normally? — Go to Step 17Verify repair &
Go to Step 15
15 Check the exhaust system for a possible restriction: • Damaged or collapsed pipes
• Internal catalytic converter failure
Was a problem found? —Verify repair &
Go to Step 16 Go to Step 17

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ISUZU KB P190 2007

ENGINE EXHAUST 6F-1
SECTION 6F
ENGINE EXHAUST
TABLE OF CONTENTS
PAGE
General Description ....................................................................................................... 6F- 2
Service Precaution ......................................................................................................... 6F- 4
Exhaust Pipe ................................................................................................................... 6F- 5
Exhaust pipe and Associated parts ......................................................................... 6F- 5
Removal ...................................................................................................................... 6F- 5
Installation .................................................................................................................. 6F- 6
Inspection ................................................................................................................... 6F- 6
Front Exhaust Pipe ......................................................................................................... 6F- 7
Front Exhaust Pipe and Associated Parts ............................................................... 6F- 7
Removal ...................................................................................................................... 6F- 7
Installation .................................................................................................................. 6F- 7
Mid Pipe....................................................................................................................... .... 6F- 8
Mid Pipe and associated Parts ................................................................................. 6F- 8
Removal ...................................................................................................................... 6F- 8
Installation .................................................................................................................. 6F- 8
Catalytic Converter (If applicable)................................................................................. 6F- 9 Catalytic Converter and Associated Parts ............................................................... 6F- 9
Removal ...................................................................................................................... 6F- 9
Installation .................................................................................................................. 6F- 9
3 way Catalytic Converter System............................................................................ 6F- 10
Exhaust Silencer ............................................................................................................ 6F- 12
Exhaust Silencer and Associated Parts .................................................................. 6F- 12
Removal ...................................................................................................................... 6F- 12
Installation .................................................................................................................. 6F- 13
Main Data and Specifications ........................................................................................ 6F- 14
Torque Specification ................................................................................................. 6F- 15


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ISUZU KB P190 2007

ENGINE EXHAUST 6F-3





























W hen inspecting or replacing exhaust system components,
make sure there is adequate clearance from all points on the
underbody to prevent overheating the floor pan and possible
damage to the passenger compartment insulation and trim
materials.
Check complete exhaust system and nearby body areas and
rear compartment lid for broken, damaged, missing or
mispositioned parts, open seams, holes, loose connections or
other deterioration which could permit exhaust fumes to seep
into the rear compartment or passenger compartment. Dust or
water in the rear compartment may be an indication of a
problem in one of these areas. Any faulty areas should be
corrected immediately.
Hangers
Various types of hangers are used to support exhaust
system(s). These include conventional rubber straps, rubber
rings, and rubber blocks.
The installation of exhaust system supports is very important,
as improperly installed supports can cause annoying vibrations
which can be difficult to diagnose.
Three Way Catalytic Converter (If applicable)
The three way catalytic converter is an emission control device
added to the exhaust system to reduce pollutants from the
exhaust gas stream.

CAUTION: The catalytic converter requires the use of
unleaded fuel only.
Periodic maintenance of the exhaust system is not required. If
the vehicle is raised for other service, it is advisable to check
the condition of the complete exhaust system.
A dual bed monolith catalytic converter is used in combination
with three way catalytic converter.
Catalytic Types:
Three way (Reduction/Oxidation) catalyst
The catalyst coating on the three way (reduction) converter
contains platinum and rhodium which lowers the levels of
nitrous oxide (NOx) as well as hydrocarbons (HC) and carbon
monoxide (Co).
Gasket
The gasket must be replaced whenever a new exhaust pipe,
muffler or catalytic converter is installed.

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ISUZU KB P190 2007

ENGINE EXHAUST 6F-5
Exhaust Pipe
Exhaust Pipe and Associated parts




RTW 46FLF000401













Removal
(2.4L)
CAUTION
When you remove or install the front exhaust pipe, make
sure not to damage the fuel evaporative pipe.
1. Damper rubber
2. Exhaust silencer
3. Mid pipe
4. Damper rubber
5. Front exhaust pipe fixing nut
6. Catalytic converter (If applicable)
7. Front exhaust pipe

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ISUZU KB P190 2007

6F-6 ENGINE EXHAUST


Installation
To install, follow the removal steps in the reverse order.










Important - Installation
1. Front Exhaust Pipe Flange Nut
Connect the exhaust pipe to the exhaust manifold.
Front exhaust pipe to manifold nut.
Torque
N⋅m (kgf ⋅m)
28 (2.9)
Inspection
Make the necessary adjustments, and part replacements if
excessive wear or damage is discover during inspection.

1. Front Exhaust Pipe
2. Center Exhaust Pipe and Catalytic Converter Flange Nut
3. Exhaust Pipe Damper Rubber
4. Exhaust Silencer with Rear Exhaust Pipe

Check the pipes for for corrosion, cracking , damage or
misalignment and repair if required.
Check the damper rubber for deterioration or damage and
repair if required.

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ISUZU KB P190 2007

ENGINE EXHAUST 6F-7
Front Exhaust Pipe (W/O Catalytic
Converter)
Front Exhaust Pipe and Associated Parts




RTW 46F000101
Legend
1. Front Exhaust Pipe Fixing Nuts
2. Front Exhaust Pipe
3. Mid Exhaust Pipe Fixing Nuts











Removal
(2.4L)
1. Disconnect battery ground cable.
2. Raise the vehicle and support with suitable safety stands.
3. Remove the front exhaust pipe fixing nuts (1).
4. Remove mid pipe fixing nuts (3).
5. Remove front exhaust pipe (2).




Installation
1. Install front exhaust pipe (2) and tighten four nuts (1). Torque:
Nuts: 28 N ⋅
⋅⋅
⋅
m (2.9 kgf ⋅
⋅⋅
⋅
m)
2. Tighten two nuts (3). Torque: 43 N ⋅
⋅⋅
⋅
m (4.4 kgf ⋅
⋅⋅
⋅
m)


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ISUZU KB P190 2007

ENGINE EXHAUST 6F-9
Catalytic Converter (If applicable)
Catalytic Converter and Associated Parts



RTW 46FSF000301
Legend
1. Catalytic Converter
2. O
2 Sensor Converter
3. Front Pipe Fixing Nuts
4. Mid Pipe Fixing Nuts









Removal
(2.4L)
1. Disconnect battery ground cable.
2. Raise the vehicle and support with suitable safety stands.
3. Remove front pipe fixing nuts (3).
4. Remove mid pipe fixing nuts (4).
5. Remove the O
2 sensor connector (2).
6. Remove the front exhaust pipe with catalytic converter (1).





Installation
1. Install Catalytic Converter (1) and tighten four to the specified torque:
Torque:
Fixing nuts: 28 N ⋅
⋅⋅
⋅
m (2.9 kgf ⋅
⋅⋅
⋅
m)
2. Tight two nuts (4) Torque:
Nuts: 43 N ⋅
⋅⋅
⋅
m (4.4 kgf ⋅
⋅⋅
⋅
m)
3. Connect the O
2 sensor connector (2).


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ISUZU KB P190 2007