check engine light DODGE NEON 2000 Service Owner's Manual

ENGINE DIAGNOSISÐPERFORMANCE
CONDITION POSSIBLE CAUSE CORRECTION
ENGINE WILL NOT START 1. Weak battery. 1. Test battery. Charge or replace
as necessary. Refer to Group 8A,
Battery.
2. Corroded or loose battery
connections.2. Clean and tighten battery
connections. Apply a coat of light
mineral grease to terminals.
3. Faulty starter. 3. Test starting system. Refer to
Group 8B, Starting.
4. Faulty coil(s) or control unit. 4. Test and replace as needed.
Refer to Group 8D, Ignition System.
5. Incorrect spark plug gap. 5. Set gap. Refer to Group 8D,
Ignition System.
6. Contamination in fuel system. 6. Clean system and replace fuel
filter.
7. Faulty fuel pump. 7. Test fuel pump and replace as
needed. Refer to Group 14, Fuel
System.
8. Incorrect engine timing. 8. Check for a skipped timing
belt/chain.
ENGINE STALLS OR IDLES
ROUGH1. Idle speed too low. 1. Test minimum air flow. Refer to
Group 14, Fuel System.
2. Incorrect fuel mixture. 2. Refer to Group 14, Fuel System.
3. Intake manifold leakage. 3. Inspect intake manifold, manifold
gasket, and vacuum hoses.
4. Faulty coil(s). 4. Test and replace as necessary.
Refer to Group 8D, Ignition System.
ENGINE LOSS OF POWER 1. Dirty or incorrectly gapped plugs. 1. Clean plugs and set gap. Refer to
Group 8D, Ignition System.
2. Contamination in fuel system. 2. Clean system and replace fuel
filter.
3. Faulty fuel pump. 3. Test and replace as necessary.
Refer to Group 14, Fuel System.
4. Incorrect valve timing. 4. Correct valve timing.
5. Leaking cylinder head gasket. 5. Replace cylinder head gasket.
6. Low compression. 6. Test compression of each
cylinder.
7. Burned, warped, or pitted valves. 7. Replace valves.
8. Plugged or restricted exhaust
system.8. Install new parts, as necessary.
9. Faulty coil(s). 9. Test and replace as necessary.
Refer to Group 8D, Ignition System.
PLENGINE 9 - 11
DIAGNOSIS AND TESTING (Continued)

(2) Install intake manifold to lower support
bracket bolts (Fig. 31). Tighten bolts to 11 N´m (95
in. lbs.).
(3) Remove covering from fuel injector holes and
insure the holes are clean. Install fuel rail assembly
to intake manifold. Tighten screws to 23 N´m (200 in.
lbs.).
(4) Connect PCV and brake booster hoses.
(5) Inspect quick connect fittings for damage,
replace if necessary Refer to Group 14, Fuel System
for procedure. Apply a light amount of clean engine
oil to fuel inlet tube. Connect fuel supply hose to fuel
rail assembly. Check connection by pulling on connec-
tor to insure it locked into position.
(6) Connect Manifold Absolute Pressure (MAP)
Sensor wiring connector (Fig. 29).(7) Connect knock sensor connector, and wiring at
starter.
(8) Install inlet air duct to intake manifold and
throttle body. Tighten clamp to 3 N´m (30 in. lbs.).
(9) Connect negative cable to battery.
(10) With the DRB scan tool use ASD Fuel System
Test to pressurize system to check for leaks.
Fig. 29 MAP Sensor
Fig. 30 Knock Sensor
1 ± KNOCK SENSOR
2 ± STARTER MOTOR
Fig. 31 Intake Manifold Lower Supports
1 ± BOLT
2 ± BRACKET
3 ± BRACKET
4 ± BOLT
Fig. 32 Intake Manifold Tightening Sequence
PL2.0L SOHC ENGINE 9 - 29
REMOVAL AND INSTALLATION (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)

wrench until ping is heard. Take reading on torque
wrench at this instant. Multiply this reading by two.
This will give the spring load at test length. Frac-
tional measurements are indicated on the table for
finer adjustments. Discard the springs that do not
meet specifications. The following specifications apply
to both intake and exhaust valve springs:
²Valve Closed Nominal TensionÐ70 lbs. @ 39.8
mm (1.57 in.)
²Valve Closed Nominal TensionÐ160 lbs. @ 32.6
mm (1.28 in.)
(2) Verify springs are not distorted with a steel
square and surface plate, check springs from both
ends. If the spring is more than 1.5 mm (1/16 in.) out
of square, install a new spring.
REFACING VALVES AND VALVE SEATS
(1) The intake and exhaust valve seats and valve
face have a 45 degree angle.
(2) Inspect the remaining margin after the valves
are refaced (Fig. 121). Intake valves with less than
0.95 mm (1/32 in.) margin and exhaust valves with
less than 1.05 mm (3/64 in.) margin should be dis-
carded.
(3) When refacing valve seats, it is important that
the correct size valve guide pilot be used for reseat-
ing stones. A true and complete surface must be
obtained. For specifications, refer to Engine Specifi-
cations in this section.
(4) Measure the concentricity of valve seat and
valve guide using a valve seat runout dial indicator.
Total runout should not exceed 0.051 mm (0.002 in.)
(total indicator reading).
(5) Inspect the valve seat with Prussian blue to
determine where the valve contacts the seat. To do
this, coat valve seatLIGHTLYwith Prussian blue
Fig. 118 Checking Wear on Valve GuideÐTypical
1±TOP
2 ± MIDDLE
3 ± BOTTOM
4 ± CUT AWAY VIEW OF VALVE GUIDE MEASUREMENT
LOCATIONS
Fig. 119 Valve Guide Height
1 ± VALVE GUIDE
2 ± 13.25 - 13.75 MM (0.521-0.541 in.)
3 ± SPRING SEAT
Fig. 120 Valve Spring Testing
1 ± TORQUE WRENCH
2 ± VALVE SPRING TESTER
Fig. 121 Intake and Exhaust Valve Refacing
1 ± VALVE FACE
2 ± VALVE MARGIN
PL2.0L SOHC ENGINE 9 - 61
DISASSEMBLY AND ASSEMBLY (Continued)

then set valve in place. Rotate the valve with light
pressure. If the blue is transferred to the center of
valve face, contact is satisfactory. If the blue is trans-
ferred to top edge of the valve face, lower valve seat
with a 15 degrees stone. If the blue is transferred to
the bottom edge of valve face raise valve seat with a
65 degrees stone.
(6) Valve seats which are worn or burned can be
reworked, provided that correct angle and seat width
are maintained. The intake valve seat must be ser-
viced when the valve seat width is 2.0 mm (0.079 in.)
or greater. The exhaust valve seat must be serviced
when the valve seat width is 2.5 mm (0.098 in.) or
greater. Otherwise the cylinder head must be
replaced.
(7) When seat is properly positioned the width of
intake and exhaust seats should be 0.75±1.25 mm
(0.030±0.049 in.) (Fig. 122).
(8) Check valve tip to spring seat dimensions A
after grinding the valve seats or faces. Grind valve
tip until within specifications. Measure from valve
tip to spring seat when installed in the head (mea-
surement A) (Fig. 123). For specifications, refer to
Engine Specifications in this section. The valve tip
chamfer may need to be reground to prevent seal
damage when the valve is installed.
CLEANING
Clean all valve guides, valves and valve spring
assemblies thoroughly with suitable cleaning solution
before reassembling.
VALVE INSTALLATION
(1) Coat valve stems with clean engine oil and
insert in cylinder head.
(2) Install new valve stem seals on all valves using
a valve stem seal tool (Fig. 124). The valve stem
seals should be pushed firmly and squarely over
valve guide.CAUTION: If oversize valves are used, there is only
one oversize valve available. The same stem seal is
used on both the standard and oversize valve.
(3) Install valve springs and retainers. Compress
valve springs only enough to install locks, taking
care not to misalign the direction of compression.
Nicked valve stems may result from misalignment of
the valve spring compressor.
CAUTION: When depressing the valve spring
retainers with valve spring compressor the locks
can become dislocated. Check to make sure both
locks are in their correct location after removing
tool.
(4) Check the valve spring installed height after
refacing the valve and seat (measurment B) (Fig.
123). Make sure measurements are taken from top of
spring seat to the bottom surface of spring retainer.
If height is greater than 40.18 mm (1.58 in.), install
Fig. 122 Valve Seat Refacing
Fig. 123 Spring Installed Height and Valve Tip to
Spring Seat Dimensions
1 ± GARTER SPRING
2 ± VALVE SPRING SEAT
3 ± CYLINDER HEAD SURFACE
Fig. 124 Valve Stem Oil Seal Tool
1 ± VALVE SEAL TOOL
2 ± VALVE STEM
9 - 62 2.0L SOHC ENGINEPL
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)

(3) Start the two rear crossmember mounting bolts
into the tapping plates mounted in the body. The
right side bolt can be viewed in the mounting bolt
figure (Fig. 5). The left side bolt is located in the
same location on the other side of the vehicle. Next,
install the two front mounting bolts attaching front
suspension crossmember to frame rails of vehicle.
Lightly tighten all four mounting bolts to a approxi-
mately 2 N´m (20 in. lbs.) to hold the front suspen-
sion crossmember in position.
NOTE: When reinstalling the front suspension
crossmember back in the vehicle, it is very impor-
tant that the crossmember be attached to the body
in exactly the same spot as when it was removed.
Otherwise, the vehicle's wheel alignment settings
(caster and camber) will be lost.
(4) Using a soft face hammer, tap the front suspen-
sion crossmember back-and-forth or side-to-side until
it is aligned with the previously scribed positioning
marks on the body of the vehicle (Fig. 6). Once the
front suspension crossmember is correctly positioned,
tighten the rear two crossmember mounting bolts to
a torque of 203 N´m (150 ft. lbs.), then tighten the
front two crossmember mounting bolts to a torque of
142 N´m (105 ft. lbs.).
(5) Tighten the lower control arm front pivot bolts
to a torque of 163 N´m (120 ft. lbs.).
(6) Attach the steering gear to the front suspen-
sion crossmember (Fig. 4). Install the four power
steering gear mounting bolts. Tighten the mounting
bolts to a torque of 61 N´m (45 ft. lbs.).
(7) Remove the wire or cord suspending the power
steering gear to the underbody.
(8) If the vehicle is equipped with a power steering
fluid cooler, install the two screws securing the cooler
to the front suspension crossmember. They are
located behind the cooler.
(9)
Install each ball joint stud into the steering
knuckle aligning the bolt hole in the knuckle boss with
the notch formed in the side of the ball joint stud.
(10) Install a new ball joint stud pinch bolt and
nut (Fig. 2). Tighten the nut to a torque of 95 N´m
(70 ft. lbs.).
(11) Fasten the engine torque strut to the right
forward corner of the front suspension crossmember
using its mounting bolt (Fig. 5). Follow the procedure
described in the ENGINE service manual group to
properly align and tighten the torque strut and it's
mounting bolts.
NOTE: Before installing the stabilizer bar, make
sure the bar is not upside-down. The stabilizer bar
must be installed with the curve on the outboard
ends of the bar facing downward to clear the con-
trol arms once fully installed (Fig. 7).(12)
First, place the stabilizer bar in position on the
front suspension crossmember. The slits in each cush-
ion must point toward the front of the vehicle and sit
directly on top of the raised beads formed into the
stamping on the crossmember. Next, install the cush-
ion retainers, matching the raised beads formed into
the cushion retainers to the grooves formed into the
cushions. Install the cushion retainer bolts, but do not
completely tighten them at this time.
(13) Install both stabilizer bar links back on vehi-
cle (Fig. 1). Start each stabilizer bar link bolt with
bushing from the bottom, through the stabilizer bar,
inner link bushings, lower control arm, and into the
upper retainer/nut and bushing. Do not fully tighten
the link assemblies at this time.
(14) Install the tire and wheel assemblies back on
vehicle. Tighten the wheel mounting nuts to 135 N´m
(100 ft. lbs.) torque.
(15) Lower the vehicle.
NOTE: It may be necessary to put the vehicle on a
platform hoist or alignment rack to gain access to
the stabilizer bar mounting bolts with the vehicle at
curb height.
(16) Tighten each stabilizer bar link by holding the
upper retainer/nut with a wrench and turning the
link bolt. Tighten each link bolt to a torque of 23
N´m (200 in. lbs.).
(17) Tighten the stabilizer bar cushion retainer
bolts to a torque of 34 N´m (300 in. lbs.).
(18) Check the front wheel alignment on the vehi-
cle. Refer to WHEEL ALIGNMENT in the SUSPEN-
SION service manual group.
Fig. 7 Downward Curve
1 ± STABILIZER BAR
2 ± LINK
3 ± DOWNWARD CURVE
4 ± CUSHION RETAINER
13 - 8 FRAME AND BUMPERSPL
REMOVAL AND INSTALLATION (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)

(4) Tighten the locknut using Special Tool 6856 to
55 N´m (40.5 ft. lbs.) (Fig. 15).
CAUTION: Over tightening the pump lock ring may
result in a leak.
(5) Install fuel tank, refer to the Fuel Tank remov-
al/installation section.
(6) Lower vehicle.
(7) Fill fuel tank. Check for leaks.
FUEL FILTER / PRESSURE REGULATOR
REMOVAL
WARNING: THE FUEL SYSTEM IS UNDER A CON-
STANT PRESSURE, EVEN WITH ENGINE OFF.
BEFORE SERVICING THE FUEL FILTER/FUEL
PRESSURE REGULATOR, THE FUEL SYSTEM
PRESSURE MUST BE RELEASED.
(1) Refer to Fuel System Pressure Release in the
Fuel Delivery System section of this group.
The fuel filter/fuel pressure regulator is located on
the top of fuel pump module. Fuel pump module
removal is not necessary.
(2) Raise vehicle on hoist.
(3) Disconnect fuel supply line at the Filter/Regu-
lator nipple (refer to Quick Connect Fittings in this
section).
(4) Depress locking spring tab on side of Fuel/Reg-
ulator (Fig. 16) and rotate 90É counter-clockwise and
pull out.
NOTE: Make sure that the upper and lower O-rings
are on the Filter/Regulator assembly.
INSTALLATION
Lightly lubricate the O-rings with engine oil.
(1) Insert Filter/Regulator into the opening in the
fuel pump module, align the two hold down tabs with
the flange.
(2) While applying downward pressure, rotate the
Filter/Regulator clockwise until the the spring tab
engages the locating slot (Fig. 17).
(3) Connect the fuel line to the Filter/Regulator.
(4) Lower vehicle from hoist.
Fig. 15 Fuel Tank Locknut
1 ± SPECIAL TOOL 6856
2 ± LOCKNUT
Fig. 16 Locking Spring Tab
1 ± FUEL FILTER/PRESSURE REGULATOR
2 ± SPRING TAB
3 ± LOCATING SLOT
Fig. 17 Spring Tab In Locating Slot
1 ± FUEL FILTER/PRESSURE REGULATOR
2 ± SPRING TAB
3 ± LOCATING SLOT
PLFUEL SYSTEM 14 - 13
REMOVAL AND INSTALLATION (Continued)

1 second. Therefore, battery voltage is not supplied to
the fuel pump, ignition coil, fuel injectors and heated
oxygen sensors.
ENGINE START-UP MODE
This is an OPEN LOOP mode. If the vehicle is in
park or neutral (automatic transaxles) or the clutch
pedal is depressed (manual transaxles) the ignition
switch energizes the starter relay. The following
actions occur when the starter motor is engaged.
²If the PCM receives the camshaft position sensor
and crankshaft position sensor signals, it energizes
the Auto Shutdown (ASD) relay and fuel pump relay.
If the PCM does not receive both signals within
approximately one second, it will not energize the
ASD relay and fuel pump relay. The ASD and fuel
pump relays supply battery voltage to the fuel pump,
fuel injectors, ignition coil and heated oxygen sen-
sors.
²The PCM energizes the injectors (on the 69É
degree falling edge) for a calculated pulse width until
it determines crankshaft position from the camshaft
position sensor and crankshaft position sensor sig-
nals. The PCM determines crankshaft position within
1 engine revolution.
²After determining crankshaft position, the PCM
begins energizing the injectors in sequence. It adjusts
injector pulse width and controls injector synchroni-
zation by turning the individual ground paths to the
injectors On and Off.
²When the engine idles within664 RPM of its
target RPM, the PCM compares current MAP sensor
value with the atmospheric pressure value received
during the Ignition Switch On (zero RPM) mode. If
the PCM does not detect a minimum difference
between the two values, it sets a MAP diagnostic
trouble code into memory.
Once the ASD and fuel pump relays have been
energized, the PCM determines injector pulse width
based on the following:
²Battery voltage
²Engine coolant temperature
²Engine RPM
²Intake air temperature (IAT)
²Throttle position
²The number of engine revolutions since cranking
was initiated.
During Start-up the PCM maintains ignition tim-
ing at 9É BTDC.
ENGINE WARM-UP MODE
This is an OPEN LOOP mode. The following inputs
are received by the PCM:
²Engine coolant temperature
²Manifold Absolute Pressure (MAP)
²Intake air temperature (IAT)²Crankshaft position (engine speed)
²Camshaft position
²Knock sensor
²Throttle position
²A/C switch
²Battery voltage
²Power steering pressure switch
²Vehicle speed
²Speed control
²O2 sensors
²All diagnostics
The PCM adjusts injector pulse width and controls
injector synchronization by turning the individual
ground paths to the injectors On and Off.
The PCM adjusts ignition timing and engine idle
speed. Engine idle speed is adjusted through the idle
air control motor.
CRUISE OR IDLE MODE
When the engine is at operating temperature this
is a CLOSED LOOP mode. During cruising or idle
the following inputs are received by the PCM:
²Intake air temperature
²Engine coolant temperature
²Manifold absolute pressure
²Crankshaft position (engine speed)
²Camshaft position
²Knock sensor
²Throttle position
²Exhaust gas oxygen content
²A/C control positions
²Power steering pressure switch
²Battery voltage
²Vehicle speed
The PCM adjusts injector pulse width and controls
injector synchronization by turning the individual
ground paths to the injectors On and Off.
The PCM adjusts engine idle speed and ignition
timing. The PCM adjusts the air/fuel ratio according
to the oxygen content in the exhaust gas (measured
by the upstream and downstream heated oxygen sen-
sor).
The PCM monitors for engine misfire. During
active misfire and depending on the severity, the
PCM either continuously illuminates or flashes the
malfunction indicator lamp (Check Engine light on
instrument panel). Also, the PCM stores an engine
misfire DTC in memory.
The PCM performs several diagnostic routines.
They include:
²Oxygen sensor monitor
²Downstream heated oxygen sensor diagnostics
during open loop operation (except for shorted)
²Fuel system monitor
²EGR monitor
²Purge system monitor
PLFUEL SYSTEM 14 - 23
DESCRIPTION AND OPERATION (Continued)