Engine Controls - Remove/install/overhaul Buick Century V

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.

ENGINE CONTROL MODULE (ECM)/POWERTRAIN CONTROL MODULE (PCM)

STATIC CHARGE (VOLTS)

Scheme 1

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

Note. When replacing defective ECM/PCM, remove knock sensor module or PROM from defective ECM/PCM. New ECM/PCM does not come equipped with knock sensor module or PROM (if applicable). Install knock sensor module or PROM into new ECM/PCM.

Removal

Ensure ignition switch is in OFF position. Disconnect negative battery cable. Remove electrical connectors from ECM/PCM. Remove ECM/PCM from vehicle. Remove access cover and remove knock sensor module or PROM (if applicable) from ECM/PCM.

Installation

Install knock sensor module or PROM (if applicable) in new ECM/PCM. Install access cover. Install ECM/PCM into vehicle. Connect electrical connectors to ECM/PCM. Reconnect negative battery cable to battery.

1. Disconnect negative battery cable. Remove ECM/PCM from vehicle. See «ENGINE CONTROL MODULE (ECM)/POWERTRAIN CONTROL MODULE (PCM)»(/buick/century/v-1982-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__engine-control-module-ecmpowertrain-control-module) . Position ECM/PCM so access cover faces upward. Remove access cover from ECM/PCM.
2. Using thumb and forefinger, squeeze both ends of PROM inward (outward on some models) and pull PROM up from access hole.

Note. Note reference notch locations in PROM and ECM/PCM for reassembly reference.

1. Ensure new PROM has same service number as old one. Position PROM squarely over ECM/PCM PROM access hole. Press on outer edges of PROM until PROM is firmly seated in ECM/PCM. NOTE: Ensure reference notches in both ECM/PCM 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/PCM. Install ECM/PCM in vehicle. See «ENGINE CONTROL MODULE (ECM)/POWERTRAIN CONTROL MODULE (PCM)»(/buick/century/v-1982-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__engine-control-module-ecmpowertrain-control-module) . Start engine and enter diagnostics. See appropriate G - TEST W/ CODES article in this section below. Check for trouble codes. Also refer to appropriate G - TEST W/ CODES article for code identification below. «TESTS W/CODES - 2.2L»(/buick/century/v-1982-1996/remont/testing-diagnostics/#engine-controls-tests-wcodes-22l) «TESTS W/CODES - 3.1L»(/buick/century/v-1982-1996/remont/testing-diagnostics/#engine-controls-tests-wcodes-31l)
3. If code(s) sets, PROM is either not fully seated in ECM/PCM 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.

Removal & Installation

1. Disconnect negative battery cable. Remove ECM/PCM from vehicle. See «ENGINE CONTROL MODULE (ECM)/POWERTRAIN CONTROL MODULE (PCM)»(/buick/century/v-1982-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__engine-control-module-ecmpowertrain-control-module) . Position ECM/PCM so access cover faces upward. Remove access cover from ECM/PCM.
2. Using thumb and forefinger, squeeze both ends of knock sensor module inward and pull module up from access hole. To install, reverse removal procedure. Ensure module latches into holder in ECM/PCM.

1. Disconnect negative battery cable. Disconnect connectors at ignition module. (Scheme 2) Disconnect spark plug wires from coil pack. Remove coil pack/ignition module assembly. For ignition module location, see COMPONENT LOCATIONS in «SYSTEM/COMPONENT TESTS - 3.1L»(/buick/century/v-1982-1996/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-31l) and «SYSTEM/COMPONENT TESTS - 2.2L»(/buick/century/v-1982-1996/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-22l) articles 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. Tighten mounting bolts/nuts to specification. See appropriate «TORQUE SPECIFICATIONS»(/buick/century/v-1982-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul).

Scheme 2

Scheme 3

Removal & Installation (3.1L)

Disconnect negative battery cable. On 3.1L, remove serpentine belt. Remove power steering pump assembly. Disconnect sensor harness connector. Remove camshaft position sensor bolt and remove sensor. To install, reverse removal procedure.

Disconnect negative battery cable. 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.

1. Disconnect negative battery cable. On 3.1L, turn steering wheel to left, and raise and support vehicle. Remove intermediate exhaust pipe, and rack and pinion heat shield. Remove generator cooling duct sensor.
2. Disconnect sensor harness connector. 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. Tighten sensor bolt to specification. See appropriate «TORQUE SPECIFICATIONS»(/buick/century/v-1982-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul) .

1. Disconnect negative battery cable. Remove serpentine belt from crankshaft pulley. Raise and support vehicle.
2. Remove crankshaft harmonic balancer bolt. Using Balancer Remover (J-38197), remove harmonic balancer. Disconnect sensor harness connector. Remove sensor bolts. Remove sensor.
3. To install, reverse removal procedure. Tighten sensor and harmonic balancer bolts to specification. See «TORQUE SPECIFICATIONS»(/buick/century/v-1982-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul) .

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.

FUEL PRESSURE RELIEF

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 (SA9127E for Saturn or J-34730-1 for all other models) 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.

THROTTLE BODY (MFI)

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

1. Relieve fuel pressure. See «FUEL PRESSURE RELIEF»(/buick/century/v-1982-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief) . Disconnect negative battery cable. Remove air intake 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/century/v-1982-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul) . Refill cooling system (if drained).
2. If installing new Idle Air Control (IAC) valve, ensure IAC pintle length setting is adjusted before installation. See IDLE AIR CONTROL (IAC) VALVE. Adjust idle speed and TP sensor (if removed, and if adjustable). See «ADJUSTMENTS»(/buick/century/v-1982-1996/remont/adjustments/#engine-controls-adjustments) article in this section.

Removal (2.2L)

1. Relieve fuel pressure. See «FUEL PRESSURE RELIEF»(/buick/century/v-1982-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief) . Disconnect negative battery cable. Remove air intake duct (if necessary). Disconnect pressure regulator vacuum hose. Remove fuel return line and "O" ring from pressure regulator.
2. Remove pressure regulator screws. Remove pressure regulator from fuel rail. Remove pressure regulator retainer and spacer assembly from fuel rail (if equipped). Remove fuel inlet "O" ring from pressure regulator. Remove and discard filter screen if dirty.

To install, reverse removal procedure. DO NOT reuse "O" rings. Lubricate fuel inlet "O" ring with oil and install in regulator. Replace filter screen as necessary. Tighten screws to specification. See appropriate TORQUE SPECIFICATIONS .

Removal (3.1L)

1. Relieve fuel pressure. See «FUEL PRESSURE RELIEF»(/buick/century/v-1982-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief) . Disconnect negative battery cable. Remove intake manifold plenum and gaskets. Disconnect pressure regulator vacuum hose. Remove fuel return line and "O" ring from pressure regulator.
2. Remove pressure regulator screws. Remove pressure regulator from fuel rail. Remove pressure regulator retainer and spacer assembly from fuel rail (if equipped). On 3.1L, remove fuel inlet "O" ring from pressure regulator. Remove and discard filter screen if dirty.

To install, reverse removal procedure. DO NOT reuse "O" rings. Lubricate fuel inlet "O" ring with oil and install in regulator. Replace filter screen as necessary. Tighten screws to specification. See appropriate TORQUE SPECIFICATIONS .

FUEL RAIL & INJECTORS (MFI)

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

1. Relieve fuel pressure. See «FUEL PRESSURE RELIEF»(/buick/century/v-1982-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief). Disconnect negative battery cable. Remove air intake duct (if necessary). On 3.1L, remove intake manifold plenum and gaskets.
2. Disconnect vacuum hose at fuel pressure regulator. Disconnect and plug fuel return line at pressure regulator. Disconnect and plug fuel inlet line at fuel rail. Disconnect electrical connectors from injectors.
3. Remove fuel rail retaining bolts. Remove fuel rail from intake manifold using equal force on both sides of the fuel rail. (Scheme 4) Remove injector-to-fuel rail retaining clip (if equipped). Remove injectors from fuel rail. Remove injector "O" rings and discard.

To install, reverse removal procedure. Coat NEW injector "O" rings with clean engine oil. Install injector-to-fuel rail retaining clip with open end facing injector electrical connection. Position fuel rail on intake manifold. Push down on rail to seat injectors in manifold. Tighten fuel rail retaining bolts. See the appropriate TORQUE SPECIFICATIONS . To complete installation, reverse removal procedure.

1. Relieve fuel pressure. See «FUEL PRESSURE RELIEF»(/buick/century/v-1982-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief) . Disconnect negative battery cable. Remove upper manifold. Remove fuel return line retaining bracket nut and bracket. Disconnect and plug fuel return line at pressure regulator.
2. Disconnect vacuum hose at fuel pressure regulator. Remove fuel pressure regulator. Disconnect and plug fuel inlet line at injector retainer. Remove injector retainer retaining screws. Carefully slide injector retainer from injector slots and remove from intake manifold.
3. Disconnect electrical connectors from injectors. Remove injectors from intake manifold. Remove injector "O" rings and discard.

To install, reverse removal procedure. Coat NEW injector "O" rings with clean engine oil. Position injectors into intake manifold and injector retainer over injectors. Tighten injector retainer screws. See appropriate TORQUE SPECIFICATIONS . To complete installation, reverse removal procedure.

Scheme 4

1. Disconnect negative battery cable. Relieve fuel pressure. See «FUEL PRESSURE RELIEF»(/buick/century/v-1982-1996/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief) . 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 and gasket.

Turn ignition switch to OFF position. Disconnect electrical connector from TP sensor. Remove TP sensor retaining screws. Remove TP sensor from throttle body.

1. With throttle valve in closed position, install TP sensor on throttle body. Ensure TP sensor lever engages with drive lever on throttle shaft. Install retaining screws and electrical connection.
2. TP sensor is self-zeroing and is not adjustable.

OXYGEN SENSOR

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

1. Ensure sensor is free of contaminants. DO NOT use 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. 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.

TORQUE SPECIFICATIONS (2.2L)

TORQUE SPECIFICATIONS (2.2L)

TORQUE SPECIFICATIONS (3.1L)

TORQUE SPECIFICATIONS (3.1L)

See also:
• COMPUTER RELEARN PROCEDURES
• TESTS W/CODES - 2.2L
• TESTS W/CODES - 3.1L
• SYSTEM/COMPONENT TESTS - 3.1L
• SYSTEM/COMPONENT TESTS - 2.2L
• ADJUSTMENTS
• ENGINE CONTROL MODULE (ECM)/POWERTRAIN CONTROL MODULE (PCM)
• TORQUE SPECIFICATIONS
• FUEL PRESSURE RELIEF