Dodge RAM 1500 1998 Owner's Manual page 1604

DR
MAP SENSOR (Continued)
(4) Install MAP sensor mounting bolts (screws).
Refer to Torque Specifications.
(5) Connect electrical connector.
5.7L V-8
The Manifold Absolute Pressure (MAP) sensor is
mounted to the front of the intake manifold air ple-
num box (Fig. 24).
(1) Clean MAP sensor mounting hole at intake
manifold.
(2) Check MAP sensor o-ring seal for cuts or tears.
(3) Position sensor into manifold.
(4) Rotate sensor 1/4 turn clockwise for installa-
tion.
(5) Connect electrical connector.
OXYGEN SENSOR
DESCRIPTION
The Oxygen Sensors (O2S) are attached to, and
protrude into the vehicle exhaust system. Depending
on the engine or emission package, the vehicle may
use a total of either 2 or 4 sensors.
Federal Emission Packages : Two sensors are
used: upstream (referred to as 1/1) and downstream
(referred to as 1/2). With this emission package, the
upstream sensor (1/1) is located just before the main
catalytic convertor. The downstream sensor (1/2) is
located just after the main catalytic convertor.
California Emission Packages: On this emis-
sions package, 4 sensors are used: 2 upstream
(referred to as 1/1 and 2/1) and 2 downstream
(referred to as 1/2 and 2/2). With this emission pack-
age, the right upstream sensor (2/1) is located in the
right exhaust downpipe just before the mini-catalytic
convertor. The left upstream sensor (1/1) is located in
the left exhaust downpipe just before the mini-cata-
lytic convertor. The right downstream sensor (2/2) is
located in the right exhaust downpipe just after the
mini-catalytic convertor, and before the main cata-
lytic convertor. The left downstream sensor (1/2) is
located in the left exhaust downpipe just after the
mini-catalytic convertor, and before the main cata-
lytic convertor.
REMOVAL
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. 26) or (Fig. 27) for typical O2S (oxy-
gen sensor) locations.
FUEL INJECTION - GAS
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 tap.
Fig. 26 O2 SENSOR SYSTEM - WITH 4 SENSORS
Fig. 27 O2 SENSOR SYSTEM - WITH 2 SENSORS
1 - POST CATALYST OXYGEN SENSOR (1/3)
2 - PRE-CATALYST OXYGEN SENSOR (1/2)
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