Jeep Wrangler TJ. Manual — part 469
ratio until the upstream sensor inputs a voltage that
the PCM has determined will make the downstream
sensor output (oxygen content) correct.
The upstream oxygen sensor also provides an input
to determine catalytic convertor efficiency.
Downstream Sensor - Engine Equipped With
2 Sensors: The downstream oxygen sensor (1/2) is
also used to determine the correct air-fuel ratio. As
the oxygen content changes at the downstream sen-
sor, the PCM calculates how much air-fuel ratio
change is required. The PCM then looks at the
upstream oxygen sensor voltage and changes fuel
delivery until the upstream sensor voltage changes
enough to correct the downstream sensor voltage
(oxygen content).
The downstream oxygen sensor also provides an
input to determine catalytic convertor efficiency.
Upstream Sensors - Engine Equipped With 4
Sensors: Two upstream sensors are used (1/1 and
2/1). The 1/1 sensor is the first sensor to receive
exhaust gases from the #1 cylinder. They provide an
input voltage to the PCM. The input tells the PCM
the oxygen content of the exhaust gas. The PCM uses
this information to fine tune fuel delivery to main-
tain the correct oxygen content at the downstream
oxygen sensors. The PCM will change the air/fuel
ratio until the upstream sensors input a voltage that
the PCM has determined will make the downstream
sensors output (oxygen content) correct.
The upstream oxygen sensors also provide an input
to determine mini-catalyst efficiency. Main catalytic
convertor efficiency is not calculated with this pack-
age.
Downstream Sensors - Engine Equipped With
4 Sensors: Two downstream sensors are used (1/2
and 2/2). The downstream sensors are used to deter-
mine the correct air-fuel ratio. As the oxygen content
changes at the downstream sensor, the PCM calcu-
lates how much air-fuel ratio change is required. The
PCM then looks at the upstream oxygen sensor volt-
age, and changes fuel delivery until the upstream
sensor voltage changes enough to correct the down-
stream sensor voltage (oxygen content).
The downstream oxygen sensors also provide an
input to determine mini-catalyst efficiency. Main cat-
alytic convertor efficiency is not calculated with this
package.
Engines equipped with either a downstream sen-
sor(s), or a post-catalytic sensor, will monitor cata-
lytic
convertor
efficiency.
If
efficiency
is
below
emission standards, the Malfunction Indicator Lamp
(MIL) will be illuminated and a Diagnostic Trouble
Code (DTC) will be set. Refer to Monitored Systems
in Emission Control Systems for additional informa-
tion.
REMOVAL
2.4L
CAUTION: Never apply any type of grease to the
oxygen sensor electrical connector, or attempt any
soldering of the sensor wiring harness.
Refer to (Fig. 22) for O2S (oxygen sensor) location.
WARNING: THE EXHAUST MANIFOLD, EXHAUST
PIPES
AND
CATALYTIC
CONVERTER
BECOME
VERY HOT DURING ENGINE OPERATION. ALLOW
ENGINE TO COOL BEFORE REMOVING OXYGEN
SENSOR.
(1) Raise and support vehicle.
(2) Disconnect wire connector from O2S sensor.
CAUTION: When disconnecting sensor electrical
connector, do not pull directly on wire going into
sensor.
(3) Remove O2S sensor with an oxygen sensor
removal and installation tool.
(4) Clean threads in exhaust pipe using appropri-
ate size tap.
Fig. 22 OXYGEN SENSORS - 2.4L
1 - ELECTRICAL CONNECTORS
2 - UPSTREAM SENSOR (1/1)
3 - ELECTRICAL CONNECTORS
4 - DOWNSTREAM SENSOR (1/2)
TJ
FUEL INJECTION
14 - 35
O2 SENSOR (Continued)
4.0L
CAUTION: Never apply any type of grease to the
oxygen sensor electrical connector, or attempt any
soldering of the sensor wiring harness.
Refer to (Fig. 23), (Fig. 24) for O2S (oxygen sensor)
location.
WARNING: THE EXHAUST MANIFOLD, EXHAUST
PIPES
AND
CATALYTIC
CONVERTER
BECOME
VERY HOT DURING ENGINE OPERATION. ALLOW
ENGINE TO COOL BEFORE REMOVING OXYGEN
SENSOR.
(1) Raise and support vehicle.
(2) Disconnect wire connector from O2S sensor.
CAUTION: When disconnecting sensor electrical
connector, do not pull directly on wire going into
sensor.
(3) Remove O2S sensor with an oxygen sensor
removal and installation tool.
(4) Clean threads in exhaust pipe using appropri-
ate size tap.
INSTALLATION
Threads of new oxygen sensors are factory coated
with anti-seize compound to aid in removal. DO
NOT add any additional anti-seize compound to
the threads of a new oxygen sensor.
(1) Install O2S sensor. Tighten to 30 N·m (22 ft.
lbs.) torque.
(2) Connect O2S sensor wire connector.
(3) Lower vehicle.
THROTTLE BODY
DESCRIPTION
The throttle body is located on the intake manifold.
Fuel does not enter the intake manifold through the
throttle body. Fuel is sprayed into the manifold by
the fuel injectors.
OPERATION
Filtered air from the air cleaner enters the intake
manifold through the throttle body. The throttle body
contains an air control passage controlled by an Idle
Air Control (IAC) motor. The air control passage is
used to supply air for idle conditions. A throttle valve
(plate) is used to supply air for above idle conditions.
Certain sensors are attached to the throttle body.
The accelerator pedal cable, speed control cable and
transmission control cable (when equipped) are con-
nected to the throttle body linkage arm.
Fig. 23 OXYGEN SENSORS - 4.0L - FEDERAL
EMISSIONS
1 - 1/2 O2S
2 - 1/1 02S
Fig. 24 OXYGEN SENSORS - 4.0L - CALIFORNIA
EMISSIONS
1 - 1/2 O2S
2 - 1/1 O2S
3 - 2/1 O2S
4 - 2/2 O2S
14 - 36
FUEL INJECTION
TJ
O2 SENSOR (Continued)
A (factory adjusted) set screw is used to mechani-
cally limit the position of the throttle body throttle
plate. Never attempt to adjust the engine idle
speed using this screw. All idle speed functions are
controlled by the PCM.
REMOVAL
2.4L
A (factory adjusted) set screw is used to mechani-
cally limit the position of the throttle body throttle
plate. Never attempt to adjust the engine idle
speed using this screw. All idle speed functions are
controlled by the Powertrain Control Module (PCM).
(1) Remove air cleaner tube at throttle body.
(2) Disconnect throttle body electrical connectors
at IAC motor and TPS.
(3) Remove all control cables from throttle body
(lever) arm. Refer to the Accelerator Pedal and Throt-
tle Cable section for removal/installation procedures.
(4) Disconnect necessary vacuum lines at throttle
body.
(5) Remove 3 throttle body mounting bolts (Fig.
25).
(6) Remove throttle body from intake manifold.
(7) Check condition of old throttle body-to-intake
manifold o-ring.
4.0L
A (factory adjusted) set screw is used to mechani-
cally limit the position of the throttle body throttle
plate. Never attempt to adjust the engine idle
speed using this screw. All idle speed functions are
controlled by the Powertrain Control Module (PCM).
(1) Remove air cleaner tube at throttle body.
(2) Disconnect throttle body electrical connectors
at MAP sensor, IAC motor and TPS (Fig. 26).
(3) Remove all control cables from throttle body
(lever) arm. Refer to the Accelerator Pedal and Throt-
tle Cable section of this group for additional informa-
tion.
(4) Remove four throttle body mounting bolts.
(5) Remove throttle body from intake manifold.
(6) Discard old throttle body-to-intake manifold
gasket.
INSTALLATION
2.4L
(1) Check condition of throttle body-to-intake man-
ifold o-ring. Replace as necessary.
(2) Clean mating surfaces of throttle body and
intake manifold.
(3) Install throttle body-to-intake manifold o-ring.
(4) Install throttle body to intake manifold.
(5) Install 3 mounting bolts. Tighten bolts to 12
N·m (105 in. lbs.) torque.
Fig. 25 THROTTLE BODY MOUNTING BOLTS - 2.4L
1 - THROTTLE BODY
2 - IGNITION COIL
3 - MOUNTING BOLTS (3)
Fig. 26 THROTTLE BODY AND SENSOR
LOCATIONS - 4.0L
1 - MOUNTING BOLTS (4)
2 - THROTTLE BODY
3 - IAC MOTOR
4 - ELEC. CONN.
5 - TPS
6 - MAP SENSOR
7 - ELEC. CONN.
8 - IAT SENSOR
9 - ELEC. CONN.
TJ
FUEL INJECTION
14 - 37
THROTTLE BODY (Continued)
(6) Install control cables.
(7) Install electrical connectors.
(8) Install necessary vacuum lines.
(9) Install air cleaner duct at throttle body.
4.0L
A (factory adjusted) set screw is used to mechani-
cally limit the position of the throttle body throttle
plate. Never attempt to adjust the engine idle
speed using this screw. All idle speed functions are
controlled by the Powertrain Control Module (PCM).
(1) Clean mating surfaces of throttle body and
intake manifold.
(2) Install new throttle body-to-intake manifold
gasket.
(3) Install throttle body to intake manifold.
(4) Install four mounting bolts. Tighten bolts to 11
N·m (100 in. lbs.) torque.
(5) Install control cables.
(6) Install electrical connectors.
(7) Install air cleaner at throttle body.
THROTTLE CONTROL CABLE
REMOVAL
2.4L
CAUTION: Be careful not to damage or kink the
cable core wire (within the cable sheathing) while
servicing accelerator pedal or throttle cable.
(1) From inside vehicle, hold up accelerator pedal.
Remove plastic cable retainer (clip) and throttle cable
core wire from upper end of pedal arm (Fig. 27).
Plastic cable retainer snaps into top of pedal arm.
(2) Remove cable core wire at pedal arm.
(3) From inside vehicle, pinch both sides of cable
housing retainer tabs (Fig. 27) at dash panel.
Remove cable housing from dash panel and pull into
engine compartment.
(4) Remove air box at throttle body.
(5) Unsnap cable from dashpanel routing clip.
(6) Remove cable housing from dash panel and
pull into engine compartment.
(7) Hold throttle in wide open position. While held
in this position, slide throttle cable pin (Fig. 28) from
throttle body bellcrank.
(8) Using a pick or small screwdriver, press release
tab (Fig. 28) to release plastic cable mount from
bracket. Press on tab only enough to release
cable from bracket. If tab is pressed too much,
it will be broken.To remove throttle cable from
throttle body bracket, slide cable towards front of
vehicle.
(9) Remove throttle cable from vehicle.
Fig. 27 ACCELERATOR PEDAL MOUNTING
1 - CABLE RETAINER
2 - SLOT
3 - MOUNTING STUDS (2)
4 - PEDAL/BRACKET ASSEMBLY
5 - MOUNTING STUDS
6 - RETAINER TABS
7 - CABLE
8 - CABLE STOP
Fig. 28 THROTTLE CABLE, PIN, RELEASE TAB -
2.4L
1 - MOUNTING BRACKET
2 - SPEED CONTROL CABLE
3 - THROTTLE CABLE
4 - RELEASE TAB
5 - CABLE PINS
6 - BELLCRANK
14 - 38
FUEL INJECTION
TJ
THROTTLE BODY (Continued)
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