ESP DODGE NEON 2000 Service Manual PDF

MOPARtGASKET SEALANT
MopartGasket Sealant is a slow drying, perma-
nently soft sealer. This material is recommended for
sealing threaded fittings and gaskets against leakage
of oil and coolant. Can be used on threaded and
machined parts under all temperatures. This mate-
rial is used on engines with multi-layer steel (MLS)
cylinder head gaskets. This material also will pre-
vent corrosion. MopartGasket Sealant is available in
a 13 oz. aerosol can or 4 oz./16 oz. can w/applicator.
FORM-IN-PLACE GASKET AND SEALER
APPLICATION
Assembling parts using a form-in-place gasket
requires care but it's easier then using precut gas-
kets.
MopartGasket Maker material should be applied
sparingly 1 mm (0.040 in.) diameter or less of sealant
to one gasket surface. Be certain the material sur-
rounds each mounting hole. Excess material can eas-
ily be wiped off. Components should be torqued in
place within 15 minutes. The use of a locating dowel
is recommended during assembly to prevent smear-
ing material off the location.
MopartEngine RTV GEN II or ATF RTV gasket
material should be applied in a continuous bead
approximately 3 mm (0.120 in.) in diameter. All
mounting holes must be circled. For corner sealing, a
3.17 or 6.35 mm (1/8 or 1/4 in.) drop is placed in the
center of the gasket contact area. Uncured sealant
may be removed with a shop towel. Components
should be torqued in place while the sealant is still
wet to the touch (within 10 minutes). The usage of a
locating dowel is recommended during assembly to
prevent smearing material off the location.
MopartGasket Sealant in an aerosol can should be
applied using a thin, even coat sprayed completely
over both surfaces to be joined, and both sides of a
gasket. Then proceed with assembly. Material in a
can w/applicator can be brushed on evenly over the
sealing surfaces. Material in an aerosol can should be
used on engines with multi-layer steel gaskets.
ENGINE GASKET SURFACE PREPARATION
To ensure engine gasket sealing, proper surface
preparation must be performed, especially with the
use of aluminum engine components and multi-layer
steel cylinder head gaskets.
Neveruse the following to clean gasket surfaces:
²Metal scraper
²Abrasive pad or paper to clean cylinder block
and head
²High speed power tool with an abrasive pad or a
wire brush (Fig. 1)NOTE: Multi-Layer Steel (MLS) head gaskets
require a scratch free sealing surface.
Only use the following for cleaning gasket surfaces:
²Solvent or a commercially available gasket
remover
²Plastic or wood scraper (Fig. 1)
²Drill motor with 3M RolocyBristle Disc (white
or yellow) (Fig. 1)
CAUTION: Excessive pressure or high RPM can
damage the sealing surfaces. The mild (white, 120
grit) bristle disc is recommended. If necessary, the
medium (yellow, 80 grit) bristle disc may be used
on cast iron surfaces with care.
CRANKSHAFT DAMPER BOLT ACCESS PLUG
An access plug is located in the right splash shield
(Fig. 2). Remove the plug and insert the proper size
socket, extension and ratchet, when crankshaft rota-
tion is necessary.
ENGINE CORE PLUGS
REMOVAL
Using a blunt tool such as a drift or a screwdriver
and a hammer, strike the bottom edge of the cup
plug (Fig. 3). With the cup plug rotated, grasp firmly
with pliers or other suitable tool and remove plug
(Fig. 3).
Fig. 1 Proper Tool Usage For Surface Preparation
1 ± ABRASIVE PAD
2 ± 3M ROLOCYBRISTLE DISC
3 ± PLASTIC/WOOD SCRAPER
9 - 2 ENGINEPL
GENERAL INFORMATION (Continued)

make sure the dye is thoroughly mixed as indicated
with a bright yellow color under a black light.
(3) Using a black light, inspect the entire engine
for fluorescent dye, particularly at the suspected area
of oil leak. If the oil leak is found and identified,
repair per service manual instructions.
(4) If dye is not observed, drive the vehicle at var-
ious speeds for approximately 24 km (15 miles), and
repeat inspection.
(5)If the oil leak source is not positively
identified at this time, proceed with the air leak
detection test method as follows:
²Disconnect the fresh air hose (makeup air) at
the cylinder head cover and plug or cap the nipple on
the cover.
²Remove the PCV valve hose from the cylinder
head cover. Cap or plug the PCV valve nipple on the
cover.
²Attach an air hose with pressure gauge and reg-
ulator to the dipstick tube.
CAUTION: Do not subject the engine assembly to
more than 20.6 kpa (3 PSI) of test pressure.
²Gradually apply air pressure from 1 psi to 2.5
psi maximum while applying soapy water at the sus-
pected source. Adjust the regulator to the suitable
test pressure that provides the best bubbles which
will pinpoint the leak source. If the oil leak is
detected and identified, repair per service manual
procedures.
²If the leakage occurs at the crankshaft rear oil
seal area, refer to the section, Inspection for Rear
Seal Area Leak.
(6) If no leaks are detected, turn off the air supply.
Remove the air hose, all plugs, and caps. Install the
PCV valve and CCV hose. Proceed to next step.
(7) Clean the oil off the suspect oil leak area using
a suitable solvent. Drive the vehicle at various
speeds approximately 24 km (15 miles). Inspect the
engine for signs of an oil leak by using a black light.
INSPECTION FOR REAR SEAL AREA LEAKS
Since it is sometimes difficult to determine the
source of an oil leak in the rear seal area of theengine, a more involved inspection is necessary. The
following steps should be followed to help pinpoint
the source of the leak.
If the leakage occurs at the crankshaft rear oil seal
area:
(1) Disconnect the battery.
(2) Raise the vehicle.
(3) Remove torque converter or clutch housing
cover and inspect rear of block for evidence of oil.
Use a black light to check for the oil leak. If a leak is
present in this area remove transmission for further
inspection.
(a) Circular spray pattern generally indicates
seal leakage or crankshaft damage.
(b) Where leakage tends to run straight down,
possible causes are a porous block, oil galley cup
plug, bedplate to cylinder block mating surfaces
and seal bore. See proper repair procedures for
these items.
(4) If no leaks are detected, pressurized the crank-
case as previously described.
CAUTION: Do not exceed 20.6 kPa (3 psi).
(5) If the leak is not detected, very slowly turn the
crankshaft and watch for leakage. If a leak is
detected between the crankshaft and seal while
slowly turning the crankshaft, it is possible the
crankshaft seal surface is damaged. The seal area on
the crankshaft could have minor nicks or scratches
that can be polished out with emery cloth.
CAUTION: Use extreme caution when crankshaft
polishing is necessary to remove minor nicks and
scratches. The crankshaft seal flange is especially
machined to complement the function of the rear oil
seal.
(6) For bubbles that remain steady with shaft
rotation, no further inspection can be done until dis-
assembled.
(7) After the oil leak root cause and appropriate
corrective action have been identified, refer to Crank-
shaft Oil SealÐRear for proper replacement proce-
dures.
9 - 10 ENGINEPL
DIAGNOSIS AND TESTING (Continued)

der head. The rocker shafts route oil to the rocker
arms/hydraulic lash adjuster assemblies.
SPLASH LUBRICATION
Oil returning to the pan from pressurized compo-
nents supplies lubrication to the valve stems. Cylin-
der bores and wrist pins are splash lubricated from
directed slots on the connecting rod thrust collars.
DIAGNOSIS AND TESTING
CHECKING ENGINE OIL PRESSURE
(1) Remove oil pressure switch and install gauge
assembly C-3292 with adaptor.
(2) Run engine until thermostat opens.
CAUTION: If oil pressure is 0 at idle, Do Not per-
form the 3000 RPM test in the next step.
(3) Oil Pressure:Curb Idle25 kPa (4 psi) mini-
mum3000 RPM170-550 kPa (25-80 psi).
(4) If oil pressure is 0 at idle. Shut off engine,
check for pressure relief valve stuck open, a clogged
oil pick-up screen or a damaged oil pick-up tube
O-ring.
SERVICE PROCEDURES
CYLINDER BORE AND PISTON SIZING
The cylinder walls should be checked for out-of-
round and taper with recommended tool C-119 or
equivalent (Fig. 3). The cylinder bore out-of-roundand cylinder bore taper must within service limits.
Refer to Engine Specifications in this section. If the
cylinder walls are badly scuffed or scored, the cylin-
der block should be rebored and honed, and new pis-
tons and rings fitted. Whatever type of boring
equipment is used, boring and honing operations
should be closely coordinated with the fitting of pis-
tons and rings in order to maintain specified clear-
ances.Refer to Honing Cylinder Bores in the
Standard Service Procedures for procedures.
Measure the cylinder bore at three levels in direc-
tions A and B (Fig. 3). Top measurement should be
10 mm (3/8 inch) down and bottom measurement
should be 10 mm (3/8 inch.) up from bottom of bore.
Refer to Engine Specifications in this section for cyl-
inder block specifications.
SIZING PISTONS
Piston and cylinder wall must be clean and dry.
Piston diameter should be measured 90 degrees to
piston pin about 17.5 mm (11/16 inch) from the bot-
tom of the skirt as shown in (Fig. 4). Cylinder bores
should be measured halfway down the cylinder bore
and transverse to the engine crankshaft center line
shown in (Fig. 3). Correct piston to bore clearance
must be established in order to assure quiet and eco-
nomical operation. Refer to Engine Specifications in
this section for cylinder block and piston specifica-
tions.
DaimlerChrysler engines use pistons designed spe-
cifically for each engine model. Clearance and sizing
locations vary with respect to engine model.
Fig. 2 Engine Lubrication SystemÐ SOHC
Fig. 3 Checking Cylinder Bore Size
9 - 18 2.0L SOHC ENGINEPL
DESCRIPTION AND OPERATION (Continued)

INSPECT CYLINDER HEAD FOR THE FOLLOWING:
NOTE:
²Check oil feed holes for blockage.
²Inspect cylinder head camshaft bearings for
wear, Refer to Cylinder Head, Inspection and Clean-
ing.
²Check camshaft bearing journals for scratches
and worn areas. If light scratches are present, they
may be removed with 400 grit sand paper. If deep
scratches are present, replace the camshaft and
check the cylinder head for damage. Replace the
cylinder head if worn or damaged. Check the lobes
for pitting and wear. If the lobes show signs of
wear, check the corresponding rocker arm roller for
wear or damage. Replace rocker arm/hydraulic lash
adjuster if worn or damaged. If lobes show signs of
pitting on the nose, flank or base circle; replace the
camshaft.
INSTALLATION
(1) Lubricate the camshaft journals with oil and
install camshaftwithoutrocker arm assemblies
installed.
(2) Install camshaft target magnet into the end of
the camshaft. Tighten mounting screw to 3.4 N´m (30
in. lbs.).
(3) Install camshaft position sensor and tighten
mounting screws to 9 N´m (80 in. lbs.).
(4) Measure camshaft end play using the following
procedure:
(a) Mount dial indicator C-3339 or equivalent, to
a stationary point on cylinder head (Fig. 46).
(b) Using a suitable tool, move camshaft to rear-
ward limits of travel.
(c) Zero the dial indicator.
(d) Move camshaft forward to limits of travel
and read dial indicator.
(e) End play travel: 0.13±0.33 mm (0.005±0.013
in.).
(5) Install front camshaft seal. Camshaft must be
installed before the camshaft seal is installed. Refer
to procedure in this section.
(6) Install cylinder head. Refer to procedure in this
section.
(7) Install rear timing belt cover.
(8) Install camshaft sprocket and tighten to 115
N´m (85 ft. lbs.).
(9) Install timing belt tensioner and timing belt.
Refer to procedures in this section.
(10) Install rocker arm assemblies in correct order
as removed. Tighten the rocker arm assemblies in
sequence shown in (Fig. 47) to 28 N´m (250 in. lbs.).
(11) Install cylinder head cover and tighten fasten-
ers to 12 N´m (105 in. lbs.).(12) Install ignition coil and spark plug cables.
Tighten ignition coil fasteners to 12 N´m (105 in.
lbs.).
(13) Perform camshaft and crankshaft timing
relearn procedure as follows:
²Connect the DRB scan tool to the data link
(diagnostic) connector. This connector is located in
the passenger compartment; at the lower edge of
instrument panel; near the steering column.
²Turn the ignition switch on and access the ªmis-
cellaneousº screen.
²Select ªre-learn cam/crankº option and follow
directions on DRB screen.
ROCKER ARM/HYDRAULIC LASH ADJUSTER
REMOVAL
(1) Remove cylinder head cover. Refer to procedure
in this section.
(2) Identify the rocker arm shaft assemblies before
removal.
(3) Loosen the attaching fasteners. Remove rocker
arm shaft assemblies from cylinder head.
(4) Identify the rocker arms spacers and retainers
for reassembly. Disassemble the rocker arm assem-
blies by removing the attaching bolts from the shaft
(Fig. 48).
Fig. 46 Camshaft End Play
Fig. 47 Rocker Arm Shaft Tightening Sequence
9 - 34 2.0L SOHC ENGINEPL
REMOVAL AND INSTALLATION (Continued)

a 0.762 mm (0.030 in.) spacer under the valve spring
seat to bring spring height back within specification.
(5) Install rocker arm shafts as previously
described in this section.
(6) Checking dry lash. Dry lash is the amount of
clearance that exists between the base circle of an
installed cam and the rocker arm roller when the
adjuster is drained of oil and completely collapsed.
Specified dry lash is 1.17 mm (0.046 in.) for intake
and 1.28 mm (0.050 in.) for exhaust. After performing
dry lash check, refill adjuster with oil and allow 10
minutes for adjuster(s) to bleed down before rotating
cam.
CLEANING AND INSPECTION
INTAKE MANIFOLD
CLEAN AND INSPECT
Check for:
²Inspect manifold for cracks or distortions.
²Check for torn or missing O-rings at the mating
surface of the manifold (Fig. 125).
EXHAUST MANIFOLD
CLEAN AND INSPECT
(1) Discard gasket and clean all gasket surfaces of
manifolds and cylinder head.
(2) Test manifold gasket surfaces for flatness with
straight edge. Surface must be flat within 0.15 mm
per 300 mm (.006 in. per foot) of manifold length.
(3) Inspect manifolds for cracks or distortion.
Replace manifold if necessary.
CYLINDER HEAD AND CAMSHAFT JOURNALS
CLEANING
Remove all gasket material from cylinder head. Be
careful not to gouge or scratch the aluminum head
sealing surface. Clean all engine oil passages.
To ensure engine gasket sealing, proper surface
preparation must be performed, especially with the
use of aluminum engine components and multi-layer
steel cylinder head gaskets.
Neveruse the following to clean aluminum gasket
surfaces:
²Metal scraper
²Abrasive pad or paper to clean cylinder block
and head
²High speed power tool with an abrasive pad or a
wire brush (Fig. 126)
NOTE: Multi-Layer Steel (MLS) head gaskets
require a scratch free sealing surface.
Only use the following for cleaning gasket surfaces:
²Solvent or a commercially available gasket
remover
²Plastic or wood scraper (Fig. 126)
²Drill motor with 3M RolocyBristle Disc (white
or yellow) (Fig. 126)
CAUTION: Excessive pressure or high RPM can
damage the sealing surfaces. The mild (white, 120
grit) bristle disc is recommended. If necessary, the
medium (yellow, 80 grit) bristle disc may be used
on cast iron surfaces with care.
Fig. 125 Intake Manifold O-Rings
1 ± INTAKE MANIFOLD O-RING GASKETS
Fig. 126 Proper Tool Usage For Surface Preparation
1 ± ABRASIVE PAD
2 ± 3M ROLOCYBRISTLE DISC
3 ± PLASTIC/WOOD SCRAPER
PL2.0L SOHC ENGINE 9 - 63
DISASSEMBLY AND ASSEMBLY (Continued)

INSPECTING CYLINDER HEAD
Check cylinder head for flatness with a straight
edge. Cylinder head must be flat within 0.1 mm
(0.004 in.) (Fig. 127).
INSPECTING CAMSHAFT JOURNALS
Inspect cylinder head camshaft bearings for wear.
Check the camshaft journals for scratches and worn
areas. If light scratches are present, they may be
removed with 400 grit sand paper. If deep scratches
are present, replace the camshaft and check the cyl-
inder head for damage. Replace the cylinder head if
worn or damaged. Check the lobes for pitting and
wear. If the lobes show signs of wear, check the cor-
responding rocker arm roller for wear or damage.
Replace rocker arm/hydraulic lash adjuster if worn or
damaged. If lobes show signs of pitting on the nose,
flank or base circle; replace the camshaft.
OIL PUMP
(1) Clean all parts thoroughly. Mating surface of
the oil pump should be smooth. Replace pump cover
if scratched or grooved.
(2) Lay a straightedge across the pump cover sur-
face (Fig. 128). If a 0.076 mm (0.003 inch.) feeler
gauge can be inserted between cover and straight
edge, cover should be replaced.
(3) Measure thickness and diameter of outer rotor.
If outer rotor thickness measures 7.64 mm (0.301
inch.) or less (Fig. 129), or if the diameter is 79.95
mm (3.148 inches) or less, replace outer rotor.
(4) If inner rotor measures 7.64 mm (0.301 inch) or
less replace inner rotor (Fig. 130).
(5) Slide outer rotor into pump housing, press to
one side with fingers and measure clearance between
rotor and housing (Fig. 131). If measurement is 0.39
Fig. 127 Checking Cylinder Head Flatness
1 ± FEELER GAUGE
2 ± STRAIGHT EDGE
Fig. 128 Checking Oil Pump Cover Flatness
1 ± OIL PUMP BODY
2 ± OIL PUMP COVER
3 ± OUTER ROTOR
4 ± INNER ROTOR
Fig. 129 Measuring Outer Rotor Thickness
Fig. 130 Measuring Inner Rotor Thickness
9 - 64 2.0L SOHC ENGINEPL
CLEANING AND INSPECTION (Continued)

REFORMULATED GASOLINE
Many areas of the country require the use of
cleaner burning gasoline referred to as ªreformulat-
edº gasoline. Reformulated gasoline contain oxygen-
ates, and are specifically blended to reduce vehicle
emissions and improve air quality.
DaimlerChrysler Corporation strongly supports the
use of reformulated gasoline. Properly blended refor-
mulated gasoline will provide excellent performance
and durability for the engine and fuel system compo-
nents.
GASOLINE/OXYGENATE BLENDS
Some fuel suppliers blend unleaded gasoline with
oxygenates such as 10% ethanol, MTBE, and ETBE.
Oxygenates are required in some areas of the country
during the winter months to reduce carbon monoxide
emissions. Fuels blended with these oxygenates may
be used in your vehicle.
CAUTION: DO NOT use gasoline containing METH-
ANOL. Gasoline containing methanol may damage
critical fuel system components.
MMT
MMT is a manganese-containing metallic additive
that is blended into some gasoline to increase octane.
Gasoline blended with MMT provide no performance
advantage beyond gasoline of the same octane num-
ber without MMT. Gasoline blended with MMT
reduce spark plug life and reduce emission system
performance in some vehicles. DaimlerChrysler rec-
ommends that gasoline without MMT be used in your
vehicle. The MMT content of gasoline may not be
indicated on the gasoline pump; therefore, you should
ask your gasoline retailer whether or not his/her gas-
oline contains MMT.
It is even more important to look for gasoline with-
out MMT in Canada because MMT can be used at
levels higher than allowed in the United States.
MMT is prohibited in Federal and California refor-
mulated gasoline.
SULFUR IN GASOLINE
If you live in the northeast United States, your
vehicle may have been designed to meet California
low emission standards with clean-burning, low-sul-
fur, California gasoline. Gasoline sold outside of Cal-
ifornia is permitted to have higher sulfur levels
which may affect the performance of the vehicle's cat-
alytic converter. This may cause the Check Engine or
Service Engine Soon light to illuminate.
Illumination of either light while operating on high
sulfur gasoline does not necessarily mean your emis-
sion control system is malfunctioning. DaimlerChrysler
recommends that you try a different brand of unleadedgasoline having lower sulfur to determine if the prob-
lem is fuel related prior to returning your vehicle to an
authorized dealer for service.
CAUTION: If the Check Engine or Service Engine
Soon light is flashing, immediate service is
required; see on-board diagnostics system section.
MATERIALS ADDED TO FUEL
All gasoline sold in the United States and Canada
are required to contain effective detergent additives.
Use of additional detergents or other additives is not
needed under normal conditions.
FUEL SYSTEM CAUTIONS
CAUTION: Follow these guidelines to maintain your
vehicle's performance:
²The use of leaded gas is prohibited by Federal
law. Using leaded gasoline can impair engine perfor-
mance, damage the emission control system, and
could result in loss of warranty coverage.
²An out-of-tune engine, or certain fuel or ignition
malfunctions, can cause the catalytic converter to
overheat. If you notice a pungent burning odor or
some light smoke, your engine may be out of tune or
malfunctioning and may require immediate service.
Contact your dealer for service assistance.
²When pulling a heavy load or driving a fully
loaded vehicle when the humidity is low and the tem-
perature is high, use a premium unleaded fuel to
help prevent spark knock. If spark knock persists,
lighten the load, or engine piston damage may result.
²The use of fuel additives which are now being
sold as octane enhancers is not recommended. Most
of these products contain high concentrations of
methanol. Fuel system damage or vehicle perfor-
mance problems resulting from the use of such fuels
or additives is not the responsibility of
DaimlerChrysler Corporation and may not be covered
under the new vehicle warranty.
NOTE: Intentional tampering with emissions control
systems can result in civil penalties being assessed
against you.
GASOLINE/OXYGENATE BLENDS
OPERATION
Some fuel suppliers blend unleaded gasoline with
materials that contain oxygen such as alcohol, MTBE
(Methyl Tertiary Butyl Ether) and ETBE (Ethyl Ter-
tiary Butyl Ether). Oxygenates are required in some
areas of the country during winter months to reduce
14 - 2 FUEL SYSTEMPL
DESCRIPTION AND OPERATION (Continued)

carbon monoxide emissions. The type and amount of
oxygenate used in the blend is important.
The following are generally used in gasoline
blends:
Ethanol- (Ethyl or Grain Alcohol) properly
blended, is used as a mixture of 10 percent ethanol
and 90 percent gasoline. Gasoline blended with etha-
nol may be used in your vehicle.
MTBE/ETBE- Gasoline and MTBE (Methyl Ter-
tiary Butyl Ether) blends are a mixture of unleaded
gasoline and up to 15 percent MTBE. Gasoline and
ETBE (Ethyl Tertiary Butyl Ether) are blends of gas-
oline and up to 17 percent ETBE. Gasoline blended
with MTBE or ETBE may be used in your vehicle.
Methanol- Methanol (Methyl or Wood Alcohol) is
used in a variety of concentrations blended with
unleaded gasoline. You may encounter fuels contain-
ing 3 percent or more methanol along with other
alcohols called cosolvents.
DO NOT USE GASOLINE CONTAINING
METHANOL.
Use of methanol/gasoline blends may result in
starting and driveability problems and damage criti-
cal fuel system components.
Problems that are the result of using methanol/
gasoline blends are not the responsibility of
DaimlerChrysler Corporation and may not be covered
by the vehicle warranty.
Reformulated Gasoline
Many areas of the country are requiring the use of
cleaner-burning fuel referred to asReformulated
Gasoline. Reformulated gasoline are specially
blended to reduce vehicle emissions and improve air
quality.
DaimlerChrysler Corporation strongly supports the
use of reformulated gasoline whenever available.
Although your vehicle was designed to provide opti-
mum performance and lowest emissions operating on
high quality unleaded gasoline, it will perform
equally well and produce even lower emissions when
operating on reformulated gasoline.
Materials Added to Fuel
Indiscriminate use of fuel system cleaning agents
should be avoided. Many of these materials intended
for gum and varnish removal may contain active sol-
vents of similar ingredients that can be harmful to
fuel system gasket and diaphragm materials.
FUEL DELIVERY SYSTEM
OPERATION
The fuel delivery system consists of: the electric
fuel pump, fuel filter/fuel pressure regulator, fuel
tubes/lines/hoses, fuel rail, fuel injectors, fuel tank,
accelerator pedal and throttle cable.A fuel return system is used on all models (all
engines). Fuel is returned through the fuel pump
module and back into the fuel tank through the fuel
filter/fuel pressure regulator. A separate fuel return
line from the engine to the tank is no longer used
with any engine.
The fuel tank assembly consists of: the fuel tank,
filler tube, fuel gauge sending unit/electric fuel pump
module, a rollover valve(s) and a pressure-vacuum
filler cap.
Also to be considered part of the fuel system is the
evaporation control system or Onboard Refueling
Vapor recovery (ORVR). This is designed to reduce
the emission of fuel vapors into the atmosphere. The
description and function of the Evaporative Control
System is found in the Emission Control Systems
section.
FUEL PUMP MODULE
DESCRIPTION
The fuel pump module is installed in the fuel tank
(Fig. 1).
OPERATION
The fuel pump module contains the following:
²Electric fuel pump
²Fuel pump reservoir
²Inlet strainer
²Fuel filter/pressure regulator
²Fuel gauge sending unit
²Fuel supply line connection
Fig. 1 Fuel Pump Module
1 ± FUEL FILTER/PRESSURE REGULATOR
2 ± FUEL LEVEL SENSOR
3 ± FUEL RESERVOIR
4 ± INLET STRAINER
5 ± FLOAT
PLFUEL SYSTEM 14 - 3
DESCRIPTION AND OPERATION (Continued)

DESCRIPTION AND OPERATION
INJECTION SYSTEM
All engines used in this section have a sequential
Multi-Port Electronic Fuel Injection system. The MPI
system is computer regulated and provides precise
air/fuel ratios for all driving conditions. The Power-
train Control Module (PCM) operates the fuel injec-
tion system.
The PCM regulates:
²Ignition timing
²Air/fuel ratio
²Emission control devices
²Cooling fan
²Charging system
²Idle speed
²Vehicle speed control
Various sensors provide the inputs necessary for
the PCM to correctly operate these systems. In addi-
tion to the sensors, various switches also provide
inputs to the PCM.
All inputs to the PCM are converted into signals.
The PCM can adapt its programming to meet chang-
ing operating conditions.
Fuel is injected into the intake port above the
intake valve in precise metered amounts through
electrically operated injectors. The PCM fires the
injectors in a specific sequence. Under most operat-
ing conditions, the PCM maintains an air fuel ratio
of 14.7 parts air to 1 part fuel by constantly adjust-
ing injector pulse width. Injector pulse width is the
length of time the injector is open.
The PCM adjusts injector pulse width by opening
and closing the ground path to the injector. Engine
RPM (speed) and manifold absolute pressure (air
density) are the primary inputs that determine injec-
tor pulse width.
MODES OF OPERATION
OPERATION
As input signals to the PCM change, the PCM
adjusts its response to output devices. For example,
the PCM must calculate a different injector pulse
width and ignition timing for idle than it does for
Wide Open Throttle (WOT). There are several differ-
ent modes of operation that determine how the PCM
responds to the various input signals.
There are two different areas of operation, OPEN
LOOP and CLOSED LOOP.
During OPEN LOOP modes the PCM receives
input signals and responds according to preset PCM
programming. Inputs from the upstream and down-
stream heated oxygen sensors are not monitored dur-
ing OPEN LOOP modes, except for heated oxygensensor diagnostics (they are checked for shorted con-
ditions at all times).
During CLOSED LOOP modes the PCM monitors
the inputs from the upstream and downstream
heated oxygen sensors. The upstream heated oxygen
sensor input tells the PCM if the calculated injector
pulse width resulted in the ideal air-fuel ratio of 14.7
to one. By monitoring the exhaust oxygen content
through the upstream heated oxygen sensor, the
PCM can fine tune injector pulse width. Fine tuning
injector pulse width allows the PCM to achieve opti-
mum fuel economy combined with low emissions.
For the PCM to enter CLOSED LOOP operation,
the following must occur:
(1) Engine coolant temperature must be over 35ÉF.
²If the coolant is over 35É the PCM will wait 44
seconds.
²If the coolant is over 50ÉF the PCM will wait 38
seconds.
²If the coolant is over 167ÉF the PCM will wait
11 seconds.
(2) For other temperatures the PCM will interpo-
late the correct waiting time.
(3) O2 sensor must read either greater than 0.745
volts or less than 0.1 volt.
(4) The multi-port fuel injection systems has the
following modes of operation:
²Ignition switch ON (Zero RPM)
²Engine start-up
²Engine warm-up
²Cruise
²Idle
²Acceleration
²Deceleration
²Wide Open Throttle
²Ignition switch OFF
(5) The engine start-up (crank), engine warm-up,
deceleration with fuel shutoff and wide open throttle
modes are OPEN LOOP modes. Under most operat-
ing conditions, the acceleration, deceleration (with
A/C on), idle and cruise modes,with the engine at
operating temperatureare CLOSED LOOP modes.
IGNITION SWITCH ON (ZERO RPM) MODE
When the ignition switch activates the fuel injec-
tion system, the following actions occur:
²The PCM monitors the engine coolant tempera-
ture sensor and throttle position sensor input. The
PCM determines basic fuel injector pulse width from
this input.
²The PCM determines atmospheric air pressure
from the MAP sensor input to modify injector pulse
width.
When the key is in the ON position and the engine
is not running (zero rpm), the Auto Shutdown (ASD)
and fuel pump relays de-energize after approximately
14 - 22 FUEL SYSTEMPL

²All inputs monitored for proper voltage range.
²All monitored components (refer to the Emission
section for On-Board Diagnostics).
The PCM compares the upstream and downstream
heated oxygen sensor inputs to measure catalytic
convertor efficiency. If the catalyst efficiency drops
below the minimum acceptable percentage, the PCM
stores a diagnostic trouble code in memory.
During certain idle conditions, the PCM may enter
a variable idle speed strategy. During variable idle
speed strategy the PCM adjusts engine speed based
on the following inputs.
²A/C sense
²Battery voltage
²Battery temperature
²Engine coolant temperature
²Engine run time
²Power steering pressure switch
²Vehicle mileage
ACCELERATION MODE
This is a CLOSED LOOP mode. The PCM recog-
nizes an abrupt increase in Throttle Position sensor
output voltage or MAP sensor output voltage as a
demand for increased engine output and vehicle
acceleration. The PCM increases injector pulse width
in response to increased fuel demand.
DECELERATION MODE
This is a CLOSED LOOP mode. During decelera-
tion the following inputs are received by the PCM:
²A/C pressure transducer
²A/C sense
²Battery voltage
²Intake air temperature
²Engine coolant temperature
²Crankshaft position (engine speed)
²Exhaust gas oxygen content (upstream heated
oxygen sensor)
²Knock sensor
²Manifold absolute pressure
²Power steering pressure switch
²Throttle position
²IAC motor control changes in response to MAP
sensor feedback.
The PCM may receive a closed throttle input from
the Throttle Position Sensor (TPS) when it senses an
abrupt decrease in manifold pressure. This indicates
a hard deceleration. In response, the PCM may
momentarily turn off the injectors. This helps
improve fuel economy, emissions and engine braking.
If decel fuel shutoff is detected, downstream oxy-
gen sensor diagnostics is performed.WIDE-OPEN-THROTTLE MODE
This is an OPEN LOOP mode. During wide-open-
throttle operation, the following inputs are received
by the PCM:
²Intake air temperature
²Engine coolant temperature
²Engine speed
²Knock sensor
²Manifold absolute pressure
²Throttle position
When the PCM senses a wide-open-throttle condi-
tion through the Throttle Position Sensor (TPS) it de-
energizes the A/C compressor clutch relay. This
disables the air conditioning system.
The PCM does not monitor the heated oxygen sen-
sor inputs during wide-open-throttle operation except
for downstream heated oxygen sensor and both
shorted diagnostics. The PCM adjusts injector pulse
width to supply a predetermined amount of addi-
tional fuel.
IGNITION SWITCH OFF MODE
When the operator turns the ignition switch to the
OFF position, the following occurs:
²All outputs are turned off, unless 02 Heater
Monitor test is being run. Refer to the Emission sec-
tion for On-Board Diagnostics.
²No inputs are monitored except for the heated
oxygen sensors. The PCM monitors the heating ele-
ments in the oxygen sensors and then shuts down.
SYSTEM DIAGNOSIS
OPERATION
The PCM can test many of its own input and out-
put circuits. If the PCM senses a fault in a major
system, the PCM stores a Diagnostic Trouble Code
(DTC) in memory.
For DTC information see On-Board Diagnostics.
POWER DISTRIBUTION CENTER
The Power Distribution Center (PDC) is located
next to the battery (Fig. 1). The PDC contains the
starter relay, radiator fan relay, A/C compressor
clutch relay, auto shutdown relay, fuel pump relay
and several fuses.
POWERTRAIN CONTROL MODULE
The Powertrain Control Module (PCM) is a digital
computer containing a microprocessor (Fig. 2). The
PCM receives input signals from various switches
and sensors that are referred to as PCM Inputs.
Based on these inputs, the PCM adjusts various
engine and vehicle operations through devices that
are referred to as PCM Outputs.
PCM Inputs:
14 - 24 FUEL SYSTEMPL
DESCRIPTION AND OPERATION (Continued)