Engine Controls - Remove/install/overhaul Buick Roadmaster VIII

INTRODUCTION

Removal, overhaul and installation procedures (when given by manufacturer) are covered in this article. If component removal and installation is primarily an unbolt and bolt-on procedure, only a simple torque specification may be supplied.

BODY CODE IDENTIFICATION

BODY CODE IDENTIFICATION

ELECTRONIC CONTROL MODULE (ECM)

STATIC CHARGE(VOLTS)

Scheme 1

Note. Before replacing ECM, carefully inspect all wiring and control components. Failure to test for short circuits may result in repeated ECM failure due to grounds and Quad-Driver failure. To prevent internal damage to ECM, ensure ignition switch is in OFF position when disconnecting or reconnecting ECM connectors or 12-volt components.

Removal

Ensure ignition switch is in OFF position. Disconnect negative battery cable. Remove electrical connectors from ECM. Remove ECM from vehicle. Remove MEM-CAL or PROM and CAL-PAK (if equipped) from ECM.

Installation

Install PROM and CAL-PAK (if equipped) or MEM-CAL in new ECM. Install ECM into vehicle. Connect electrical connectors to ECM. Install access panels. Reconnect negative battery cable to battery.

Removal & Installation

Some ECM models use a CAL-PAK as well as a PROM. (Scheme 2) If replacing ECM, remove CAL-PAK from old ECM and install in new ECM. Removal and replacement procedures for CAL-PAK are same as for PROM. See PROGRAMMABLE READ-ONLY MEMORY (PROM). If units are improperly installed, grounding diagnostic test lead will set Code 52.

Scheme 2

Disconnect negative battery cable. Remove ECM from vehicle. Using 2 fingers, push retaining clips back from MEM-CAL. At same time, grasp MEM-CAL at both ends and lift out of socket. DO NOT remove MEM-CAL cover.

1. Carefully align MEM-CAL pins with ECM pin holes. DO NOT press in middle of MEM-CAL. Push downward evenly on ends of MEM-CAL until retaining clips on ends of MEM-CAL snap into place.
2. Install ECM. Reconnect negative battery cable. Turn ignition on and ground ALDL connector. Code 12 should flash at least 4 times (if no other codes are present). If Code(s) 42, 43, 51 or 52 is present, or if MALFUNCTION INDICATOR LIGHT (MIL) stays on constantly with code(s) present, MEM-CAL is not fully seated or is defective. If it is necessary to remove MEM-CAL, follow previous removal instructions.

1. Remove ECM from vehicle. See «ELECTRONIC CONTROL MODULE (ECM)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__electronic-control-module-ecm). Position ECM so bottom cover faces upward. Remove slide-off PROM access cover by depressing locking tab.
2. Using PROM removal tool, grasp PROM at narrow ends. Gently rock PROM from end to end while pulling up on PROM. If replacing PROM, remove old PROM from PROM carrier. (Scheme 2)

Note. Note reference notch locations in PROM, carrier and ECM for reassembly reference.

1. Ensure new PROM has same service number as old one. Place new PROM in PROM carrier. Position PROM carrier squarely over ECM PROM socket. Press on PROM carrier until PROM is firmly seated in ECM. NOTE: Ensure reference notches in both ECM and PROM are properly aligned. If PROM is installed backwards, PROM will be destroyed when ignition is turned on.
2. Install PROM access cover on ECM. Install ECM in vehicle. See «ELECTRONIC CONTROL MODULE (ECM)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__electronic-control-module-ecm) . Start engine and ground ALDL diagnostic test connector. Watch for trouble Code 51 or 52.
3. If Code 51 or 52 sets, PROM is either not fully seated in ECM or installed backwards, has bent pins or is defective. If bent pins crack when trying to straighten, replace PROM. If PROM is installed backwards or is defective, replace PROM.

IGNITION MODULE (DIS) (1.9L, 2.0L, 2.2L, 3.1L & 3.4L)

Note. If spark plug boots adhere to spark plugs, use Boot Remover (J-36011). Twist first and then pull upward. Boots must be in place on housing before installing ignition system assembly, or damage may result.

1. Disconnect negative battery cable. Unplug connectors at ignition module. (Scheme 4)- see scheme 6. Disconnect spark plug wires from coil pack. Remove coil pack/ignition module assembly. For ignition module location, see COMPONENT LOCATIONS in I - SYS/COMP TESTS article in this section. Separate ignition coil(s) from ignition module (if possible).
2. To install, reverse removal procedure. Tighten ignition module mounting bolts/nuts. On 1.9L, ensure mounting bolt holes are clean of old sealant. Use new mounting bolts supplied with module. On all models, tighten mounting bolts/nuts to specification. See «TORQUE SPECIFICATIONS»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__torque-specifications).

Scheme 3

Scheme 4

Scheme 5

1. Disconnect negative battery cable. Disconnect 11-pin harness connector. Remove 4 ignition module cover-to-cam carrier bolts.
2. Remove ignition system assembly from engine. Remove 4 housing cover screws. Remove housing cover. Remove coil harness connector from module. Remove module-to-cover screws. Remove module from cover. To install, reverse removal procedure.

Note. DO NOT wipe grease from module or coil if module is not being replaced. If installing a new module, spread silicone grease on metal face of module and on cover where module seats. Grease is included with new module and is necessary for module cooling purposes.

Disconnect negative battery cable. Unplug 14-way connector at ignition module. Disconnect spark plug wires from coil pack. Remove nuts and washers securing ignition module to bracket. Remove coil-to-ignition module Torx screws. Note wire colors for reassembly. Unplug connectors between ignition coil and module. Remove module. To install, reverse removal procedure.

IGNITION MODULE - OPTI-SPARK (5.7L VIN P)

Note. It is not necesasary to remove teh distributor assembly from the vehicle to remove and install module.

1. Remove spark plug wires from distributor cap (noting plug wire routing for installation reference).
2. Loosen cap bolts/screws and remove distributor cap.
3. Remove 2 bolts/screws and lift out ignition control module.
4. Unplug ignition pickup coil leads (noting wire colors for installation reference. Leads cannot be interchanged)
5. Remove module. IMPORTANT: DO NOT remove greast from ignition control module or distributor base if coil is to be reused. If new module is to be installed, spread supplied special grease on metal face of igniton control module and on distributor base where ignition control module seats. Grease is used for ignition control module cooling.

Exploded View Of Distributor Assembly. Scheme 6

1. Install module.
2. Install pickup coil leads to original position as noted during removal.
3. Install module bolts/screws. Tighten to 18 INCH lbs. (2.0 N.m).
4. Install distributor cap. . Tighten bolts/screws to 18 INCH lbs. (2.0 N.m).
5. Install spark plug wires as noted during removal procedure.

Disconnect negative battery cable. Remove camshaft position sensor bolt. Disconnect wiring harness and remove sensor. To install, reverse removal procedure.

1. Remove serpentine belt from crankshaft pulley. Raise vehicle on hoist. Remove right front tire and wheel assembly. Remove right inner fender access cover.
2. Using 28-mm socket, remove crankshaft harmonic balancer bolt. Remove harmonic balancer. Remove foreign object deflector ( DO NOT use pry bar). Disconnect sensor harness connector. Remove sensor and pedestal (as an assembly) from block. Remove sensor from pedestal.

1. Loosely install sensor on pedestal. Position sensor with pedestal attached onto Installer (J-37089). (Scheme 7) Position installer onto crankshaft.
2. Install pedestal-to-block bolts. Tighten bolts to 18-26 ft. lbs. (25-35 N.m). Tighten pedestal pinch bolt to 26-44 INCH lbs. (3-5 N.m). Remove installer. Install foreign object deflector. Place harmonic balancer onto installer. Rotate balancer on installer. If any vanes of interrupter rings contact installer, replace harmonic balancer.
3. Install balancer on crankshaft. To complete installation, reverse removal procedure. Tighten balancer bolt to specification. See «TORQUE SPECIFICATIONS»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__torque-specifications).

Disconnect sensor harness connector. Remove bolt and sensor from engine block. Inspect crankshaft sensor "O" ring for wear, cracks or other damage. Replace as necessary. Lubricate new "O" ring with engine oil before installing. To install, reverse removal procedure.

Disconnect negative battery cable. Remove starter motor. Disconnect sensor harness connector at module. Remove sensor mounting bolt. Remove sensor from engine block. Inspect sensor "O" ring for wear, cracks or other damage. Replace as necessary. Lubricate new "O" ring with engine oil before installing. To install, reverse removal procedure.

1. Disconnect negative battery cable. Remove serpentine belt from crankshaft pulley. Raise and support vehicle.
2. Using an 18-mm socket, remove crankshaft harmonic balancer bolt. Remove harmonic balancer. Disconnect sensor harness connector. Remove sensor bolts. Remove sensor.
3. To install, reverse removal procedure. Tighten harmonic balancer bolt to specification. See «TORQUE SPECIFICATIONS»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__torque-specifications) .

Disconnect negative battery cable. Remove spark plug wires from coil. Remove coil-to-module bolts. Remove coil assembly. To install, reverse removal procedure. Tighten retaining bolts to specification. See TORQUE SPECIFICATIONS .

Disconnect negative battery cable. Remove spark plug wires from coil pack. Remove coil-to-ignition module Torx screws. Tilt coil assembly back. Disconnect module connectors and remove coil pack. To install, reverse removal procedure. Tighten retaining bolts to specification. See TORQUE SPECIFICATIONS .

Disconnect negative battery cable. Remove spark plug wires from coils. Remove nuts or screws attaching ignition coils to ignition module. Remove coils. To install, reverse removal procedure.

1. Disconnect negative battery cable. Disconnect 11-pin harness connector. Remove ignition cover-to-cam carrier bolts. Remove ignition system assembly from engine. Remove housing cover screws. Remove housing cover.
2. Remove coil harness connector from module. Remove module-to-cover screws. Remove module from cover. To install, reverse removal procedures. Tighten screws to specification. See «TORQUE SPECIFICATIONS»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__torque-specifications) .

1. Disconnect negative battery cable. Disconnect harness connector from ECM. Remove ECM from mounting bracket. Remove access cover from ECM. Using thumb and forefinger, squeeze both ends of knock sensor module inward and pull module up from access hole.
2. To install, reverse removal procedure. Ensure module latches into holder in ECM assembly.

Note. Knock sensor module is on bracket located near right hood hinge.

Turn ignition off. Disconnect knock sensor module harness connector. Remove module mounting screws. Remove module. To install, reverse removal procedure.

1. Make sure ignition switch is in the "OFF" position.
2. Remove air cleaner (if necessary).
3. Remove electrical connector(s) from distributor
4. Loosen distirbutor cap bolts/screws. Set aside distributor cap, If plug wires need to be removed, mark wires for installation reference.
5. Note installed position of distributor rotor in relation to engine. Note installed position of distributor housing in relation to engine. Marking rotor installed position, and distributor housing installed position, will help with installation reference.
6. Remove distributor hold down bolt/screw. Remove hold down clamp (if eauipped).
7. Note rotation of distributor rotor as distributor assembly is pulled upward and mark rotor position when it stops rotation.
8. Remove distributor from vehicle.
9. Remove distributor gasket from distributor assembly.

1. Install NEW gasket to distributor assembly.
2. Place distributor in position, with housing pointing toward position first noted during removal, and with rotor pointing to position where it stopped rotating upon removal.
3. Lower distributor into engine. Distributor rotor should rotate to its original position first noted during removal. Install distributor Hold down clamp and bolt/screw. Tighten bolt/screw to 27 ft. lb. (36 N.m).
4. Reinstall distributor cap.
5. If plug wires were removed, reinstall pllug wires as identified during removal.
6. Install distributor electrical connector(s).
7. reinstall air cleaner (if removed).
8. Check ignition timing. See IGNITION TIMING in appropriate ADJUSTMENTS article.

1. Disconnect negative battery cable. Drain cooling system. Disconnect Intake Air Temperature (IAT) sensor harness connector. Remove knock sensor. Remove air intake duct. Remove serpentine belt. Remove coolant hoses to water pump assembly.
2. Disconnect coolant temperature sensor harness connector. Remove 6 water pump-to-engine block mounting bolts. Remove water pump assembly. Remove crankshaft harmonic balancer. Remove belt tensioner. Remove spark plug wires from distributor.
3. Disconnect 4-terminal ECM connector to distributor. Remove 3 distributor mounting bolts. Pull distributor forward until distributor shaft disengages from engine. Mark top surface of distributor shaft for reassembly purposes.
4. To install, ensure mark made on distributor shaft during removal is on top or facing up. To complete installation, reverse removal procedure. Refill coolant and check for leaks. Tighten distributor hold-down bolts to 96 INCH lbs. (11 N.m).

FUEL PRESSURE RELIEF (PFI)

1. Fuel system is under pressure. Relieve pressure before servicing fuel system. Fuel pressure may be relieved using one of 2 different methods.
2. One method is to disconnect fuel pump connector. Start engine and allow to run until it stops. Operate starter for 3 seconds to remove remaining fuel from fuel lines. Reconnect fuel pump once repair is complete.
3. The other method is to install Fuel Pressure Gauge (J-34730-1 or SA9127E for Saturn) on fuel pressure test port. When installing fuel pressure gauge, wrap shop towel around pressure connection to absorb fuel leakage. Place gauge bleed hose in container. Open bleed valve to bleed fuel pressure.

FUEL PRESSURE RELIEF (TBI)

Disconnect negative battery cable. Remove fuel filler cap. Since these TBI units contain an internal bleed-down feature, system fuel pressure should dissipate after a short time.

1. Relieve fuel pressure. See «FUEL PRESSURE RELIEF (PFI)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief-pfi) . Remove air inlet ducts. Disconnect and mark electrical connections and vacuum hoses from throttle body. Disconnect control cables from throttle body.
2. Drain cooling system and remove coolant hoses to throttle body (if applicable). Remove throttle body retaining bolts. Remove throttle body and gasket.

Note. Identification number is stamped on throttle body. Use identification number to order replacement components.

1. To install, reverse removal procedure using new gasket. Tighten retaining bolts to specification. See «TORQUE SPECIFICATIONS»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__torque-specifications) . Refill cooling system, if drained.
2. If installing new Idle Air Control (IAC), ensure IAC pintle length setting is adjusted before installation. See «IDLE AIR CONTROL (IAC) VALVE»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__idle-air-control-iac-valve) . Adjust idle speed and TPS (if removed and if adjustable). See ADJUSTMENTS article in this section.

THROTTLE BODY (TBI)

Note. Ensure residual fuel pressure is relieved before working on throttle body.

1. Relieve fuel pressure. See «FUEL PRESSURE RELIEF (TBI)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief-tbi) . Disconnect negative battery cable. Remove air cleaner and related ducting.
2. Remove electrical connectors from Idle Air Control (IAC), TPS and fuel injector(s). Lay wiring harness aside. Remove throttle cable, return springs, transmission/transaxle cable, and cruise control cable (if equipped). Label and remove vacuum hoses.
3. Remove fuel feed and return lines. Use back-up wrenches to prevent nuts in throttle body from coming loose. Remove fuel line "O" rings and discard. Remove throttle body retaining bolts. Remove TBI unit and base gasket. Discard base gasket.

Disassembly (Throttle Body Cover)

1. Place throttle body on Holding Fixture (J-9789-118 or BT 30-15) to prevent damage to throttle valve. Remove cover-to-throttle body screws, noting location of 2 short screws.
2. Remove throttle body cover. (Scheme 8) Throttle body cover and pressure regulator are serviced as an assembly. DO NOT remove pressure regulator-to-cover screws. Remove TPS and IAC assembly. Throttle valve screws are staked in position and should not be removed.

Scheme 7

Cleaning & Inspection

1. Clean all metal parts in a cold immersion-type cleaner such as Carbon X (X-55). Blow dry using compressed air.
2. DO NOT immerse the following in cleaner solvent: TPS, IAC, throttle body cover, fuel meter and pressure regulator assemblies, fuel injector, fuel filter, rubber parts and diaphragms.
3. Inspect mating surfaces for damage that may prevent gasket sealing. Repair or replace components as necessary.

Reassembly

1. Install NEW dust seal into recess of throttle body. Install fuel outlet passage gasket on cover. Install throttle body cover gasket on throttle body. Install cover. Ensure pressure regulator dust seal and cover gaskets are in place.
2. Apply thread locking compound to cover attaching screws. Install cover screws and lock washers. Tighten screws. Connect electrical lead to fuel injector. Install air cleaner. To complete assembly, reverse disassembly procedure.

Disassembly (Fuel Meter Assembly Saturn)

Remove fuel meter-to-throttle body retaining screws. Remove fuel meter assembly. (Scheme 9) Discard gasket. If fuel pressure regulator cover is removed, replace regulator diaphragm to prevent fuel leaks. Remove TPS and IAC assembly. Throttle valve screws are staked in position and should not be removed.

Scheme 8

1. Clean all metal parts in a cold immersion-type cleaner such as Carbon X (X-55). Blow dry with compressed air.
2. DO NOT immerse the following in cleaner solvent: TPS, IAC, throttle body cover, fuel meter and pressure regulator assemblies, fuel injector, fuel filter, rubber parts and diaphragms.
3. Inspect mating surfaces for damage that may prevent gasket sealing. Repair or replace components as necessary.

1. Install NEW fuel meter-to-throttle body assembly gasket. Match cutout portions of gasket with openings in throttle body assembly.
2. Place fuel meter assembly on throttle body. Install fuel meter-to-throttle body screws and washers (screws should be coated with locking compound). Tighten screws to specification. See «TORQUE SPECIFICATIONS»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__torque-specifications) .
3. Install NEW "O" rings on fuel lines. Using a back-up wrench on fuel line fittings, tighten fuel line nuts. To complete reassembly, reverse disassembly procedure.

Installation (Throttle Body - All Models)

1. Install throttle body unit to intake manifold using NEW gaskets. Tighten retaining bolts to specification. See «TORQUE SPECIFICATIONS»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__torque-specifications) . Install NEW "O" rings onto fuel lines.
2. Connect fuel feed and return lines throttle body. Use a back-up wrench to prevent fuel line fittings in throttle body from turning. Tighten fuel line nuts to specifications. See «TORQUE SPECIFICATIONS»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__torque-specifications) .

FUEL PRESSURE REGULATOR

Note. On TBI models, fuel pressure regulator is integral with fuel meter assembly. See THROTTLE BODY (TBI) .

Removal (1.9L, 2.0L, 2.2L, 2.3L, 3.3L, 3.8L & 4.9L)

1. Relieve fuel pressure. See «FUEL PRESSURE RELIEF (PFI)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief-pfi) . Disconnect pressure regulator-to-fuel rail hose. On 2.3L, remove fuel rail. See «FUEL RAIL & INJECTORS (PFI)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-rail-injectors-pfi) .
2. On all models, remove pressure regulator bolts. Remove pressure regulator from fuel rail. On 2.3L, remove pressure regulator retainer and seal from fuel rail.

To install, reverse removal procedure. DO NOT reuse "O" rings. Lubricate fuel rail seal with oil and install in regulator. Tighten bolts to specification. See TORQUE SPECIFICATIONS .

Note. On 3.4L VIN S models, fuel regulator and fuel rail are serviced as an assembly only. DO NOT remove regulator cover from fuel rail.

Removal (3.1L & 3.4L VIN X)

1. Relieve fuel pressure. See «FUEL PRESSURE RELIEF (PFI)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief-pfi) . Remove upper manifold or intake manifold plenum. On 3.1L models, remove fuel rails. See «FUEL RAIL & INJECTORS (PFI)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-rail-injectors-pfi) .
2. On all models, remove inlet and return fuel fittings and gaskets. Remove pressure regulator-to-bracket retaining bolts. Separate pressure regulator from fuel rail.
3. Remove pressure regulator base-to-fuel rail connector tubes from pressure regulator.

1. To install, reverse removal procedure. Lubricate NEW "O" rings with oil. Install fuel return "O" rings on fuel rails. Fuel return "O" rings are larger in diameter than connector tube "O" rings.
2. Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__torque-specifications) .

Removal (5.7L VIN P)

1. Relieve fuel pressure. Remove fuel rails. See «FUEL PRESSURE RELIEF (PFI)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief-pfi) and «FUEL RAIL & INJECTORS (PFI)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-rail-injectors-pfi) .
2. Remove crossover tube retainer on right fuel rail. remove rear crossover tube retainer at pressure regulator on right fuel rail. Separate fuel rail assemblies.
3. Remove pressure regulator bracket-to-fuel rail bolt. Remove bracket-to-regulator base bolt. Remove bracket. Remove fuel outlet tube-to-fuel rail bolt. Remove base-to-right fuel rail bolt.
4. Remove pressure regulator assembly from fuel rail. Rotate pressure regulator and remove from outlet tube. Remove base-to-fuel rail connector tube. Remove "O" rings from connector tube, outlet tube and crossover tube.

To install, reverse removal procedure. Install NEW "O" rings and lubricate with clean engine oil. Tighten retaining bolts to specification. See TORQUE SPECIFICATIONS .

FUEL RAIL & INJECTORS (PFI)

Removal (1.9L, 2.0L, 3.3L, 3.4L VIN S & 3.8L)

1. Relieve fuel pressure. See «FUEL PRESSURE RELIEF (PFI)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief-pfi). Turn ignition off. Disconnect electrical connectors from injectors. Disconnect and plug hoses to fuel rail.
2. Remove fuel rail retaining bolts. Remove fuel rail from intake manifold using equal force on both sides of fuel rail. Remove injector-to-fuel rail retaining clip (if used). Remove injectors. (Scheme 10)- (Scheme 14).

Note. If injector is replaced, ensure replacement injector has the same part number as that removed.

To install, reverse removal procedure. Coat NEW "O" rings with clean engine oil. Install "O" rings on injectors. Position fuel rail on intake manifold. Push down on rail to seat injectors in manifold. Tighten fuel rail bolts to specification. See TORQUE SPECIFICATIONS .

Scheme 9

Scheme 10

Scheme 11

Scheme 12

Scheme 13

Removal (2.3L)

1. Relieve fuel pressure. See «FUEL PRESSURE RELIEF (PFI)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief-pfi). Remove crankcase ventilation oil/vapor separator.
2. Remove fuel lines from fuel rail. Remove vacuum line at pressure regulator. Disconnect wiring connector while pushing inward on connector. Remove fuel rail retaining bolts. Remove fuel rail. (Scheme 15)
3. Remove injector-to-fuel rail retaining clip. Remove injector from fuel rail. Remove injector "O" rings.

To install reverse removal procedure. Lubricate injector "O" rings with clean engine oil. Install injector-to-fuel rail retaining clip, with open end facing injector electrical connection. Tighten fuel rail retaining bolts.

Scheme 14

Removal (3.1L, 3.4L VIN X & 5.0L)

1. Relieve fuel pressure. See «FUEL PRESSURE RELIEF (PFI)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief-pfi). Disconnect negative battery cable. Remove intake manifold upper plenum. Disconnect and mark vacuum lines. Remove EGR-to-intake manifold retaining bolts. Some models use an EGR pipe which requires removal at EGR base.
2. Remove throttle cable bracket bolts. Disconnect cables and electrical wiring connections from throttle body. Remove throttle body from intake manifold. Remove plenum and gasket. (Scheme 16)- (Scheme 17).
3. Disconnect vacuum hose to pressure regulator. Remove runners. Disconnect fuel lines from fuel rail. With ignition off, disconnect electrical connectors from injectors.
4. Remove fuel rail retaining bolts. Remove fuel rail and injectors. On 5.0L and 5.7L, rotate injector retaining clip to unlock. On all models, remove injectors from fuel rail. Remove "O" rings from injectors.

To install, reverse removal procedure. Coat new "O" rings with clean engine oil. Install "O" rings on injectors. Tighten bolts to specification. See TORQUE SPECIFICATIONS .

Scheme 15

Scheme 16

Removal (4.9L)

1. Remove air cleaner. Relieve fuel pressure. See «FUEL PRESSURE RELIEF (PFI)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief-pfi). Disconnect negative battery cable. Remove power steering pump and set aside.
2. Disconnect vacuum hose to pressure regulator and base assembly. Disconnect accelerator cable, cruise control cable and bracket. Disconnect electrical connectors. Drain coolant and disconnect coolant hose to thermostat housing.
3. Wrap shop towel around fuel line, and disconnect fuel feed line from rear fuel rail assembly and fuel return line. Discard "O" rings. Disconnect EGR vacuum hose. Remove EGR valve. Remove fuel rail attaching bolts. Disconnect electrical connectors at front and rear fuel rail assemblies. Remove fuel rail from intake manifold. (Scheme 18)

To install, reverse removal procedure. Coat new "O" rings with clean engine oil. Install "O" rings on injectors. Tighten bolts to specification. See TORQUE SPECIFICATIONS .

Scheme 17

1. Relieve fuel pressure. See «FUEL PRESSURE RELIEF (PFI)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief-pfi). Disconnect negative battery cable. Remove fuel rail cover (if equipped).
2. Disconnect quick-connect fitting at fuel rail feed and return pipes. Disconnect vacuum hoses and injector electrical harness connectors. Remove fuel rail bolts. Remove fuel rail assembly from manifold. Remove fuel injectors from fuel rail. (Scheme 19)

To install, reverse removal procedure. Coat new "O" rings with clean engine oil. Install "O" rings on injectors. Tighten bolts to specification. See TORQUE SPECIFICATIONS .

Scheme 18

1. Relieve fuel pressure. See «FUEL PRESSURE RELIEF (TBI)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief-tbi). Remove throttle body cover, leaving cover gasket in place. Using screwdriver and fulcrum, carefully pry injector out. see scheme 21 Remove small "O" ring from nozzle end of injector.
2. Carefully rotate injector fuel filter back and forth to remove fuel filter from base of injector. Remove and discard throttle body cover gasket. Remove large "O" ring and steel back-up washer from top counterbore of throttle body injector cavity.

Scheme 19

1. Install fuel filter on nozzle end of fuel injector. Ensure large end of filter faces injector so filter covers the raised rib at base of injector. Lubricate small "O" ring with clean engine oil, and push "O" ring on nozzle end of injector until it presses against injector filter.
2. Install steel back-up washer in top counterbore of throttle body injector cavity. Lubricate large "O" ring with clean engine oil. Install "O" ring directly over back-up washer. (Scheme 8) Ensure "O" ring is seated properly in cavity and is flush with top of throttle body casting. CAUTION: Ensure back-up washer and large "O" ring is installed before injector. Improper seating of "O" ring will cause fuel leak.
3. Install "O" ring on injector. Install injector into cavity by aligning raised lug on injector base with cast-in notch of throttle body cavity. Push down on injector until fully seated. Electrical terminals of injector will be about parallel with throttle shaft. Install throttle body cover.

Relieve fuel pressure. See FUEL PRESSURE RELIEF (TBI). Remove fuel injector retainer screw and remove retainer. Using screwdriver and fulcrum on side of injector opposite connector terminals, carefully pry injector out. see scheme 21 Remove upper and lower "O" rings and discard.

1. Lubricate NEW upper and lower "O" rings with clean engine oil, and place them on injector. Ensure upper ring is in groove and lower ring is flush against filter.
2. Position injector in fuel meter assembly, with electrical connector facing cutout for wire grommet. Push injector down to seat in cavity. Install injector retainer. Coat injector retainer screw with thread locking compound and install. Tighten retainer screw to 35 INCH lbs. (4.0 N.m).

Remove air cleaner. Disconnect electrical connector. Remove retaining screws and Idle Speed Control (ISC) motor. To install, reverse removal procedure. To adjust ISC minimum and maximum authority, see ADJUSTMENTS article in this section.

Note. ISC motor is factory-calibrated and should not be disassembled. Replace motor as a complete assembly only. DO NOT soak ISC motor in carburetor cleaner.

IDLE AIR CONTROL (IAC) VALVE

On TBI models, remove air cleaner and related ducting. On all models, remove electrical connector from IAC valve. Remove IAC valve, gasket and "O" ring from throttle body assembly.

1. Inspect gasket or "O" ring for damage. Replace as necessary. Check the extended distance of IAC pintle before installing. Damage will occur if measurement is incorrect. Distance must not exceed 1 1/8" (28 mm). Measurement should be taken from valve housing flange to end of pintle cone.
2. To retract NEW IAC valve pintle, slowly exert finger pressure on valve. Install NEW "O" ring or gasket on valve. Coat "O" ring with clean engine oil. Install IAC valve. Tighten IAC valve to specification. See «TORQUE SPECIFICATIONS»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__torque-specifications) . Install electrical connector. To reset IAC valve, refer to ADJUSTMENTS article in this section.

Removal (Camaro & Firebird)

1. Relieve fuel system pressure. See «FUEL PRESSURE RELIEF (PFI)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief-pfi) . Disconnect battery negative terminal. Raise car on hoist. Drain fuel from fuel tank. Disconnect exhaust pipe at converter and rear hanger. Allow exhaust to hang over axle assembly.
2. Remove tailpipe and muffler heat shields. Remove fuel filler neck shield behind left rear tire. Remove rear suspension track bar and brace. Disconnect harness connector to fuel pump assembly.
3. Disconnect all fuel lines. Remove fuel line retaining bracket on left side and remove brake line clip from bracket.
4. Position support jack under axle assembly. Disconnect lower ends of shock absorbers. Disconnect rear stabilizer bar from frame (if equipped).
5. On models equipped with 2-piece driveshaft, remove center support bearing-to-rear axle torque arm bolts. On all models, remove rear axle torque arm-to-differential housing bolts/nuts. Wire end of rear axle torque arm aside. Remove driveshaft-to-differential yoke bolts/screws. Wire end of driveshaft aside.
6. Lower rear suspension as far as possible without damaging brake lines and cables and remove both coil springs. Remove fuel tank strap bolts. Remove fuel tank by rotating front of tank down and sliding to the right. Remove fuel pump assembly from fuel tank.

Removal (Corvette)

1. Relieve fuel system pressure. See «FUEL PRESSURE RELIEF (PFI)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief-pfi) . Remove fuse marked "Fuel Pump" from fuse block in passenger compartment. Crank engine. Engine will start and run until fuel in line is exhausted. When engine stops, engage starter again for 3 seconds to ensure engine will not start.
2. Remove battery ground cable. Remove fuel cap, fuel tank filler door. Remove filler neck housing and disconnect drain hose. Remove screws attaching fuel meter and pump assembly to tank. Disconnect fuel hoses, vapor hose and electrical connector from fuel meter and pump assembly. Pull pump up into pulsator while pulling outward away from bottom support. Remove pump.

Removal (Except Camaro, Corvette & Firebird)

1. Disconnect negative battery cable. Relieve fuel pressure. See «FUEL PRESSURE RELIEF (PFI)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief-pfi) or «FUEL PRESSURE RELIEF (TBI)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief-tbi) . Remove filler neck. Lower fuel tank. Disconnect fuel lines and electrical connection.
2. Remove fuel level sending unit and fuel pump retaining bolts or cam lock ring. Lift assembly from fuel tank and remove fuel pump from sending unit.
3. Pull fuel pump upward while pulling away from bottom support. Use care not to damage rubber insulator and strainer.

To install, reverse removal procedure using new "O" ring/gasket. Tighten fasteners to specification. See TORQUE SPECIFICATIONS .

Turn ignition switch off. Disconnect electrical connector from TPS. Remove TPS retaining screws. Remove TPS from throttle body.

1. With throttle valve in closed position, install TPS on throttle body. Ensure TPS lever engages with drive lever on throttle shaft. Install retaining screws and electrical connection.
2. The TPS on most models are self-zeroing and are not adjustable. On these models, if voltage is less than 1.25 volts, TPS does not need to be serviced. On models with adjustable TPS, adjust TPS to specification and tighten retaining screws. See ADJUSTMENTS article in this section.

OXYGEN SENSOR

Oxygen sensor is mounted in exhaust pipe, below exhaust manifold. It is equipped with a permanent pigtail which must be protected when removing sensor.

1. Ensure sensor is free of contaminants; avoid using cleaning solvents of any type. Sensor may be difficult to remove when engine temperature is less than 120°F (48°C). Excessive removal force may damage threads in exhaust manifold or pipe.
2. Disconnect negative battery cable at battery. Disconnect electrical connector from oxygen sensor. Carefully remove oxygen sensor from exhaust pipe.

1. Whenever an oxygen sensor is removed, coat threads with anti-seize compound before it is reinstalled. New oxygen sensors already have this compound applied to threads.
2. Install oxygen sensor in exhaust pipe. Tighten sensor to 30 ft. lbs. (41 N.m). Reconnect electrical connector to oxygen sensor. Reconnect negative battery cable.

SUPERCHARGER (3.8L VIN 1)

Note. Servicing of supercharger unit is limited to replacement only.

1. Relieve fuel pressure. See «FUEL PRESSURE RELIEF (PFI)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief-pfi) . Disconnect negative battery cable. Remove accessory drive belt from supercharger pulley.
2. Remove fuel injector shield. Disconnect fuel supply lines. Disconnect vacuum hoses and all electrical connectors. Remove fuel rail bolts. Remove fuel rail and injectors as an assembly. See «FUEL RAIL & INJECTORS (PFI)»(/buick/roadmaster/viii-1991-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-rail-injectors-pfi) .
3. Remove air intake duct and EGR pipe from supercharger. Disconnect throttle and cruise control cables. Remove cable bracket and tensioner bracket to supercharger mounting stud. NOTE: Tensioner bracket-to-supercharger stud must be removed or supercharger cannot be lifted high enough to clear lower intake manifold locator pins.
4. Remove supercharger-to-intake manifold bolts, supercharger gasket and coolant passage "O" rings.

Ensure locator pins are in their proper location on intake manifold. Replace gaskets and "O" rings. DO NOT use any type of sealant on gasket. To complete installation, reverse removal procedure. Tighten supercharger-to-intake manifold bolts to 19 ft. lbs. (26 N.m). Tighten fuel rail mounting bolts to 15 ft. lbs. (20 N.m).

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

See also:
• COMPUTER RELEARN PROCEDURES
• PROGRAMMABLE READ-ONLY MEMORY (PROM)
• ELECTRONIC CONTROL MODULE (ECM)
• TORQUE SPECIFICATIONS
• FUEL PRESSURE RELIEF (PFI)
• IDLE AIR CONTROL (IAC) VALVE
• FUEL PRESSURE RELIEF (TBI)
• THROTTLE BODY (TBI)
• FUEL RAIL & INJECTORS (PFI)