ignition CHEVROLET DYNASTY 1993 Service Manual
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Page 1803 of 2438
mode, the PCM compensates for the failure of certain
components that send incorrect signals. The PCM
substitutes for the incorrect signals with inputs from
other sensors and by using stored default values.Signals that can trigger the Malfunction Indi-
cator (Check Engine) Lamp.
² An emission system component
² Battery Voltage Input
² Charging system
² Engine Coolant Temperature Sensor
² Manifold Absolute Pressure Sensor
² Methanol Concentration Sensor
² Throttle Position Sensor
The malfunction indicator lamp can also display
diagnostic trouble codes. Cycle the ignition switch on,
off, on, off, on, within five seconds and the PCM
displays any diagnostic trouble codes stored in
memory. Refer to the 2.5L Flexible Fuel Multi-Port
Fuel InjectionÐOn Board Diagnostics section in this
group for diagnostic trouble code descriptions.
RADIATOR FAN RELAYÐPCM OUTPUT
The radiator fan is energized by the PCM through
the radiator fan relay. The PCM grounds the radiator
fan relay when engine coolant reaches a predetermined
temperature. For more information, refer to Group 7,
Cooling Systems. The radiator fan relay is mounted on the drivers side
fender well, next to the strut tower (Fig. 11).
SPEED CONTROL SOLENOIDSÐPCM OUTPUT
The speed control vacuum and vent solenoids are
operated by the PCM. When the PCM supplies a
ground to the vacuum and vent solenoids, the speed
control system opens the throttle blade. When the PCM
supplies a ground only to the vent solenoid, the throttle
blade holds position. When the PCM removes the
ground from both the vacuum and vent solenoids, the
throttle blade closes. The PCM balances the two sole-
noids to maintain the set speed. Refer to Group 8H for
speed control information.
TACHOMETERÐPCM OUTPUT
The PCM supplies engine RPM to the instrument
panel tachometer. Refer to Group 8 for tachometer
information.
TORQUE CONVERTER CLUTCH SOLENOIDÐPCM
OUTPUT
Three-speed automatic transaxles use a torque con-
verter clutch solenoid. The PCM controls the lock-up of
the torque convertor through the solenoid. The tran-
saxle is locked up only in direct drive mode. Refer to
Group 21 for transaxle information.
MODES OF OPERATION
As input signals to the PCM change, the PCM
adjusts its response to the 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 different 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 pro-
gramming. Input from the oxygen (O
2) sensor is not
monitored during Open Loop modes. During CLOSED LOOP modes, the PCM does moni-
tor the oxygen (O
2) sensor input. The input indicates if
the calculated injector pulse width results in the ideal
air-fuel ratio for the current percentage of methanol in
the fuel. By monitoring the exhaust oxygen content
through the O
2sensor, the PCM can fine tune the
injector pulse width to achieve optimum fuel economy
combined with low emissions. The 2.5L flexible fuel multi-port fuel injection system
has the following modes of operation:
² Ignition switch ON - Zero RPM
² Engine start-up
² Engine warm-up
² Cruise (Idle)
² Acceleration
² Deceleration
² Wide Open Throttle
² Ignition switch OFF
The engine start-up (crank), engine warm-up, and
wide open throttle modes are OPEN LOOP modes. The
acceleration, deceleration, and cruise modes, with the
engine at operating temperature are CLOSED
LOOP modes (under most operating conditions).
IGNITION SWITCH ON (ZERO RPM) MODE
When the ignition switch cycles and past the On
position, the fuel injection system activates and the
following actions occur:
² For two seconds at key ON (and during cranking),
the methanol concentration sensor calibrates the PCM.
During the calibration period the sensor sends 4.45
volts to the PCM as a correction factor. After the
calibration period, the methanol concentration sensor
output represents the methanol percentage in the fuel.
² The PCM calculates basic fuel strategy by determin-
ing atmospheric air pressure from the MAP sensor
input.
² The PCM monitors the coolant temperature sensor
and throttle position sensor input. The PCM modifies
fuel strategy based on this input. When the key is in the ON position and the engine is
not running, the auto shutdown (ASD) relay and fuel
pump relay are not energized. Therefore battery volt-
age is not supplied to the fuel pump, ignition coil, fuel
injector or oxygen sensor heating element.
Ä FUEL SYSTEMS 14 - 63
Page 1804 of 2438
ENGINE START-UP MODE
This is an OPEN LOOP mode. The following ac-
tions occur when the starter motor is engaged. The methanol concentration sensor finishes cali-
brating the PCM (takes approximately two seconds).
After the calibration period, the PCM determines the
methanol content of the fuel from the methanol con-
centration sensor input. If the PCM receives a camshaft position sensor
(distributor pick-up) signal it energizes the auto
shutdown (ASD) relay and fuel pump relay. These re-
lays supply battery voltage to the fuel injector, igni-
tion coil and oxygen sensor heating element. If the
PCM does not receive a camshaft position sensor sig-
nal, it de-energizes the ASD and fuel pump relays af-
ter approximately one second. With the engine idling within 664 RPM of the tar-
get RPM, the PCM compares the current MAP value
with the atmospheric pressure value it received dur-
ing the Ignition Switch On (Zero RPM) Mode. If a
minimum difference between the two is not detected,
a MAP sensor fault is set into memory. Once the ASD relay and fuel pump relay have en-
ergized, the PCM:
² Supplies a ground path to each injector. The injec-
tors are pulsed four times per engine revolution in-
stead of the normal two pulses per revolution.
² Determines injector pulse width based on engine
coolant temperature, methanol concentration sensor
input, MAP sensor input, throttle position, and the
number of engine revolutions since cranking was ini-
tiated.
² Monitors the coolant temperature sensor, camshaft
position sensor, MAP sensor, methanol concentration
sensor, and throttle position sensor to determine cor-
rect ignition timing.
ENGINE WARM-UP MODE
This is a OPEN LOOP mode. The following inputs
are received by the PCM:
² Engine coolant temperature
² Engine speed
² Manifold absolute pressure (MAP)
² Methanol percentage in fuel
² Throttle position
² A/C switch
² Battery voltage
The PCM determines the methanol content of the
fuel from the methanol concentration sensor input. The PCM provides a ground path for the injectors
and energizes them in sequence. The PCM precisely
controls injector pulse width by switching the ground
on and off. The PCM regulates engine idle speed by adjusting
the idle air control motor. Also, the PCM adjusts ig-
nition timing.
CRUISE OR IDLE MODE
When the engine is at operating temperature, this
is a CLOSED LOOP mode. During cruising speed the
following inputs are received by the PCM:
² Engine coolant temperature
² Manifold absolute pressure
² Methanol percentage in fuel
² Engine speed
² Throttle position
² Exhaust gas oxygen content
² A/C control positions
² Battery voltage
The PCM determines the methanol content of the
fuel from the methanol concentration sensor input. The PCM provides a ground path for the injectors
to precisely control injector pulse width. The PCM
controls engine idle speed and ignition timing. The
PCM controls the air/fuel ratio according to the oxy-
gen content in the exhaust gas.
ACCELERATION MODE
This is a CLOSED LOOP mode. The PCM recog-
nizes an abrupt increase in throttle position or MAP
pressure 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:
² Engine coolant temperature
² Manifold absolute pressure
² Methanol percentage in fuel
² Engine speed
² Throttle position
² Exhaust gas oxygen content
² A/C control positions
² Battery voltage
The PCM may receive a closed throttle input from
the TPS at the same time it senses an abrupt de-
crease in manifold absolute pressure. This indicates a
hard deceleration. In response, the PCM may modify
the injector firing sequence. Modifying the injector
firing sequence helps maintain better control of the
air-fuel mixture (as sensed through the O
2sensor).
WIDE OPEN THROTTLE MODE
This is an OPEN LOOP mode. During wide open
throttle operation, the following inputs are received
by the PCM:
² Engine coolant temperature
² Manifold absolute pressure
² Methanol percentage in fuel
² Engine speed
² Throttle position
When the PCM senses a wide open throttle condi-
tion, it de-energizes the air conditioning clutch relay.
This disables the air conditioning system.
14 - 64 FUEL SYSTEMS Ä
Page 1805 of 2438
The exhaust gas oxygen content input is not ac-
cepted by the PCM during wide open throttle opera-
tion. The PCM will enrichen the air/fuel ratio to
increase performance and compensate for increased
combustion chamber temperature. The PCM determines the methanol content of the
fuel from the methanol concentration sensor input.
IGNITION SWITCH OFF MODE
This is an OPEN LOOP mode. When the ignition
switch is turned to the OFF position, the following
occurs:
² All outputs are turned off.
² No inputs are monitored.
² The PCM shuts down.
THROTTLE BODY
The throttle body houses the throttle position sen-
sor (TPS) and the idle air control motor (Fig. 15). Air
flow through the throttle body is controlled by a ca-
ble operated throttle blade at the base of the throttle
body.
FUEL SUPPLY CIRCUIT
Fuel is pumped to the fuel rail by an electrical
pump in the fuel tank. A filter, attached to the pump
inlet, prevents water and other contaminants from
entering the fuel supply circuit. The vacuum assisted fuel pressure regulator keeps
fuel pressure at 380 kPa (55 psi). The regulator uses
intake manifold pressure at the vacuum tee as a ref-
erence.
FUEL INJECTORS AND FUEL RAIL ASSEMBLY
Four fuel injectors are retained in the fuel rail by
lock rings (Fig. 16). The fuel injectors and rail bolt in
position with the injectors inserted into recessed
holes in the intake manifold.
FUEL PRESSURE REGULATOR
The pressure regulator is located downstream of
the fuel injector on the fuel rail (Fig. 17). The regu-
lator maintains constant 380 kPa (55 PSI) fuel pres-
sure across the fuel injector tip. The regulator has a spring loaded rubber dia-
phragm that uncovers a fuel return port. When the
fuel pump operates, fuel flows past the injector into
the regulator. Fuel is restricted from flowing any fur-
ther by the blocked return port. When fuel pressure
reaches 380 kPa (55 PSI), it pushes on the dia-
phragm, compresses the spring, and uncovers the
fuel return port. The diaphragm and spring continu-
ally move from an open to closed position keeping
the fuel pressure consistent.
Fig. 15 Throttle Body
Fig. 16 Fuel Supply System
Fig. 17 Fuel Pressure Regulator
Ä FUEL SYSTEMS 14 - 65
Page 1806 of 2438
2.5L FLEXIBLE FUEL MULTI-PORT FUEL INJECTIONÐGENERAL DIAGNOSIS INDEX
page page
Fuel System Diagram ..................... 66 Visual Inspection......................... 66
FUEL SYSTEM DIAGRAM
Refer to the Component Identification portion of
this section for a more complete description of the
components shown in Figure 1.
VISUAL INSPECTION
Perform a visual inspection for loose, disconnected,
or misrouted wires and hoses before diagnosing or
servicing the fuel injection system. A visual check
helps save unnecessary test and diagnostic time. A
thorough visual inspection includes the following
checks: (1) Check Ignition Coil Electrical Connections (Fig.
2). (2) Verify the electrical connector is attached to
the Canister Purge Solenoid (Fig. 3). Check the vac-
uum connections at the solenoid and canister. (3) Verify the electrical connector is attached to
the MAP sensor (Fig. 4). Inspect the MAP sensor
vacuum hose for damage and leaks. (4) Verify generator wiring and belt are correctly
installed and tightened.
Fig. 1 Flexible Fuel MPI Components
Fig. 2 Ignition Coil Electrical Connection
14 - 66 FUEL SYSTEMS Ä
Page 1807 of 2438
(5) Check Ignition Cable Routing and Attachment
(Fig. 5).
(6) Check both electrical connectors at the distrib-
utor. (7) Check radiator fan electrical connector.
(8) Check the engine coolant temperature sensor
electrical connection. Inspect battery ground cable
connection (Fig. 6).
(9) Inspect the engine temperature sensor electri-
cal connection (Fig. 7).
(10) Check power brake booster and speed control
vacuum connections (Fig. 8). (11) Check engine harness to main harness electri-
cal connections. (12) Check park/neutral switch wiring connection
(Fig. 9). (13) Ensure battery connections are clean and
tight. (14) Inspect relay connections (Fig. 10)
(15) Ensure the 60-way connector is fully inserted
into the socket on the PCM (Fig. 11). Make sure the
wires are not stretched or pulled out of the connector.
Fig. 3 EVAP Purge Solenoid
Fig. 4 MAP Sensor
Fig. 5 Ignition Cable Mounting and Attachment
Fig. 6 Engine Coolant Temperature Sensor
Fig. 7 Engine Temperature Sensor Electrical Connection
Ä FUEL SYSTEMS 14 - 67
Page 1810 of 2438
2.5L FLEXIBLE FUEL MULTI-PORT FUEL INJECTIONÐON-BOARD DIAGNOSTICS INDEX
page page
Circuit Actuation Test Mode ................. 72
Diagnostic Trouble Codes ................... 71
General Information ....................... 70
High and Low Limits ....................... 71
Ignition Timing Procedure ................... 73 Monitored Circuits
........................ 70
Non-Monitored Circuits ..................... 70
Powertrain Control Module 60-Way Connector . . . 73
State Display Test Mode .................... 72
Throttle Body Minimum Air Flow Check Procedure.. 73
GENERAL INFORMATION
The powertrain control module (PCM) monitors
many different circuits in the fuel injection system. If
the PCM senses a problem with a monitored circuit
often enough to indicate an actual problem, it stores a
diagnostic trouble code in the PCM's memory. If the
problem is repaired or ceases to exist, the PCM cancels
the diagnostic trouble code after 51 vehicle key on/off
cycles. Certain criteria must be met before the PCM stores a
diagnostic trouble code in memory. The criteria may be
a specific range of engine RPM, engine temperature,
and/or input voltage to the PCM. The PCM might not store a diagnostic trouble code
for a monitored circuit even though a malfunction has
occurred. This may happen because one of the diagnos-
tic trouble code criteria for the circuit has not been met.
For example , assume the diagnostic trouble code
criteria for a certain sensor requires the PCM to
monitor the circuit only when the engine operates
between 750 and 2000 RPM. Suppose the sensor's
output circuit shorts to ground when engine operates
above 2400 RPM (resulting in 0 volt input to the PCM).
Because the condition happens at an engine speed
above the maximum threshold (2000 rpm), the PCM
will not store a diagnostic trouble code. There are several operating conditions for which the
PCM monitors and sets diagnostic trouble codes. Refer
to Monitored Circuits and Non-Monitored Circuits in
this section. Technicians can display stored diagnostic trouble
codes by two different methods. The first is to cycle the
ignition switch On - Off - On - Off - On within 5
seconds. Then count the number of times the malfunc-
tion indicator lamp (check engine lamp) on the instru-
ment panel flashes on and off. The number of flashes
represents the trouble code. There is a slight pause
between the flashes representing the first and second
digits of the code. Longer pauses separate individual
trouble codes. The second method of reading diagnostic trouble
codes uses the DRBII scan tool. The DRBII scan tool
connects to the data link (diagnostic) connector in the vehicle (Fig. 1). For diagnostic trouble code informa-
tion, refer to charts in this section.
MONITORED CIRCUITS
The PCM can detect certain fault conditions in the
fuel injection system. Open or Shorted Circuit - The PCM can determine
if the sensor output (input to the PCM) is within proper
range. Also, the PCM can determine open or shorted
circuits. Output Device Current Flow - The PCM senses
whether output devices are hooked up. If a problem
exists within the circuit, the PCM senses whether the
circuit is open, shorted to ground, or shorted high. Heated Oxygen Sensor - Once the system has
entered closed loop, the PCM determines if the oxygen
sensor is switching between rich and lean. Refer to
Modes of Operation in the General Information section
of this group for an explanation of closed loop opera-
tion.
NON-MONITORED CIRCUITS
The PCM does not monitor the following circuits,
systems and conditions that could have malfunctions
causing driveability problems. The PCM might not
store diagnostic trouble codes for these conditions.
However, problems with these systems may cause
Fig. 1 Data Link (Diagnostic) Connector
14 - 70 FUEL SYSTEMS Ä
Page 1811 of 2438
the PCM to store diagnostic trouble codes for other
systems. For example, a fuel pressure problem will not
register a fault directly, but could cause a rich or lean
condition. This could cause the PCM to store an oxygen
sensor diagnostic trouble code. Fuel Pressure - The vacuum assisted fuel pressure
regulator controls fuel system pressure. The PCM
cannot detect a clogged fuel pump inlet filter, clogged
in-line fuel filter, stuck open regulator, or a pinched
fuel supply or return line. However, these could result
in a rich or lean condition causing the PCM to store an
oxygen sensor diagnostic trouble code. Secondary Ignition Circuit - The PCM cannot
detect an inoperative ignition coil, fouled or worn spark
plugs, ignition cross firing, or open spark plug cables. Engine Timing - The PCM cannot detect an incor-
rectly indexed timing belt, camshaft sprocket and
crankshaft sprocket. However, these could result in a
rich or lean condition causing the PCM to store an
oxygen sensor diagnostic trouble code. Cylinder Compression - The PCM cannot detect
uneven, low, or high engine cylinder compression. Exhaust System - The PCM cannot detect a
plugged, restricted or leaking exhaust system. Fuel Injector Mechanical Malfunctions - The
PCM cannot determine if a fuel injector is clogged, the
needle is sticking or if the wrong injector is installed.
However, these could result in a rich or lean condition
causing the PCM to store an oxygen sensor diagnostic
trouble code. Excessive Oil Consumption - Although the PCM
monitors exhaust stream oxygen content when the
system is in closed loop, it cannot determine excessive
oil consumption. Throttle Body Air Flow - The PCM cannot detect a
clogged or restricted air cleaner inlet or filter element. Evaporative System - The PCM cannot detect a
disconnected (open vacuum line) restricted, plugged or
loaded evaporative purge canister. Vacuum Assist - The PCM cannot detect leaks or
restrictions in the vacuum circuits of vacuum assisted
engine control system devices. However, these could
cause the PCM to store a MAP sensor diagnostic
trouble code and cause a high idle condition. PCM System Ground - The PCM cannot determine
a poor system ground. However, one or more diagnostic
trouble codes may be generated as a result of this
condition. PCM Connector Engagement - The PCM may not
be able to determine spread or damaged connector
pins. However, it might store diagnostic trouble codes
as a result of spread connector pins.HIGH AND LOW LIMITS
The PCM compares input signal voltages from each
input device with established high and low limits for the
device. If the input voltage is not within limits and other
criteria are met, the PCM stores a diagnostic trouble code
in memory. Other diagnostic trouble code criteria might
include engine RPM limits or input voltages from other
sensors or switches that must be present before verifying
a diagnostic trouble code condition.
DIAGNOSTIC TROUBLE CODES
A diagnostic trouble code indicates the powertrain
control module (PCM) has recognized an abnormal
condition in the system. Abnormal conditions are usu-
ally shorted or open circuits.
The technician can display diagnostic trouble codes in
two ways. The first way is to cycle the ignition switch and
count the number of times the malfunction indicator lamp
(check engine lamp on the instrument panel) flashes on
and off. The DRBII scan tool provides the second method
of displaying diagnostic trouble codes. Diagnostic trouble
codes indicate the results of a circuit failure, but do not
directly identify the failed component.
For a list of Diagnostic Trouble Codes, refer to
the charts at the end of this section.
OBTAINING DIAGNOSTIC TROUBLE CODES
USING DRBII SCAN TOOL
WARNING: APPLY PARKING BRAKE AND/OR BLOCK
WHEELS BEFORE PERFORMING ANY TEST ON AN
OPERATING ENGINE. (1) Connect DRBII scan tool to the data link (diag-
nostic) connector located in the engine compartment,
next to the PCM (Fig. 1). (2) If possible, start the engine and cycle the A/C
switch if applicable. Shut off the engine. (3)
Turn the ignition switch on, access Read Fault
Screen. Record all the diagnostic trouble codes shown on
the DRBII scan tool. [Observe the malfunction indicator
lamp (check engine lamp) on the instrument panel. The
lamp should light for 2 seconds then go out (bulb check)].
To erase diagnostic trouble codes, use the Erase
Trouble Code data screen on the DRBII scan tool.
USING THE MALFUNCTION INDICATOR LAMP (1) Cycle the ignition key On - Off - On - Off - On
within 5 seconds. (2) Count the number of times the malfunction indi-
cator lamp (check engine lamp on the instrument
panel) flashes on and off. The number of flashes
represents the trouble code. There is a slight pause be-
Ä FUEL SYSTEMS 14 - 71
Page 1812 of 2438
tween the flashes representing the first and second
digits of the code. Longer pauses separate individual
trouble codes.(3) Refer to the Diagnostic Trouble Code Charts at
the end of this group.
STATE DISPLAY TEST MODE
The switch inputs to the powertrain control module
(PCM) have two recognized states; HIGH and LOW.
For this reason, the PCM cannot recognize the differ-
ence between a selected switch position versus an
open circuit, a short circuit, or a defective switch. If
the State Display screen shows the change from
HIGH to LOW or LOW to HIGH, assume the entire
switch circuit to the PCM functions properly. From
the state display screen, access either State Display
Inputs and Outputs or State Display Sensors.
STATE DISPLAY INPUTS AND OUTPUTS
Connect the DRBII scan tool to the vehicle and ac-
cess the State Display screen. Then access Inputs and
Outputs. The following is a list of the engine control
system functions accessible through the Inputs and
Outputs screen.
² Park/Neutral Switch (automatic transaxle only)
² Speed Control Resume
² Speed Control On/Off
² Speed Control Set
² Brake Switch
² A/C Switch Sense
² S/C Vent Solenoid
² S/C Vacuum Solenoid
² A/C Clutch Relay
² Auto Shutdown Relay
² Radiator Fan Relay
² (Duty Cycle) EVAP Purge Solenoid
² Malfunction Indicator (Check Engine) Lamp
STATE DISPLAY SENSORS
Connect the DRBII scan tool to the vehicle and ac-
cess the State Display screen. Then access Sensor
Display. The following is a list of the engine control
system functions accessible through the Sensor Dis-
play screen.
² Oxygen Sensor Signal
² Engine Coolant Temperature
² Engine Coolant Temp Sensor
² Throttle Position
² Minimum Throttle
² Battery Voltage
² MAP Sensor Reading
² Idle Air Control Motor Position
² Adaptive Fuel Factor
² Barometric Pressure
² Min Airflow Idle Spd (Speed)
² Engine Speed
² Fault #1 Key-On Info
² Module Spark Advance ²
Speed Control Target
² Fault #2 Key-on Info
² Fault #3 Key-on Info
² Speed Control Status
² Charging System Goal
² Theft Alarm Status
² Battery Temperature
² Flex Fuel (Methanol Concentration) Sensor Volt-
age
² Methanol Content (percentage)
² Map Sensor Voltage
² Vehicle Speed
² Oxygen Sensor State
² MAP Gauge Reading
² Throttle Opening (percentage)
² Total Spark Advance
CIRCUIT ACTUATION TEST MODE
The Circuit Actuation Test Mode checks for proper
operation of output circuits or devices the powertrain
control module (PCM) cannot internally recognize.
The PCM attempts to activate these outputs and al-
low an observer to verify proper operation. Most of
the tests provide an audible or visual indication of
device operation (click of relay contacts, fuel spray,
etc.). Except for intermittent conditions, if a device
functions properly during testing, assume the device,
its associated wiring, and driver circuit work cor-
rectly.
OBTAINING CIRCUIT ACTUATION TEST
Connect the DRBII scan tool to the vehicle and ac-
cess the Actuators screen. The following is a list of
the engine control system functions accessible
through Actuators screens. Subordinate screens for
each actuator test are also listed. Stop All Tests
Ignition Coil No. 1
Fuel Injector No. 1
Fuel Injector No. 2
Fuel Injector No. 3
Fuel Injector No. 4
Idle Air Control Motor Open/Close
Fuel System
Radiator Fan Relay
A/C Clutch Relay
Auto Shutdown Relay
EVAP Purge Solenoid
Speed Control Servo Solenoids
Generator Field
Tachometer Output
Torque Converter Clutch Solenoid
All Solenoids/Relays
Speed Control Vent Solenoid
Speed Control Vacuum Solenoid
ASD Fuel System Test
14 - 72 FUEL SYSTEMS Ä
Page 1813 of 2438
THROTTLE BODY MINIMUM AIR FLOW CHECK
PROCEDURE
(1) Warm engine in Park or neutral until the cooling
fan has cycled on and off at least once. (2) Hook-up timing check device and Tachometer.
(3) Disconnect the coolant temperature sensor and
set basic timing to 12É BTDC 62É BTDC.
(4) Shut off engine. Connect harness connector to
coolant temperature sensor. (5) Disconnect the PCV valve hose from the nipple
on the intake manifold. (6) Attach Air Metering Fitting #6457 (0.125 in.
orifice) to the intake manifold PCV nipple (Fig. 2).
(7) Connect DRBII scan tool to the data link connec-
tor. The connector is located next to the powertrain
control module (PCM) (Fig. 1). (8) Restart engine. Allow engine to idle for at least
one minute. (9) Using the DRBII scan tool, access Min. Airflow
Idle Spd. The following will then occur:
² idle air control motor fully closes ²
Idle spark advance becomes fixed
² The DRBII scan tool displays engine RPM
(10) Check idle RPM with tachometer, if idle RPM is
within the specifications then the throttle body mini-
mum airflow is set correctly.
If the idle RPM is not within specification, replace
the throttle body. (11) Shut off engine.
(12) Remove Air Metering Fitting #6457 from the
intake manifold PCV nipple. Reinstall the PCV valve
hose. (13) Remove DRBII scan tool.
(14) Disconnect timing light and tachometer.
IGNITION TIMING PROCEDURE
Refer to Group 8D Ignition System.
POWERTRAIN CONTROL MODULE 60-WAY CON-
NECTOR
Check the powertrain control module (PCM) 60-way
connector for the following.
² Spread terminals
² Stretched or pulled out wires
² Undertightened or overtightened 60 way connector
Tighten the PCM connector to 4 N Im (35 in. lbs.)
torque. When checking terminal pin outs, refer to the
Powertrain Control Module 60-Way Connector Dia-
gram for circuit wire colors and cavity numbers.
Fig. 2 Checking Minimum Air Flow Using Special Tool 6457
IDLE SPECIFICATIONS
Ä FUEL SYSTEMS 14 - 73
Page 1817 of 2438
2.5L FLEXIBLE FUEL MULTI-PORT FUEL INJECTIONÐSERVICE PROCEDURES INDEX
page page
Fuel Injector ............................. 80
Fuel Injector Rail Assembly ................. 79
Fuel Pressure Regulator .................... 81
Fuel System Pressure Release Procedure ...... 78
General Information ....................... 77
Heated Oxygen Sensor (O
2Sensor) ........... 82
Identifying Flexible Fuel Components .......... 77
Idle Air Control Motor ...................... 78 Manifold Absolute Pressure (MAP) Sensor
Service ............................... 82
Methanol Concentration Sensor .............. 82
PCM Service ............................ 82
Service Precautions for Flexible Fuel Vehicles .... 77
Throttle Body ............................ 77
Throttle Body Removal ..................... 79
Throttle Position Sensor (TPS) ............... 78
GENERAL INFORMATION
In this model year Chrysler began producing AA-
Body vehicles designed to operate on a mixture of
gasoline and methanol. These automobiles are referred
to as Flexible Fuel vehicles. Fuel system components
designed for use in flexible fuel vehicles are referred to
as Methanol Compatible. Flexible fuel vehicles can operate on a mixture of up
to 85 percent methanol, 15 percent unleaded gasoline.
These vehicles also operate on mixtures containing a
lower percentage of methanol or just pure unleaded
gasoline.
SERVICE PRECAUTIONS FOR FLEXIBLE FUEL
VEHICLES
Methanol is more toxic than gasoline. Always release
fuel system pressure before servicing fuel system com-
ponents and wear methanol resistant gloves and eye
protection. Avoid breathing methanol vapors or ingesting
methanol. Headaches, dizziness and even unconscious-
ness could result from breathing these vapors. Serious
injury, blindness and even death could result from
ingesting methanol. Methanol vapors are extremely flammable and can
travel along the ground. Service vehicles in well ven-
tilated areas and avoid ignition sources. Never smoke
while servicing the vehicle. Do not allow methanol to contact skin. Prolonged
contact with methanol can cause dry skin or an allergic
skin reaction. Also, prolonged contact could result in
absorption through the skin.
IDENTIFYING FLEXIBLE FUEL COMPONENTS
Flexible Fuel vehicles have unique methanol compat-
ible fuel system components. Chrysler identifies methanol
compatible components that could be physically inter-
changed with gasoline only parts by coloring them green
or applying a green label or tag to them. Even though
they may appear physically identical, components
for gasoline only AA-body vehicles must not be used
on flexible fuel vehicles.
FLEXIBLE FUEL COMPONENTS
The fuel system of flexible fuel AA-body vehicles have
the following unique methanol compatible components.
² Duty cycle EVAP purge solenoid
² EVAP canister
² Fuel pump module
² Fuel level sensor
² Fuel gauge (gauge cluster).
² Fuel tank
² Fuel pressure regulator (including O-rings)
² Fuel rail
² Fuel injectors (including O-rings)
² Fuel tubes
² Fuel filter
² Fuel filler cap
² Fuel filler tube
² Methanol concentration sensor
² Pressure relief/rollover valve
² PCV Valve
² All fuel system and emission system hoses and tubes
THROTTLE BODY
WARNING: THROTTLE BODIES DESIGNED FOR
GASOLINE ONLY VEHICLES CANNOT BE USED ON
FLEXIBLE FUEL AA-BODY VEHICLES. WHEN RE-
PLACING THE THROTTLE BODY OF A FLEXIBLE
FUEL VEHICLE, ONLY USE AN ORIGINAL EQUIP-
MENT REPLACEMENT.
When servicing throttle body components, always
reassemble components with new O-rings and seals
where applicable. Never use lubricants on O-rings or
seals, damage may result. If assembly of component is
difficult, use water to aid assembly. Use care when
removing hoses to prevent damage to hose or hose
nipple.
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