Dodge Viper SRT-10 (ZB). Manual — part 202
UPSTREAM OXYGEN SENSOR
The input from the upstream heated oxygen sensor
tells the PCM the oxygen content of the exhaust gas.
Based on this input, the PCM fine tunes the air-fuel
ratio by adjusting injector pulse width.
The sensor input switches from 0 to 1 volt, depend-
ing upon the oxygen content of the exhaust gas in
the exhaust manifold. When a large amount of oxy-
gen is present (caused by a lean air-fuel mixture), the
sensor produces voltage as low as 0.1 volt. When
there is a lesser amount of oxygen present (rich air-
fuel mixture) the sensor produces a voltage as high
as 1.0 volt. By monitoring the oxygen content and
converting it to electrical voltage, the sensor acts as
a rich-lean switch.
The heating element in the sensor provides heat to
the sensor ceramic element. Heating the sensor
allows the system to enter into closed loop operation
sooner.
In Closed Loop, the PCM adjusts injector pulse
width based on the upstream heated oxygen sensor
input along with other inputs. In Open Loop, the
PCM adjusts injector pulse width based on prepro-
grammed (fixed) values and inputs from other sen-
sors.
DOWNSTREAM OXYGEN SENSOR
The downstream heated oxygen sensor input is
used to detect catalytic convertor deterioration. As
the convertor deteriorates, the input from the down-
stream sensor begins to match the upstream sensor
input except for a slight time delay. By comparing
the downstream heated oxygen sensor input to the
input from the upstream sensor, the PCM calculates
catalytic convertor efficiency. Also used to establish
the upstream O2 goal voltage (switching point).
REMOVAL
8.3L - UPSTREAM 1/1, 2/1
(1) Raise and support vehicle.
(2) Disconnect heated oxygen sensor electrical con-
nector (Fig. 17).
(3) Remove sensor using an oxygen sensor crow
foot wrench such as Snap-On tool YA8875 or equiva-
lent
8.3L - DOWNSTREAM 1/2, 2/2
(1) Raise and support vehicle.
(2) Disconnect heated oxygen sensor electrical con-
nector (Fig. 17).
(3) Remove sensor using an oxygen sensor crow
foot wrench such as Snap-On tool YA8875 or equiva-
lent
INSTALLATION
8.3L - UPSTREAM 1/1, 2/1
(1) After removing the sensor, the exhaust mani-
fold threads must be cleaned with an 18 mm X 1.5 +
6E tap. If reusing the original sensor, coat the sensor
threads with an anti-seize compound such as Loctite
t
771- 64 or equivalent. New sensors have compound
on the threads and do not require an additional coat-
ing.
(2) Install sensor using an oxygen sensor crow foot
wrench such as Snap-On tool YA8875 or equivalent
(3) Tighten the sensor to 27 N·m (20 ft. lbs.)
torque.
(4) Plug sensor connector.
(5) Lower vehicle.
8.3L - DOWNSTREAM 1/2, 2/2
(1) After removing the sensor, the threads must be
cleaned with an 18 mm X 1.5 + 6E tap. If reusing the
original sensor, coat the sensor threads with an anti-
seize compound such as Loctite
t 771- 64 or equiva-
lent. New sensors have compound on the threads and
do not require an additional coating.
(2) Install sensor using an oxygen sensor crow foot
wrench such as Snap-On tool YA8875 or equivalent
(3) Tighten the sensor to 27 N·m (20 ft. lbs.)
torque.
(4) Plug sensor connector.
(5) Lower vehicle.
Fig. 17 2/1, 2/2, O2 SENSORS (Right Side)
1 - Upstream O2 Sensor
2 - Downstream O2 Sensor
14 - 38
FUEL INJECTION
ZB
O2 SENSOR (Continued)
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 intake man-
ifold 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 pintle
valve is used to supply air for above idle conditions.
The throttle position sensor (TPS) is attached to
the throttle body. The accelerator pedal cable is con-
nected to the throttle body linkage arm.
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
(1) Remove the battery cover and disconnect the
negative battery cable.
(2) Remove the air cleaner assembly, refer to the
Engine/Air Intake System/Air Cleaner Housing for
more information.
(3) Remove the throttle cable (Fig. 18).
(4) Disconnect the TPS electrical connector (Fig.
19).
(5) Remove the throttle body bolts (Fig. 20) and
wiring clips (Fig. 21).
(6) Remove the throttle body.
Fig. 18 THROTTLE CABLE AT THROTTLE BODY
Fig. 19 TPS & IDLE AIR CONTROL
1 - Throttle Position Sensor
2 - Idle Air Control Motor
3 - Fuel Rail
4 - Connector Fuel Line for Fuel Rails
Fig. 20 THROTTLE BODY
ZB
FUEL INJECTION
14 - 39
INSTALLATION
(1) Mount throttle body (Fig. 20) and wiring clips
(Fig. 21), tighten bolts to 12 N.m (105 in. lbs.).
(2) Connect electrical connector to throttle position
sensor (Fig. 19).
(3) Install the throttle cable (Fig. 18).
(4) Install the air cleaner housing, refer to Engine/
Air Intake System/Air Cleaner Housing.
(5) Connect the negative battery cable and install
the battery cover.
THROTTLE CABLE
REMOVAL
(1) Disconnect cable from throttle cam (Fig. 22).
(2) From inside the vehicle, hold the accelerator
pedal up and remove the cable retainer and throttle
cable from pedal (Fig. 23).
(3) Squeeze the tabs on the retainer at the dash
panel. Push the retainer out of the dash panel.
Remove the cable assembly (Fig. 24).
Fig. 21 WIRING CLIP
Fig. 22 THROTTLE CABLE AT THROTTLE BODY
Fig. 23 THROTTLE CABLE AT ACCELERATOR
PEDAL
14 - 40
FUEL INJECTION
ZB
THROTTLE BODY (Continued)
INSTALLATION
(1) Insert cable assembly through opening in dash
panel (Fig. 24). Seat cable retainer in dash panel.
(2) From inside the vehicle, hold up the pedal and
install the throttle cable and cable retainer in the
upper end of the pedal shaft (Fig. 23).
(3) Connect the throttle cable to the throttle body
(Fig. 22).
THROTTLE POSITION SENSOR
DESCRIPTION
The TPS is mounted on the passenger side of the
throttle body. The sensor connects to the throttle
blade shaft (Fig. 25). The TPS is a variable resistor
that provides the Powertrain Control Module (PCM)
with an input signal (voltage).
OPERATION
The TPS is a variable resistor that provides the
PCM with an input signal (voltage). The signal rep-
resents throttle blade position. As the position of the
throttle blade changes, the resistance of the TPS
changes.
The PCM supplies approximately 5 volts to the
TPS. The TPS output voltage (input signal to the
PCM) represents throttle blade position. The TPS
output voltage to the PCM varies from approximately
0.5 volt at minimum throttle opening (idle) to 3.5
volts at wide open throttle. Along with inputs from
other sensors, the PCM uses the TPS input to deter-
mine current engine operating conditions. The PCM
also adjusts fuel injector pulse width and ignition
timing based on these inputs.
REMOVAL
The TPS is attached to the throttle body (Fig. 25).
(1) Disconnect the TPS electrical connector.
(2) Remove the TPS mounting screws.
(3) Remove the TPS.
Fig. 24 THROTTLE CABLE ROUTING
Fig. 25 TPS & IDLE AIR CONTROL
1 - Throttle Position Sensor
2 - Idle Air Control Motor
3 - Fuel Rail
4 - Connector Fuel Line for Fuel Rails
ZB
FUEL INJECTION
14 - 41
THROTTLE CABLE (Continued)
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