1993 CHEVROLET DYNASTY abs

IGNITION SWITCH ON (ZERO RPM) MODE When the multi-port fuel injection system is acti-
vated by the ignition switch, the following actions oc-
cur:
² The PCM determines atmospheric air pressure
from the MAP sensor input to determine basic fuel
strategy.
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 (zero rpm), the auto shutdown (ASD)
relay and fuel pump relay are not energized. There-
fore battery voltage is not supplied to the fuel pump,
ignition coil, fuel injectors or oxygen sensor heating
element.
ENGINE START-UP MODE
This is an OPEN LOOP mode. The following ac-
tions occur when the starter motor is engaged. If the PCM receives the camshaft position sensor
and crankshaft position sensor signals, it energizes
the auto shutdown (ASD) relay and fuel pump relay.
These relays supply battery voltage to the fuel pump,
fuel injectors, ignition coil, and oxygen sensor heat-
ing element. If the PCM does not receive the cam-
shaft position sensor and crankshaft position sensor
signals within approximately one second, it de-ener-
gizes the ASD relay and fuel pump relay. The PCM energizes all six injectors until it deter-
mines crankshaft position from the camshaft position
sensor and crankshaft position sensor signals. The
PCM determines crankshaft position within 1 engine
revolution. After determining crankshaft position, the PCM
begins energizing the injectors in sequence. The PCM
adjusts injector pulse width and controls injector syn-
chronization by turning the individual ground paths
to the injectors On and Off. When the engine idles within 664 RPM of its tar-
get 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 be-
tween the two values, it sets a MAP fault into mem-
ory. Once the ASD and fuel pump relays have been en-
ergized, the PCM:
² Determines injector pulse width based on battery
voltage, coolant temperature, engine rpm and the
number of engine revolutions since cranking was ini-
tiated.
ENGINE WARM-UP MODE This is a OPEN LOOP mode. The following inputs
are received by the PCM:
² engine coolant temperature ²
manifold absolute pressure (MAP)
² engine speed (crankshaft position sensor)
² throttle position
² A/C switch
² battery voltage
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 speed the
following inputs are received by the PCM:
² engine coolant temperature
² manifold absolute pressure
² engine speed (crankshaft position sensor)
² throttle position
² exhaust gas oxygen content
² A/C control positions
² battery voltage
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.
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 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 throttle position sensor (TPS) when it senses an
abrupt decrease in manifold pressure. This indicates
a hard deceleration. The PCM will reduce injector
pulse width. This helps maintain better control of the
air-fuel mixture (as sensed through the O
2sensor).
During a closed throttle deceleration condition, the
PCM grounds the exhaust gas recirculation (EGR)
solenoid. When the solenoid is grounded, EGR func-
tion stops.
14 - 154 FUEL SYSTEMS Ä

WIDE OPEN THROTTLE MODE This is an OPEN LOOP mode. During wide-open-
throttle operation, the following inputs are received
by the PCM:
² battery voltage
² engine coolant temperature
² manifold absolute pressure
² engine speed
² throttle position
When the PCM senses wide open throttle condition
through the throttle position sensor (TPS) it will:
² De-energize the air conditioning relay. This dis-
ables the air conditioning system.
² Provide a ground for the electrical EGR transducer
(EET) solenoid. When the PCM grounds the solenoid,
the EGR system stops operating. The exhaust gas oxygen content input is not ac-
cepted by the PCM during wide open throttle opera-
tion. The PCM will adjust injector pulse width to
supply a predetermined amount of additional fuel.
IGNITION SWITCH OFF MODE When the ignition switch is turned to the OFF po-
sition, the following occurs:
² All outputs are turned off.
² No inputs are monitored.
² The PCM shuts down.
THROTTLE BODY
The throttle body assembly is located on the left
side of the intake manifold plenum (Fig. 19). The
throttle body houses the throttle position sensor and
the idle air control motor. Air flow through the throt- tle body is controlled by a cable operated throttle
blade located in the base of the throttle body.
FUEL SUPPLY CIRCUIT
Fuel is pumped to the fuel rail by an electrical
pump in the fuel tank. The pump inlet is fitted with
a strainer to prevent water and other contaminants
from entering the fuel supply circuit. Fuel pressure is controlled to a preset level above
intake manifold pressure by a pressure regulator.
The regulator is mounted on the fuel rail. The regu-
lator uses intake manifold pressure as a reference.
FUEL INJECTORS AND FUEL RAIL ASSEMBLY
Six fuel injectors are retained in the fuel rail by
lock rings (Fig. 20). The rail and injector assembly is
installed in position with the injectors inserted in re-
cessed holes in the intake manifold.
Fig. 19 Throttle Body
Fig. 20 Fuel Rail Assembly
Ä FUEL SYSTEMS 14 - 155

(18) Inspect the park/neutral switch wiring connec-
tion for damage. Ensure the automatic transaxle
electrical connections are not damaged (Fig. 10). (19) Check the Vacuum Hose Harness connections
at the Intake Plenum (Fig. 11).
(20) Inspect the PCV system connections for dam-
age (Fig. 12). (21) Inspect the crankshaft position sensor electri-
cal connector for damage (Fig. 13). (22) Ensure the vehicle speed sensor electrical con-
nector is attached to the sensor and not damaged
(Fig. 13). (23) Verify the manifold absolute pressure (map)
sensor electrical connector is attached to the sensor
and not damaged (Fig. 14). (24) Verify the engine ground strap is attached at
the engine (below the MAP sensor) and dash panel
(Fig. 14). Inspect the strap for corrosion or damage.
Fig. 10 Automatic Transaxle Electrical Connections
Fig. 11 Vacuum Hose Connections
Fig. 7 Canister Purge Solenoid
Fig. 8 Vapor Canister
Fig. 9 Throttle Body Electrical and Vacuum Connections
Ä FUEL SYSTEMS 14 - 159

3.3L AND 3.8L MULTI-PORT FUEL INJECTIONÐSERVICE PROCEDURES INDEX
page page
Camshaft Position Sensor Service ........... 176
Crankshaft Position Sensor ................ 176
EVAP Canister Purge Solenoid Service ....... 175
Fuel Injector ........................... 174
Fuel Injector Rail Assembly ................ 170
Fuel Pressure Regulator .................. 173
Fuel System Pressure Release Procedure ..... 169 Heated Oxygen Sensor (O
2Sensor) Service . . . 177
Idle Air Control Motor .................... 170
Manifold Absolute Pressure (MAP) Sensor ..... 175
PCM Service ........................... 175
Throttle Body ........................... 169
Throttle Body Removal ................... 169
Throttle Position Sensor .................. 169
THROTTLE BODY REMOVAL
(1) Disconnect negative battery cable.
(2) Remove the air cleaner to throttle body hose
clamp. Remove the nut holding the air cleaner as-
sembly to the air cleaner bracket. Remove the air
cleaner (Fig. 1). (3) Remove throttle and the speed control cables.
(4) Disconnect electrical connectors from the idle
air control motor and throttle position sensor (TPS). (5) Disconnect vacuum hoses from throttle body.
(6) Remove throttle body to intake manifold at-
taching nuts. (7) Remove throttle body and gasket.
(8) Reverse the above procedure for installation.
THROTTLE BODY
When servicing throttle body components, always
reassemble components with new O-rings and seals
where applicable (Fig. 2). 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.
FUEL SYSTEM PRESSURE RELEASE PROCEDURE
WARNING: THE 3.3L AND 3.8L MPI FUEL SYSTEMS
ARE UNDER A CONSTANT PRESSURE OF AP-
PROXIMATELY 330 KPA (48 PSI). RELEASE FUEL
SYSTEM PRESSURE BEFORE SERVICING THE
FUEL PUMP, FUEL LINES, FUEL FILTER, THROT-
TLE BODY OR FUEL INJECTORS.
(1) Disconnect negative cable from battery.
(2) Remove fuel filler cap.
(3) Remove the protective cap from the fuel pres-
sure test port on the fuel rail (Fig. 3). (4) Place the open end of fuel pressure release
hose, tool number C-4799-1, into an approved gaso-
line container. Connect the other end of hose
C-4799-1 to the fuel pressure test port. Fuel pressure
will bleed off through the hose into the gasoline con-
tainer. Fuel gauge C-4799-A contains hose C-4799-1. (5) Continue fuel system service.
THROTTLE POSITION SENSOR
REMOVAL
(1) Disconnect negative cable from battery.
(2) Remove electrical connector from throttle posi-
tion sensor. (3) Remove throttle position sensor mounting
screws (Fig. 4). (4) Lift throttle position sensor off throttle shaft.
INSTALLATION
(1) Install throttle position sensor on throttle shaft.
Install mounting screws. Tighten screw to 2 N Im (17
in. lbs.) torque. (2) Connect electrical connector to throttle position
sensor. (3) Connect negative cable to battery.Fig. 1 Throttle Body Assembly
Ä FUEL SYSTEMS 14 - 169

(12) Remove the fuel hose quick connect fittings
from the chassis tubes. Refer to Fuel Hoses, Clamps
and Quick Connect Fittings in the Fuel Delivery
Section of this Group. Place a shop towel under the
connections to absorb any fuel spilled. fittings. (13) Remove direct ignition system (DIS) coils and
generator bracket to intake manifold bolt (Fig. 10).
(14) Remove intake mounting manifold bolts and
rotate manifold back over rear valve cover (Fig. 11). (15) Cover intake manifold with suitable cover when
servicing (Fig. 12). (16) Remove vacuum harness connector from Fuel
Pressure Regulator. (17) Remove fuel tube retainer bracket screw and
fuel rail attaching bolts (Fig. 12). Spread the retainer
bracket to allow fuel tube removal clearance.
(18) Remove fuel rail injector wiring clip from the
generator bracket (Fig. 13). (19) Disconnect camshaft position sensor, coolant
temperature sensor, and engine temperature sensors
(Fig. 13). (20) Remove fuel rail. Be careful not to damage
the injector O-rings upon removal from their ports
(Fig. 14).
INSTALLATION
(1) Ensure injector holes are clean. Replace
O-rings if damaged. (2) Lubricate injector O-rings with a drop of clean
engine oil to ease installation. (3) Put the tip of each injector into their ports.
Push the assembly into place until the injectors are
seated in the ports (Fig. 14). (4) Install the fuel rail mounting bolts. Tighten
bolts to 22 N Im (200 in. lbs.) torque (Fig. 12).
Fig. 11 Intake Manifold Bolts
Fig. 12 Fuel Rail Attaching Bolts
Fig. 9 MAP Sensor Electrical Connector
Fig. 10 Ignition Coils
14 - 172 FUEL SYSTEMS Ä

WARNING: PLACE A SHOP TOWEL UNDER FUEL
PRESSURE REGULATOR TO ABSORB ANY FUEL
SPILLAGE.
(5) Remove fuel pressure regulator and O-rings
(Fig. 16).
INSTALLATION
(1) Ensure fuel pressure regulator has two plastic
spacers (Fig. 16). Place O-rings in the fuel pressure
regulator cavity (Fig. 17). Do not install O-rings on
the fuel pressure regulator. (2) Insert fuel pressure regulator into the fuel rail.
(3) Install fuel pressure regulator retainer (Fig.
15). (4) Install retainer screw. Tighten to 7 N Im (60 in.
lbs.) torque. (5) Connect vacuum line to the fuel pressure regu-
lator.
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.
(6) 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 INJECTOR
The fuel rail must be removed first. Refer to Fuel
Injector Rail Assembly Removal in this section.
REMOVAL
(1) Disconnect injector wiring connector from injec-
tor. (2) Position fuel rail assembly so that the fuel in-
jectors are easily accessible (Fig. 18).
Fig. 15 Fuel Pressure Regulator
Fig. 16 Fuel Pressure Regulator Removal/Installation
Fig. 17 Fuel Pressure Regulator O-Rings
Fig. 18 Fuel Injector and RailÐTypical
14 - 174 FUEL SYSTEMS Ä

(3) Rotate injector and pull injector out of fuel rail.
The clip will stay on the injector. (4) Check injector O-ring for damage. If O-ring is
damaged, it must be replaced. If injector is reused, a
protective cap must be installed on the injector tip to
prevent damage. Replace the injector clip if it is
damaged. (5) Repeat for remaining injectors.
INSTALLATION
(1) Before installing an injector the rubber O-ring
must be lubricated with a drop of clean engine oil to
aid in installation. (2) Install injector clip by sliding open end into top
slot of the injector. The edge of the receiver cup will
slide into the side slots of clip (Fig. 19). (3) Install injector top end into fuel rail receiver
cap. Be careful not to damage O-ring during instal-
lation (Fig. 19). (4) Repeat steps for remaining injectors.
(5) Connect fuel injector wiring.
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
The alignment of the MAP sensor is critical to the
sensors performance. The top of the sensor is marked
This Side Up (Fig. 20). (1) Disconnect electrical connector from MAP sen-
sor. (2) Remove sensor by unscrewing from the intake
manifold (Fig. 20). (3) Reverse the above procedure for installation.
EVAP CANISTER PURGE SOLENOID SERVICE
(1) Remove vacuum hose and electrical connector
from solenoid (Fig. 21). (2) Depress tab on top of solenoid and slide the so-
lenoid downward out of mounting bracket. (3) Reverse above procedure for installation.
PCM SERVICE
(1) Remove air cleaner duct from PCM.
(2) Remove battery.
(3) Remove PCM mounting screws (Fig. 22).
(4) Remove 60-way electrical connector from PCM.
Fig. 19 Servicing Fuel InjectorÐTypical
Fig. 20 Manifold Absolute Pressure Sensor
Fig. 21 Canister Purge Solenoid
Fig. 22 PCM Removal
Ä FUEL SYSTEMS 14 - 175

(3) Position the steering column assembly in the
vehicle. Align the steering column assembly mounting
bracket slots on the brake pedal bracket attaching
studs (Fig. 13). Install, but loose assemblethe two
upper column bracket, washers and nuts.
(4) Make sure the front wheels are in the straight-
ahead position. Align and assemble the upper steering
coupler to lower steering coupler. Install the upper to
lower steering coupler retaining bolt and nut. Torque
the retaining bolt nut to 28 N Im (250 in. lbs.). Be sure
to install the upper to lower steering coupler
retaining bolt retention pin (Fig. 6). (5) Install the buttons which retain the multi func-
tion switch wiring harness to the steering column.
Connect the multi-function switch wiring harness con-
nector to the multi-function switch. Torque the connec-
tor retaining bolt to 2 N Im (17 in. lbs) usin ga7mm
socket (Fig. 8). (6) Install the upper fixed shroud onto the steering
column assembly. (7) Be sure both breakaway capsules are fully seated
in the slots of the steering column upper support
bracket. Torque the 2 upper steering column assembly
to support bracket nuts to 12 N Im (105 in. lbs.). Torque
the 2 lower steering column assembly to mounting
bracket nuts to 12 N Im (105 in. lbs.).
(8) Complete the wiring harness connections to the
remaining steering column switches (Fig. 9). Install
the lower fixed shroud onto the steering column.
(9) Route the PRNDL actuator assembly under left
steering column wing and along left side of steering
column. Insert the flange of the PRNDL actuator steering
column insert into the steering column jacket (Fig. 7).
Squeeze the legs of the steering column insert together
and install tabs under steering column jacket. Engage
lock bar to secure the actuator assembly into the steering
column jacket (Fig. 7). (10) Hook the PRNDL actuator cable eyelet to the
steering column actuator arm (Fig. 7). Move the shift
lever to neutral, check pointer location, should indicate neutral. If pointer does not indicate neutral adjust actua-
tor with tool (Fig. 14) to center pointer on N (Neutral) and
then check pointer location in other gears.
(11) Install the lock housing shrouds. The shroud
fasteners are Torx-headscrews. Install the tilt lever
(if equipped). (12) Install the lower dash panel cover.
(13) For steering wheel installation with speed con-
trol refer to Group 8 Electrical. For non-speed control,
place the steering wheel on the steering column shaft
with the master splines aligned. Install the steering
wheel to column shaft retaining nut. Tighten retaining
nut to 61 N Im (45 ft. lbs.) torque. Do not force the
steering wheel onto the column shaft by driving
it on with a heavy object. Pull steering wheel
down onto column shaft using ONLY the steering
wheel retaining nut.
(14) For vehicles equipped with a column shift. Pass
the transmission shift cable through its mounting bracket
on the steering column assembly. Connect the transmis-
sion shift cable to the shift lever on the steering column
assembly. Install the shift cable to mounting bracket
retaining clip (Fig. 2). The grommet must be installed
in the shift lever (Fig. 11) before the cable is in-
serted into the grommet. Use MopartMultipurpose
Lubricant, or an equivalent product, to aid installation of
shift link rod into grommet.
(15) Re-adjust the transmission shift linkage.
Whenever the steering column is loosened or
removed, the shift linkage MUST be adjusted and
tested. Refer to Group 21 Transmission for the shift
linkage adjustment procedure.
Fig. 13 Steering Column Mounting
Fig. 14 PRNDL Actuator Cable Adjustment
Ä STEERING 19 - 33