Engine Controls - Remove/install/overhaul Buick LeSabre VII

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.

POWERTRAIN CONTROL MODULE (PCM)

STATIC CHARGE (VOLTS)

Scheme 1

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

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

Removal

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

Installation

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

Disconnect negative battery cable. Remove PCM from vehicle. See POWERTRAIN CONTROL MODULE (PCM) . Position PCM so access cover faces upward. Remove access cover from PCM. 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 PCM for reassembly reference.

1. Ensure new PROM has same service number as old one. Position PROM squarely over PCM PROM access hole. Press on outer edges of PROM until PROM is firmly seated in PCM. NOTE: Ensure reference notches in both PCM and PROM are properly aligned. If PROM is installed backward, PROM will be destroyed when ignition is turned on.
2. Install PROM access cover on PCM. Install PCM in vehicle. See «POWERTRAIN CONTROL MODULE (PCM)»(/buick/lesabre/vii-1992-1999/remont/removal-installation/#engine-controls-removeinstalloverhaul__powertrain-control-module-pcm) . Start engine and enter diagnostics. See «TESTS W/CODES»(/buick/lesabre/vii-1992-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes) article in this section. Check for diagnostic trouble codes. See «TESTS W/CODES»(/buick/lesabre/vii-1992-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes) article in this section for code identification.
3. If code(s) sets, PROM is either not fully seated in PCM or installed backward, has bent pins or is defective. If bent pins crack when trying to straighten, replace PROM. If PROM is installed backward or is defective, replace PROM.

Removal & Installation

1. Disconnect negative battery cable. Remove PCM from vehicle. See «POWERTRAIN CONTROL MODULE (PCM)»(/buick/lesabre/vii-1992-1999/remont/removal-installation/#engine-controls-removeinstalloverhaul__powertrain-control-module-pcm) . Position PCM so access cover faces upward. Remove access cover from 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 PCM.

1. Disconnect negative battery cable. Disconnect 14-way connector at ignition control module. Disconnect spark plug wires from coil pack. Remove 6 screws retaining coils to ignition control module. Tilt coil assembly back, and disconnect connectors between ignition coil and module. Remove coil pack.
2. Remove nuts and washers securing ignition control module to bracket. Remove ignition control module. To install, reverse removal procedure. Tighten retaining screws and nuts to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/vii-1992-1999/remont/removal-installation/#engine-controls-removeinstalloverhaul) .

Disconnect negative battery cable. Disconnect sensor harness connector. Remove camshaft position sensor bolt and remove sensor. To install, reverse removal procedure. Tighten sensor bolt to specification. See TORQUE SPECIFICATIONS .

1. Disconnect negative battery cable. 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. Using Balancer Remover (J-38197), remove harmonic balancer. Remove crankshaft position sensor shield ( DO NOT use pry bar). (Scheme 2) Disconnect crankshaft position sensor harness connector. Remove crankshaft position sensor from engine block.
3. To install, reverse removal procedure. Apply Thread Sealer (GM 1052080) to threads of harmonic balancer bolt. Tighten sensor and harmonic balancer bolts to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/vii-1992-1999/remont/removal-installation/#engine-controls-removeinstalloverhaul).

Scheme 2

Disconnect negative battery cable. Disconnect spark plug wires from coil pack. Remove 6 screws retaining coils to ignition control module. Tilt coil assembly back, and disconnect connectors between ignition coil and module. Remove coil pack. To install, reverse removal procedure. Tighten retaining screws to specification. See TORQUE SPECIFICATIONS .

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 (J-34730-1) 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

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

1. Relieve fuel pressure. See «FUEL PRESSURE RELIEF»(/buick/lesabre/vii-1992-1999/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/lesabre/vii-1992-1999/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»(/buick/lesabre/vii-1992-1999/remont/removal-installation/#engine-controls-removeinstalloverhaul__idle-air-control-iac-valve) . Adjust idle speed and TP sensor (if removed, and if adjustable). See «ADJUSTMENTS»(/buick/lesabre/vii-1992-1999/remont/adjustments/#engine-controls-adjustments) article in this section.

1. Relieve fuel pressure. See «FUEL PRESSURE RELIEF»(/buick/lesabre/vii-1992-1999/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 TORQUE SPECIFICATIONS .

FUEL RAIL & INJECTORS

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/lesabre/vii-1992-1999/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief). Disconnect negative battery cable. Remove air intake duct (if necessary).
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 fuel rail. (Scheme 3) 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 TORQUE SPECIFICATIONS . To complete installation, reverse removal procedure.

Locating Fuel Rail Assembly Components (Typical). Scheme 3

IDLE AIR CONTROL (IAC) VALVE

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/lesabre/vii-1992-1999/remont/removal-installation/#engine-controls-removeinstalloverhaul) . Install electrical connector. To reset IAC valve, refer to «ADJUSTMENTS»(/buick/lesabre/vii-1992-1999/remont/adjustments/#engine-controls-adjustments) article in this section.

FUEL FILTER

Before replacing a fuel filter it is necessary to relieve fuel system pressure. Refer to FUEL PRESSURE RELIEF .

The fuel filter is located under the front of the vehicle alongside the right body rail.

1. Hoist vehicle. CAUTION: To help avoid personal injury when a vehicle is on a hoist, provide additional support for the vehicle at the opposite end from which components are being removed. This will reduce the possibility of the vehicle falling off of the hoist.
2. Detach fuel pipe inlet connector.
3. Loosen filter from bracket.
4. Disconnect outlet connector by using same procedure as that for inlet connector, and remove filter from vehicle.

1. Place filter loosely in position.
2. Install outlet connector onto filter male tube ends pressing firmly together.
3. Check that connector is locked on by trying to pull the connector away from the male tube end of filter.
4. Install inlet connector using same procedure as that for front connector. Check that connector is locked on.
5. Secure filter to vehicle.
6. Lower vehicle.
7. Start engine and inspect for leaks.

1. Disconnect negative battery cable. Relieve fuel pressure. See «FUEL PRESSURE RELIEF»(/buick/lesabre/vii-1992-1999/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. On 4.9L with adjustable TP sensor, adjust TP sensor to specification and tighten retaining screws. See «ADJUSTMENTS»(/buick/lesabre/vii-1992-1999/remont/adjustments/#engine-controls-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 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.

SUPERCHARGER

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

Removal (3.8L VIN 1)

1. Relieve fuel pressure. See «FUEL PRESSURE RELIEF»(/buick/lesabre/vii-1992-1999/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-pressure-relief) . Disconnect negative battery cable. Remove accessory drive belt from supercharger pulley.
2. Remove fuel injector sight shield. Disconnect fuel lines from fuel rail. Disconnect vacuum hoses. Disconnect injector electrical connectors. Disconnect electrical from front of supercharger. Remove fuel rail bolts. Remove fuel rail and injectors as an assembly. See «FUEL RAIL & INJECTORS»(/buick/lesabre/vii-1992-1999/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-rail-injectors) .
3. Disconnect electrical connectors from IAC valve, TP sensor, MAP sensor, MAF sensor, EGR valve, boost control solenoid, and engine coolant temperature sensor. Remove air intake duct from throttle body. Remove EGR pipe from supercharger. Disconnect throttle and cruise control cables. Remove boost pressure manifold and vacuum block. 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 throttle body from supercharger. 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 retaining bolts to 97 INCH lbs. (11 N.m).

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

See also:
• COMPUTER RELEARN PROCEDURES
• TESTS W/CODES
• ADJUSTMENTS
• POWERTRAIN CONTROL MODULE (PCM)
• TORQUE SPECIFICATIONS
• FUEL PRESSURE RELIEF
• IDLE AIR CONTROL (IAC) VALVE
• FUEL RAIL & INJECTORS