1999 DODGE NEON engine

VISUAL INSPECTIONÐDOHC
Before diagnosing or servicing the fuel injection
system, perform a visual inspection for loose, discon-
nected, or misrouted wires and hoses (Fig. 53). Athorough visual inspection that includes the following
checks saves unnecessary test and diagnostic time.
(1) Inspect the battery connections. Clean corroded
terminals (Fig. 31).
(2) Check the 2 PCM 40-way connector for
stretched wires on pushed out terminals (Fig. 54).
Fig. 49 Upstream Heated Oxygen Sensor
Fig. 50 Downstream Heated Oxygen Sensor
Fig. 51 Fuel Pump Module Electrical Connector
Fig. 52 Battery Temp. Sensor Connectors
Fig. 53 2.0L DOHC Engine Compartment
14 - 40 FUEL SYSTEMPL
DIAGNOSIS AND TESTING (Continued)

(13) Inspect the air cleaner filter element. Replace
as necessary. Check the air induction system for
restrictions.
(14) Check the electrical connection at the knock
sensor (Fig. 64).
(15) Check the electrical connections at the cam-
shaft position sensor (Fig. 65) and engine coolant
temperature sensor (Fig. 66).
(16) Check the electrical connector at the Elec-
tronic EGR Transducer. Inspect the vacuum and back
pressure hoses at the solenoid and transducer for
leaks (Fig. 67).
(17) Inspect the electrical connections at the gen-
erator (Fig. 68). Check the generator belt for glazing
or damage.
Fig. 63 Starter Motor and Ground Strap
Fig. 64 Knock Sensor
Fig. 65 Camshaft Position Sensor
Fig. 66 Engine Coolant Temperature Sensor
Fig. 67 Electronic EGR Transducer
PLFUEL SYSTEM 14 - 43
DIAGNOSIS AND TESTING (Continued)

(7) Attach the other end of the jumper wire to
relay terminal 86. This activates the relay. The ohm-
meter should now show continuity between relay ter-
minals 87 and 30. The ohmmeter should not show
continuity between relay terminals 87A and 30.
(8) Disconnect jumper wires.
(9) Replace the relay if it did not pass the continu-
ity and resistance tests. If the relay passed the tests,
it operates properly. Check the remainder of the ASD
and fuel pump relay circuits. Refer to group 8W, Wir-
ing Diagrams.
CAMSHAFT AND CRANKSHAFT POSITION SENSOR
Refer to Group 8D, Ignition for Diagnosis and Test-
ing of Camshaft and Crankshaft Sensors.
ENGINE COOLANT TEMPERATURE SENSOR
(1) With the key off, disconnect wire harness con-
nector from coolant temperature sensor (Fig. 79) or
(Fig. 80).(2) Connect a high input impedance (digital) volt-
ohmmeter to terminals A and B (Fig. 81). The ohm-
meter should read as follows:
²Engine/Sensor at normal operating temperature
around 200ÉF should read approximately 700 to
1,000 ohms.
²Engine/Sensor at room temperature around 70ÉF
ohmmeter should read approximately 7,000 to 13,000
ohms.
(3) T
est the resistance of the wire harness between
the PCM 60-way connector terminal 28 and the sensor
harness connector. Also check for continuity between
PCM 60-way connector terminal 51 and the sensor har-
ness connector. Refer to Group 8W, Wiring diagrams for
circuit information. If the resistance is greater than 1
ohm, repair the wire harness as necessary.
HEATED OXYGEN SENSOR
Use an ohmmeter to test the heating element of
the oxygen sensors. Disconnect the electrical connec-
tor from each oxygen sensor. The white wires in the
sensor connector are the power and ground circuits
for the heater. Connect the ohmmeter test leads to
terminals of the white wires in the heated oxygen
sensor connector. Replace the heated oxygen sensor if
the resistance is not between 4 and 7 ohms.
IDLE AIR CONTROL (IAC) MOTOR TEST
To preform a complete test of IAC motor and its
circuitry, refer to DRB scan tool and the appropriate
Powertrain Diagnostics Procedures manual.
KNOCK SENSOR
The engine knock sensor is affected by a number of
factors. A few of these are: ignition timing, cylinder
pressure, fuel octane, etc. The knock sensor generates
an AC voltage whose amplitude increases with the
increase of engine knock. The knock sensor can be
tested with a digital voltmeter. The RMS voltage starts
Fig. 79 Engine Coolant Temperature Sensor
LocationÐSOHC
Fig. 80 Engine Coolant Temperature Sensor
LocationÐDOHC
Fig. 81 Engine Coolant Temperature Sensor
PLFUEL SYSTEM 14 - 47
DIAGNOSIS AND TESTING (Continued)

at about 20mVac (at about 700 rpm) and increases to
approximately 600 mVac (5000 rpm). If the output falls
outside of this range a DTC will be set.
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
To perform a complete test of the MAP sensor and
its circuitry, refer to the DRB scan tool and appropri-
ate Powertrain Diagnostics Procedures manual. To
test the MAP sensor only, refer to the following:
CAUTION: When testing the MAP sensor, be sure
that the harness wires are not damaged by the test
meter probes.
(1) Test the MAP sensor output voltage at the
MAP sensor connector between terminals 1 and 4
(Fig. 82). With the ignition switch ON and the engine
not running, output voltage should be 4 to 5 volts.
The voltage should drop to 1.5 to 2.1 volts with a hot,
neutral idle speed condition. If OK, go to next step. If
not OK, go to step 3.
(2) Test PCM terminal 36 for the same voltage
described in the previous step to verify wire harness
condition. Repair as required.
(3) Test the MAP sensor ground circuit at sensor
connector terminal 1 and PCM terminal 43. If OK, go
to next step. If not OK, repair as required.
(4) Test MAP sensor supply voltage between sen-
sor connector terminals 3 and 1 with the key ON.
The voltage should be approximately 5 volts (6.5V).
Five volts (6.5V) should also be at terminal 61 of the
PCM. If OK, replace MAP sensor. If not OK, repair or
replace the wire harness as required.
THROTTLE POSITION SENSOR
To perform a complete test of the this sensor and
its circuitry, refer to the DRB scan tool and appropri-
ate Powertrain Diagnostics Procedures manual. To
test the throttle position sensor only, refer to the fol-
lowing:
The Throttle Position Sensor (TPS) can be tested
with a digital voltmeter (DVM). The center terminal
of the sensor is the output terminal. One of the other
terminals is a 5 volt supply and the remaining ter-
minal is ground.
Connect the DVM between the center and sensor
ground terminal. Refer to Group 8W - Wiring Dia-
grams for correct pinout.
With the ignition switch in the ON position, check
the output voltage at the center terminal wire of the
connector. Check the output voltage at idle and at
Wide-Open-Throttle (WOT). At idle, TPS output volt-
age should be approximately 0.38 volts to 1.2 volts.
At wide open throttle, TPS output voltage should be
approximately 3.1 volts to 4.4 volts. The output volt-
age should gradually increase as the throttle plate
moves slowly from idle to WOT.
Check for spread terminals at the sensor and PCM
connections before replacing the TPS.
THROTTLE BODY MINIMUM AIR FLOW
(1) Turn ignition key to Off.
(2) Disconnect the PCV valve hose from the intake
manifold nipple (Fig. 83). Cap the PCV vacuum nip-
ple.
(3) Disconnect purge hose from the nipple on the
throttle body (Fig. 84).
(4) Use a piece of hose to attach Air Metering Ori-
fice 6457 (0.125 in. orifice) to the purge nipple on the
throttle body (Fig. 85).
(5) Ensure that all accessories are off.
Fig. 82 MAP Sensor Connector
Fig. 83 PCV Vacuum Nipple
14 - 48 FUEL SYSTEMPL
DIAGNOSIS AND TESTING (Continued)

(6) Connect the DRB scan tool to the data link
connector inside the passenger compartment.
(7) Run engine in Park or Neutral until the cooling
fan has cycled on and off at least once (180ÉF).
(8) Using the DRB scan tool, access Minimum Air-
flow Idle Speed.
(9) The following will then occur:
²Idle air control motor will fully close
²Idle spark advance will become fixed
²PCM will go open loop enriched
²DRB scan tool displays engine RPM
(10) If idle RPM is within the range shown in the
Idle Specification chart, throttle body minimum air-
flow is set correctly.
IDLE SPECIFICATION Ð2.0L ENGINEOdometer Reading Idle RPM
Below 1000 Miles.................550±1300 RPM
Above 1000 Miles.................600±1300 Miles
(11) If idle RPM is above specifications, use the
DRB scan tool to check idle air control motor opera-
tion. If idle air control motor is OK, replace throttle
body. If idle air flow is below specification, shut off
the engine and clean the throttle body as follows:
WARNING: CLEAN THROTTLE BODY IN A WELL
VENTILATED AREA. WEAR RUBBER OR BUTYL
GLOVES, DO NOT LET MOPAR PARTS CLEANER
COME IN CONTACT WITH EYES OR SKIN. AVOID
INGESTING THE CLEANER. WASH THOROUGHLY
AFTER USING CLEANER.
(a) Remove the throttle body from engine.
(b) While holding the throttle open, spray the
entire throttle body bore and the manifold side of
the throttle plate with Mopar Parts Cleaner.Only
use Mopar Parts Cleaner to clean the throttle
body.
(c) Using a soft scuff pad, clean the top and bot-
tom of throttle body bore and the edges and mani-
fold side of the throttle blade.The edges of the
throttle blade and portions of the throttle
bore that are closest to the throttle blade
when closed, must be free of deposits.
(d) Use compressed air to dry the throttle body.
(e) Inspect throttle body for foreign material.
(f) Install throttle body on manifold.
(g) Repeat steps 1 through 14. If the minimum
air flow is still not within specifications, the prob-
lem is not caused by the throttle body.
(12) Shut off engine.
(13) Remove Air Metering Orifice 6457. Install
purge hose.
(14) Remove cap from PCV valve. Connect hose to
PCV valve.
(15) Remove DRB scan tool.
VEHICLE SPEED SENSOR
To perform a complete test of the sensor and its
circuitry, refer to the DRB scan tool and appropriate
Powertrain Diagnostics Procedures Manual.
Fig. 84 Purge Hose
Fig. 85 Orifice 6457 Attached to Purge Nipple
PLFUEL SYSTEM 14 - 49
DIAGNOSIS AND TESTING (Continued)

PUSHING connector off the lever nail head (Fig. 88)
and (Fig. 90). DO NOT try to pull connector off per-
pendicular to the lever.
(6) Compress the retaining tabs on the cable and
slide cable out of bracket (Fig. 89).
(7) if equipped with speed control, hold throttle
lever in the wide open position. Using finger pressure
only, remove speed control cable by PUSHING con-
nector off the lever nail head (Fig. 88) and (Fig. 91).
DO NOT try to pull connector off perpendicular to
the lever.
(8) Compress the retaining tabs on the cable and
slide cable out of bracket (Fig. 89).
(9) Remove 2 screws holding cable mounting
bracket and support bracket.
(10) Remove TPS connector.
(11) Remove Idle Air Control motor connector.
(12) Remove EVAP purge hose.
(13) Remove throttle body mounting bolts. Remove
throttle body.(14) The rubber O-ring gasket on the intake man-
ifold is reusable. Wipe the O-ring clean before install-
ing throttle body (Fig. 92).
INSTALLATION
(1) Connect electrical connection to throttle body.
(2) Install throttle body on intake manifold.
Tighten mounting bolts 11.8 N.m (105 in. lbs.).
(3) Attach cable mounting bracket and support
bracket with 2 screws.
(4) Connect the EVAP purge hose.
(5) Install cable housing(s) retainer tabs into
bracket.
(6) Install throttle body cables using the following
procedures.
(7) From the engine compartment, rotate the
throttle lever forward to the wide open position and
install throttle cable clasp (Fig. 89).
(8) If equipped with speed control, rotate throttle
lever forward to the wide open position and slide
speed control cable connector onto nail head.
Fig. 89 Disconnecting Throttle Cable
Fig. 90 Transmission Kickdown Cable Connector
Fig. 91 Speed Control Cable Connector
Fig. 92 Re-Usable Throttle Body Gasket
PLFUEL SYSTEM 14 - 51
REMOVAL AND INSTALLATION (Continued)

(5) Install throttle body. Refer to Throttle Body in
this section.
(6) Connect the EVAP purge hose to the throttle
body nipple.
(7) Connect negative cable to battery.
MAP/IAT SENSORÐSOHC
The MAP/IAT sensor attaches to the intake mani-
fold plenum (Fig. 96).
REMOVAL
(1) Disconnect the electrical connector from the
MAP/IAT sensor.
(2) Remove sensor mounting screws.
(3) Remove sensor.
INSTALLATION
(1) Insert sensor into intake manifold while mak-
ing sure not to damage O-ring seal.
(2) Tighten mounting screws to 2 N´m (20 in. lbs)
torque for plastic manifold and 3 N´m (30 in. lbs.) for
aluminum manifold.
(3) Attach electrical connector to sensor.
MAP/IAT SENSORÐDOHC
The MAP/IAT sensor attaches to the intake mani-
fold plenum (Fig. 98).
REMOVAL
(1) Remove air inlet duct wing nut and duct from
intake manifold (Fig. 97).
(2) Disconnect the electrical connector from the
MAP/IAT sensor.
(3) Remove sensor mounting screws.
(4) Remove sensor.
INSTALLATION
(1) Insert sensor into intake manifold while mak-
ing sure not to damage O-ring seals.(2) Tighten mounting screws to 2 N´m (20 in. lbs)
torque foe a plastic manifold and 3 N´m (30 in. lbs)
for a aluminum manifold.
(3) Attach electrical connector to sensor.
(4) Install air inlet duct wing nut and duct from
intake manifold, insure that the duct does not inter-
fer with ignition cables.
DUTY CYCLE EVAP PURGE SOLENOID VALVE
The solenoid attaches to a bracket near the front
engine mount (Fig. 99). The solenoid will not operate
unless it is installed correctly.
REMOVAL
(1) Disconnect electrical connector from solenoid.
(2) Disconnect vacuum tubes from solenoid.
Fig. 95 Servicing Idle Air Control MotorFig. 96 MAP/IAT SensorÐSOHC
Fig. 97 Air Inlet DuctÐDOHC
PLFUEL SYSTEM 14 - 53
REMOVAL AND INSTALLATION (Continued)

with an anti-seize compound such as Loctitet771-64 or
equivalent.
INSTALLATION
New sensors have compound on the threads and do
not require an additional coating.
(1) Install sensor using an oxygen sensor crow foot
wrench such as Snap-On tool YA8875 or equivalent
(Fig. 101). Tighten the sensor to 28 N´m (20 ft. lbs.)
torque.
(2) Plug sensor connector.
(3) Lower vehicle.
DOWNSTREAM HEATED OXYGEN SENSOR
The downstream heated oxygen sensor threads into
the exhaust outlet pipe behind the catalytic convertor
(Fig. 102).
REMOVAL
(1) Raise vehicle.
(2) Disconnect electrical connector from sensor.
(3) Disconnect sensor electrical harness from clips
along body.
(4) Remove sensor using an oxygen sensor crow
foot wrench such as Snap-On tool YA8875 or equiva-
lent (Fig. 103).
(5) 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 Loctitet
771-64 or equivalent.
INSTALLATION
New sensors have compound on the threads and do
not require an additional coating.
(1) Install sensor using an oxygen sensor crow foot
wrench such as Snap-On tool YA8875 or equivalent
(Fig. 103). Tighten the sensor to 28 N´m (20 ft. lbs.)
torque.(2) Connect sensor electrical harness from clips
along body.
(3) Connect electrical connector from sensor.
(4) Lower vehicle.
AIR CLEANER ELEMENT
Neon vehicles do not use a heated air inlet system.
The PCM adjusts fuel injector pulse width and igni-
tion timing to compensate for different ambient tem-
peratures.
The air cleaner attaches to a bracket on the rear of
the cylinder head. An ambient air duct supplies
underhood air for the engine.
REMOVAL
(1) Remove air intake tube (Fig. 104) from air
cleaner and intake manifold (Fig. 105).
(2) Unfasten clasps on top of air cleaner housing.
Rotate front of housing forward then lift front away
from air cleaner housing (Fig. 106).
Fig. 101 Upstream Heated Oxygen Sensor Removal/
Installation
Fig. 102 Downstream Heated Oxygen Sensor
Fig. 103 Downstream Heated Oxygen Sensor
Removal/Installation
PLFUEL SYSTEM 14 - 55
REMOVAL AND INSTALLATION (Continued)