coolant temperature CHEVROLET DYNASTY 1993 Owners Manual

(4) Verify vacuum connection at Purge Solenoid is
secure and not leaking (Fig. 3).
(5) Verify the electrical connector is attached to
the MAP sensor (Fig. 4). (6) Check MAP sensor hose at MAP Sensor Assem-
bly (Fig. 4), and at Vacuum Connection at Intake
Plenum Fitting.
(7) Check generator wiring connections. Ensure
the accessory drive belt has proper tension. (8) Verify hoses are securely attached to the vapor
canister (Fig. 5). (9) Verify the engine ground strap is attached at
the engine and dash panel (Fig. 6). (10) Ensure the heated oxygen sensor connector is
connected to the harness connector (Fig. 6). (11) Verify the distributor connector is connected
to the harness connector (Fig. 7). (12) Verify the coolant temperature sensor connec-
tor is connected to the harness connector (Fig. 8). (13) Check vacuum hose connection at fuel pres-
sure regulator and intake plenum connector (Fig. 8).
Fig. 3 Duty Cycle EVAP Canister Purge Solenoid
Fig. 4 Map Sensor Electrical and Vacuum Connections
Fig. 5 Vapor Canister
Fig. 6 Oxygen Sensor Connector
Fig. 7 Distributor Connector
14 - 126 FUEL SYSTEMS Ä

(14) Ensure the harness connector is securely at-
tached to each fuel injector. (15) Check the oil pressure sending unit electrical
connection (Fig. 9).
(16) Check hose connections at throttle body (Fig.
10). (17) Check throttle body electrical connections
(Fig. 10). (18) Check PCV hose connections (Fig. 11).
(19) If equipped, check EGR system vacuum hose
connections (Fig. 12). (20) If equipped, check EGR tube to intake plenum
connections (Fig. 12). (21) Inspect the electronic EGR transducer sole-
noid electrical connector. (22) Ensure the vacuum connections at the elec-
tronic EGR transducer is secure and not leaking.
Fig. 8 Coolant Temperature Sensor and Vacuum Connections
Fig. 9 Oil Pressure Sending Unit ElectricalConnection
Fig. 10 Throttle Body Electrical and Vacuum Hose Connections
Fig. 11 Positive Crankcase Ventilation (PCV) System
Fig. 12 EGR System Vacuum Hose Connections
Ä FUEL SYSTEMS 14 - 127

SYSTEM TESTS
WARNING: APPLY PARKING BRAKE AND/OR BLOCK
WHEELS BEFORE PERFORMING ANY TEST ON AN
OPERATING ENGINE.
OBTAINING DIAGNOSTIC TROUBLE CODES
(1) Connect DRBII scan tool to the data link connec-
tor located in the engine compartment near the pow-
ertrain control module (PCM). (2) Start the engine if possible, cycle the transaxle
selector and the A/Cswitch if applicable. Shut off the
engine. (3) Turn the ignition switch on, access Read Fault
Screen. Record all the fault messages shown on the
DRBII scan tool. Observe the malfunction indicator
lamp (Check Engine lamp on the instrument panel).
The lamp should light for 3 seconds then go out (bulb
check). Diagnostic trouble code erasure; access erase
diagnostic trouble code data
STATE DISPLAY TEST MODE
The switch inputs used by the powertrain control
module (PCM) have only two recognized states, HIGH
and LOW. For this reason, the PCM cannot recognize
the difference between a selected switch position ver-
sus an open circuit, a short circuit, or a defective
switch. If the change is displayed, it can be assumed
that the entire switch circuit to the PCM is functional.
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. Access
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. Park/Neutral Switch
Speed Control Resume
Brake Switch
Speed Control On/Off
Speed Control Set
A/C Switch Sense
S/C Vent Solenoid
S/C Vacuum Solenoid
A/C Clutch Relay
EGR Solenoid
Auto Shutdown Relay
Radiator Fan Relay
Purge Solenoid
Torque Converter Clutch Solenoid
Malfunction Indicator Lamp (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. Battery Temperature
Oxygen Sensor Signal
Engine Coolant Temperature
Engine Coolant Temp Sensor
Throttle Position
Minimum Throttle
Battery Voltage
MAP Sensor Reading
Idle Air Control Motor Position
Adaptive Fuel Factor
Barometric Pressure
Min Airflow Idle Speed
Engine Speed
Fault #1 Key-On Info
Module Spark Advance
Speed Control Target
Fault #2 Key-on Info
Fault #3 Key-on Info
Speed Control Status
Speed Control Switch Voltage
Charging System Goal
Theft Alarm Status
Map Sensor Voltage
Vehicle Speed
Oxygen Sensor State
MAP Gauge Reading
Throttle Opening (percentage)
Total Spark Advance
CIRCUIT ACTUATION TEST MODE
The circuit actuation test mode checks for proper
operation of output circuits or devices which the pow-
ertrain control module (PCM) cannot internally rec-
ognize. The PCM can attempt to activate these
outputs and allow an observer to verify proper oper-
ation. Most of the tests provide an audible or visual
indication of device operation (click of relay contacts,
spray fuel, etc.). Except for intermittent conditions, if
a device functions properly during testing, assume
the device, its associated wiring, and driver circuit
working correctly.
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. Stop All Tests
Ignition Coil #1
Fuel Injector #1
Fuel Injector #2
Fuel Injector #3
14 - 134 FUEL SYSTEMS Ä

Fuel Injector #4
Fuel Injector #5
Fuel Injector #6
Idle Air Control Motor Open/Close
Radiator Fan Relay
A/C Clutch Relay
Auto Shutdown Relay
Purge Solenoid
S/C Serv Solenoids
Generator Field
Tachometer Output
Torque Converter Clutch Solenoid
EGR Solenoid
All Solenoids/Relays
ASD Fuel System Test
Speed Control Vacuum Solenoid
Speed Control Vent Solenoid
THROTTLE BODY MINIMUM AIR FLOW CHECK
PROCEDURE
(1) Warm engine in Park or Neutral until the cool-
ing fan has cycled on and off at least once. (2) Ensure that all accessories are off.
(3) Hook-up the timing check device and tachome-
ter. (4) Disconnect the coolant temperature sensor and
set basic timing to 12É BTDC 62É BTDC.
(5) Shut off engine. Reconnect coolant temperature
sensor wire. (6) Disconnect the PCV valve hose from the PCV
valve (Fig. 4). (7) Plug the PCV valve nipple.
(8) Disconnect the idle purge hose from the vac-
uum tube under the intake manifold (Fig. 5). (9) Install Air Metering Fitting #6457 (0.125 inch
orifice) in the intake manifold mounted idle purge
hose (Fig. 6). (10) Connect DRBII scan tool.
(11) Restart the engine, allow engine to idle for at
least one minute. (12) Using the DRBII scan tool, access Min. Air-
flow Idle Speed. (13) The following will then occur:
² Idle Air Control Motor will fully close.
² Idle spark advance will become fixed.
² Engine RPM will be displayed on DRBII scan tool
(14) Check idle RPM with tachometer, if idle RPM
is within the below specification then the throttle
body min. air flow is set correctly.
(15) If idle RPM is not within specifications, shut
off the engine and clean the throttle body as follows: (a) Remove the throttle body from engine.
Fig. 4 3.0L PCV Valve
Fig. 5 3.0L Idle Purge Hose
Fig. 6 Air Metering Fitting, Special Tool 6457
IDLE SPECIFICATIONS
Ä FUEL SYSTEMS 14 - 135

(6) Remove vacuum hose harness from throttle
body (Fig. 6). (7) Remove vacuum hoses from air intake plenum
(Fig. 6).
(8) If equipped with EGR, remove the EGR tube
flange from intake plenum (Fig. 7). (9) Remove the wiring connector from the coolant
temperature sensor (Fig. 8). (10) Remove vacuum connections from air intake
plenum vacuum connector (Fig. 8). (11) Remove fuel hoses from fuel rail (Fig. 8).
(12) Remove air intake plenum to intake manifold
mounting fasteners (Fig. 9). (13) Remove ignition coil.
(14) Remove air intake plenum (Fig. 10).
(15) Cover intake manifold while servicing injector
fuel rail (Fig. 11). (16) Remove vacuum hoses from fuel rail (Fig. 11).
(17) Disconnect fuel injector wiring harness from
engine wiring harness (Fig. 12). CAUTION: Do not damage the injector O-Rings
when removing the injectors and fuel rail assem-
bly.
Fig. 5 Throttle Cable Attachment
Fig. 6 Electrical and Vacuum Connection to Throttle Body
Fig. 7 EGR Tube to Intake Plenum
Fig. 8 Coolant Temperature Sensor
Fig. 9 Air Intake Plenum to Intake ManifoldAttaching Fasteners
14 - 140 FUEL SYSTEMS Ä

(18) Remove fuel rail mounting bolts. Lift fuel rail
assembly off of intake manifold.
INSTALLATION
(1) Be sure injectors are seated into the receiver
cup with lock ring in place. (2) Make sure the injector holes are clean and all
plugs have been removed. (3) To ease installation, lubricate injector O-ring
with a drop of clean engine oil. (4) Put the tip of each injector into their ports.
Push the assembly into place until the injectors are
seated in the ports. (5) Install fuel rail attaching bolts. Tighten bolts
to 13 N Im (115 in. lbs.) torque.
(6) Install fuel supply and return tube holddown
bolt and the vacuum crossover tube holddown bolt.
Tighten bolts to 10 N Im (95 in. lbs.) torque.
(7) Connect fuel injector wiring harness to engine
wiring harness. (8) Connect vacuum harness to fuel rail assembly.
(9) Remove covering from lower intake manifold
and clean surface. (10) Place intake manifold gaskets with beaded
sealer up on lower manifold. Put air intake in place.
Install ignition coil. Install attaching fasteners and
tighten to 13 N Im (115 in. lbs.) torque.
(11) Connect fuel lines to fuel rail. Tighten hose
clamps to 1 N Im (10 in. lbs.) torque.
(12) Connect vacuum harness to air intake plenum
and fuel pressure regulator. (13) Connect coolant temperature sensor electrical
connector to sensor. (14) Connect EGR tube flange to intake plenum.
Tighten mounting nuts to 22 N Im (200 in. lbs.)
torque. (15) Connect PCV and brake booster supply hose
to intake plenum. (16) Connect idle air control motor and throttle po-
sition sensor (TPS) electrical connectors. (17) Connect vacuum vapor harness to throttle
body. (18) Install throttle cable.
(19) Install air inlet hose assembly.
(20) Connect negative cable to battery.
CAUTION: When using the ASD Fuel System Test,
the Auto Shutdown (ASD) Relay remains energized
for either 7 minutes, until the test is stopped, or un-
til the ignition switch is turned to the Off position. (21) With the ignition key in ON position, access
the DRBII scan tool ASD Fuel System Test to pres-
surize the fuel system. Check for leaks.
FUEL PRESSURE REGULATOR SERVICE
REMOVAL
WARNING: THE 3.0L MPI FUEL SYSTEM IS UNDER
A CONSTANT PRESSURE OF APPROXIMATELY 330
KPA (48 PSI). PERFORM FUEL PRESSURE RE-
LEASE PROCEDURE BEFORE SERVICING THE
FUEL PRESSURE REGULATOR.
(1) Perform the Fuel Pressure Release Procedure.
(2) Disconnect negative cable from battery.
Fig. 10 Removing Air Intake Plenum
Fig. 11 Vacuum Connections at the Fuel Rail
Fig. 12 Fuel Injector Wiring Harness
Ä FUEL SYSTEMS 14 - 141

3.3L AND 3.8L MULTI-PORT FUEL INJECTIONÐSYSTEM OPERATION INDEX
page page
Air Conditioning (A/C) Clutch RelayÐPCM Output. 150
Air Conditioning Switch SenseÐPCM Input .... 147
Auto Shutdown (ASD) Relay and Fuel Pump RelayÐPCM Output .................... 151
Battery VoltageÐPCM Input ............... 147
Brake SwitchÐPCM Input ................. 147
Camshaft Position SensorÐPCM Input ....... 147
Canister Purge SolenoidÐPCM Output ....... 151
CCD Bus .............................. 146
Crankshaft Position SensorÐPCM Input ...... 148
Data Link ConnectorÐPCM Output .......... 152
Electric EGR Transducer (EET) SolenoidÐPCM Output .............................. 152
Engine Coolant Temperature SensorÐPCM Input. 148
Fuel Injectors and Fuel Rail Assembly ........ 155
Fuel InjectorsÐPCM Output ............... 152
Fuel Pressure Regulator .................. 156
Fuel Supply Circuit ...................... 155
General Information ...................... 145
Generator FieldÐPCM Output .............. 150
Heated Oxygen Sensor (O2Sensor)ÐPCM Input. 149
Idle Air Control MotorÐPCM Output ......... 151
Ignition CoilÐPCM Output ................. 153
Malfunction Indicator Lamp (Check Engine Lamp)ÐPCM Output ................... 151
Manifold Absolute Pressure (MAP) SensorÐPCM Input ................................ 149
Modes of Operation ...................... 153
Powertrain Control Module ................. 146
Radiator Fan RelayÐPCM Output ........... 153
Speed Control SolenoidsÐPCM Output ....... 153
Speed ControlÐPCM Input ................ 150
System Diagnosis ....................... 146
TachometerÐPCM Output ................. 153
Throttle Body ........................... 155
Throttle Position Sensor (TPS)ÐPCM Input .... 150
Transaxle Control ModuleÐPCM Output ...... 152
Transaxle Park/Neutral SwitchÐPCM Input .... 150
Vehicle Speed and Distance InputÐPCM Input . 150
GENERAL INFORMATION
3.3L and 3.8L engines use a sequential Multi-port
Electronic Fuel Injection system (Fig. 1). The MPI system is computer regulated and provides precise
air/fuel ratios for all driving conditions.
The MPI system is operated by the powertrain con-
trol module (PCM).
Fig. 1 Multi-Port Fuel Injection Components
Ä FUEL SYSTEMS 14 - 145

The PCM regulates ignition timing, air-fuel ratio,
emission control devices, cooling fan, charging sys-
tem, idle speed and speed control. Various sensors
provide the inputs necessary for the PCM to correctly
operate these systems. In addition 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 in-
take valve in precise metered amounts through elec-
trically operated injectors. The PCM fires the
injectors in a specific sequence. The PCM maintains
an air fuel ratio of 14.7 parts air to 1 part fuel by
constantly adjusting injector pulse width. Injector
pulse width is the length of time the injector is ener-
gized. 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.
SYSTEM DIAGNOSIS
The PCM tests many of its own input and output
circuits. If a fault is found in a major system, the in-
formation is stored in memory. Technicians can dis-
play fault information through the malfunction
indicator lamp (instrument panel Check Engine
lamp) or by connecting the DRBII scan tool. For di-
agnostic trouble code information, refer to the 3.3L/
3.8L Multi-Point Fuel InjectionÐOn-Board
Diagnostics section of this group.
CCD BUS
Various modules exchange information through a
communications port called the CCD Bus. The pow-
ertrain control module (PCM) transmits engine RPM
and vehicle load information on the CCD Bus.
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 en-
gine and vehicle operations through devices that are
referred to as PCM Outputs. PCM Inputs:
² Air Conditioning Controls
² Battery Voltage
² Brake Switch
² Camshaft Position Sensor
² Crankshaft Position Sensor
² Engine Coolant Temperature Sensor
² Manifold Absolute Pressure (MAP) Sensor
² Oxygen Sensor
² SCI Receive ²
Speed Control System Controls
² Throttle Position Sensor
² Transaxle Park/Neutral Switch (automatic tran-
saxle)
² Vehicle Speed Sensor
PCM Outputs:
² Air Conditioning Clutch Relay
² Generator Field
² Idle Air Control Motor
² Auto Shutdown (ASD) and Fuel Pump Relays
² Canister Purge Solenoid
² Malfunction Indicator Lamp (Check Engine Lamp)
² Data Link Connector
² Electronic EGR Transducer
² Fuel Injectors
² Ignition Coil
² Radiator Fan Relay
² Speed Control Solenoids
² Tachometer Output
Based on inputs it receives, the PCM adjusts the
EGR system, fuel injector pulse width, idle speed, ig-
nition spark advance, ignition coil dwell and canister
purge operation. The PCM regulates the cooling fan,
air conditioning and speed control systems. The PCM
changes generator charge rate by adjusting the gen-
erator field. The PCM adjusts injector pulse width (air-fuel ra-
tio) based on the following inputs.
² battery voltage
² engine coolant temperature
² exhaust gas oxygen content (oxygen sensor)
² engine speed (crankshaft position sensor)
² manifold absolute pressure
² throttle position
The PCM adjusts ignition timing based on the fol-
lowing inputs.
² engine coolant temperature
² engine speed (crankshaft position sensor)
² manifold absolute pressure
² throttle position
Fig. 2 PCM
14 - 146 FUEL SYSTEMS Ä

² transaxle gear selection (park/neutral switch)
The PCM also adjusts engine idle speed through
the idle air control motor based on the following in-
puts.
² brake switch
² engine coolant temperature
² engine speed (crankshaft position sensor)
² throttle position
² transaxle gear selection (park/neutral switch)
² vehicle speed
The auto shutdown (ASD) and fuel pump relays are
mounted externally, but turned on and off by the
PCM through the same circuit. The camshaft position sensor and crankshaft posi-
tion sensor signals are sent to the PCM. If the PCM
does not receive both signals within approximately
one second of engine cranking, it deactivates the
ASD and fuel pump relays. When these relays are
deactivated, power is shut off to the fuel injector, ig-
nition coil, oxygen sensor heating element and fuel
pump. The PCM contains a voltage converter that
changes battery voltage to a regulated 8.0 volts. The
8.0 volts power the camshaft position sensor, crank-
shaft position sensor and vehicle speed sensor. The
PCM also provides a 5.0 volts supply for the coolant
temperature sensor, manifold absolute pressure sen-
sor and throttle position sensor.
AIR CONDITIONING SWITCH SENSEÐPCM INPUT
When the air conditioning or defrost switch is put
in the ON position and the low pressure, high pres-
sure and ambient temperature switches are closed,
the PCM receives an input for air conditioning. After
receiving this input, the PCM activates the A/C com-
pressor clutch by grounding the A/C clutch relay.
BATTERY VOLTAGEÐPCM INPUT
The PCM monitors the battery voltage input to de-
termine fuel injector pulse width and generator field
control. If battery voltage is low the PCM will in-
crease injector pulse width.
BRAKE SWITCHÐPCM INPUT
When the brake switch is activated, the PCM re-
ceives an input indicating that the brakes are being
applied. the brake signal cancels speed control and
unlocks the torque convertor. The brake switch is
mounted on the brake pedal support bracket.
CAMSHAFT POSITION SENSORÐPCM INPUT
The camshaft position sensor provides cylinder
identification to the powertrain control module
(PCM) (Fig. 3). The sensor generates pulses as
groups of notches on the camshaft sprocket pass un-
derneath it (Fig. 4). The PCM keeps track of crank-
shaft rotation and identifies each cylinder by the pulses generated by the notches on the camshaft
sprocket. Four crankshaft pulses follow each group of
camshaft pulses.
When the PCM receives two camshaft pulses fol-
lowed by the long flat spot on the camshaft sprocket,
it knows that the crankshaft timing marks for cylin-
der one are next (on driveplate). When the PCM re-
ceives one camshaft pulse after the long flat spot on
the sprocket, cylinder number two crankshaft timing
marks are next. After 3 camshaft pulses, the PCM
knows cylinder four crankshaft timing marks follow.
One camshaft pulse after the three pulses indicates
cylinder five. The two camshaft pulses after cylinder
5 signals cylinder six (Fig. 4). The PCM can synchro-
nize on cylinders 1 or 4.
When metal aligns with the sensor, voltage goes
low (less than 0.5 volts). When a notch aligns with
the sensor, voltage spikes high (5.0 volts). As a group
of notches pass under the sensor, the voltage
switches from low (metal) to high (notch) then back
Fig. 3 Camshaft Position Sensor
Fig. 4 Camshaft Sprocket
Ä FUEL SYSTEMS 14 - 147

to low. The number of notches determine the amount of
pulses. If available, an oscilloscope can display the
square wave patterns of each timing events. Top dead center (TDC) does not occur when notches
on the camshaft sprocket pass below the cylinder. TDC
occurs after the camshaft pulse (or pulses) and after
the 4 crankshaft pulses associated with the particular
cylinder. The arrows and cylinder call outs on Figure 4
represent which cylinder the flat spot and notches
identify, they do not indicate TDC position. The camshaft position sensor is mounted to the top of
the timing case cover (Fig. 5). The bottom of the sensor
is positioned above the camshaft sprocket. The dis-
tance between the bottom of sensor and the
camshaft sprocket is critical to the operation of
the system. When servicing the camshaft posi-
tion sensor, refer to the 3.3L and 3.8L Multi-Port
Fuel InjectionÐService Procedures section in
this Group.
ENGINE COOLANT TEMPERATURE SENSORÐPCM
INPUT
The coolant temperature sensor is a variable resistor
with a range of -40ÉF to 265ÉF. The sensor is installed
next to the thermostat housing (Fig. 6). The PCM supplies 5.0 volts to the coolant tempera-
ture sensor. The sensor provides an input voltage to the
PCM. As coolant temperature varies, the sensor resis-
tance changes resulting in a different input voltage to
the PCM. When the engine is cold, the PCM will demand
slightly richer air-fuel mixtures and higher idle speeds
until normal operating temperatures are reached. The coolant sensor is also used for cooling fan control.
CRANKSHAFT POSITION SENSORÐPCM INPUT
The crankshaft position sensor (Fig. 7) senses slots cut
into the transaxle driveplate extension. There ar e a 3 sets
of slots. Each set contains 4 slots, for a total of 12 slots (Fig. 8). Basic timing is determined by the position of the
last slot in each group. Once the PCM senses the last slot,
it determines crankshaft position (which piston will next
be at TDC) from the camshaft position sensor input. The
4 pulses generated by the crankshaft position sensor
represent the 69É, 49É, 29É, and 9É BTDC marks. It may
take the PCM one engine revolution to determine crank-
shaft position during cranking.
The PCM uses the camshaft position sensor to deter-
mine injector sequence. The PCM determines igni-
Fig. 5 Camshaft Position Sensor Location
Fig. 6 Coolant Temperature Sensor
Fig. 7 Crankshaft Position Sensor
Fig. 8 Timing Slots
14 - 148 FUEL SYSTEMS Ä