Fuel Injection System - 2.3l Mpfi Ford Mustang III рестайлинг

APPLICATION

FUEL INJECTION SYSTEM APPLICATIONS

DESCRIPTION

The electronic fuel injection system is a pulse time, Multi-Point Fuel Injection (MPFI) system. On-board Electronic Engine Control (EEC-IV) system has Electronic Control Assembly (ECA) which receives inputs from engine and vehicle sensors to compute required fuel flow rate necessary to maintain prescribed air/fuel ratio throughout entire engine operational range.

The ECA controls fuel injectors to meter fuel quantity into intake ports. Injector "on" time is the only controlled variable in fuel delivery system.

FUEL SUPPLY

Fuel is supplied by chassis mounted or in-tank electric fuel pump. Some models use both in-tank low pressure pump and externally mounted high pressure pump. Pump delivers fuel from fuel tank through 20-micron fuel filter to fuel charging manifold assembly.

Fuel charging manifold assembly incorporates electrically actuated fuel injectors directly above each intake port. Injectors spray metered quantity of fuel into intake air. Constant fuel pressure is maintained to injector nozzles by pressure regulator.

Fuel pressure regulator is connected in series with fuel injectors and is positioned downstream from them. Excess fuel supplied by pump, but not consumed by engine, passes through regulator and returns to fuel tank through fuel return line.

On 2.3L engines, all injectors are energized simultaneously once every crankshaft revolution.

ECA determines required fuel flow rate necessary to maintain prescribed air/fuel ratio for given engine operation by measuring quantity of air entering engine. Computer determines needed injector pulse width (period of time that injectors are energized) and energizes injector to meter quantity of fuel.

VAF system measures intake air quantity with vane airflow meter and integral air charge temperature sensor. Speed/density control system uses Throttle Position Sensor (TPS), Manifold Absolute Pressure (MAP) sensor and Air Charge Temperature (ACT) sensor to determine intake air quantity.

FUEL INJECTORS

Fuel injector nozzles are solenoid operated valves which meter and atomize fuel delivered to engine. Injectors are mounted in lower intake manifold with their nozzles injecting fuel just upstream of engine intake valves.

Injector bodies consist of solenoid actuated pintle and needle valve assembly. Electrical control signal from ECA unit activates injector solenoid, causing pintle to move inward off its seat, allowing fuel to flow.

Since injector flow orifice is fixed and fuel pressure at injector tip is constant, fuel flow to engine is regulated by how long solenoid is energized. This length of time is known as "pulse width". Atomization spray is obtained by shape of pintle.

Scheme 11

FUEL PRESSURE REGULATOR

Fuel pressure regulator is attached to fuel supply manifold assembly downstream of fuel injectors. It regulates fuel pressure supplied to injectors. Regulator is diaphragm operated relief valve in which one side of diaphragm senses fuel pressure and other side is subjected to intake manifold pressure.

Fuel pressure is controlled by spring preload applied to diaphragm. Balancing one side of diaphragm with manifold pressure maintains constant fuel pressure at injectors. Excess fuel is by-passed through regulator and returned to fuel tank.

Scheme 12

MAP & ACT SENSORS

Manifold Absolute Pressure (MAP) sensor compares manifold vacuum and manifold pressures to obtain manifold absolute pressures. Resulting input signal from sensor provides ECA with engine load and air density information. This sensor is located on firewall in engine compartment or on air cleaner.

Air Charge Temperature (ACT) sensor measures air/fuel mixture temperature. Resulting input signal from sensor provides ECA with density correction factor, which is used to calculate airflow and to proportion cold enrichment fuel flow. This sensor is located in intake manifold runner or side of throttle body.

FUEL SUPPLY MANIFOLD ASSEMBLY

Fuel supply manifold assembly (fuel rail) delivers high pressure fuel from fuel pump supply line to fuel injectors. Fuel rail consists of tubular rail or stamping with injector connectors. Fuel pressure regulator is mounted on flange attached to rail. Rail also has mounting attachments which locate and secure fuel injectors in intake manifold.

THROTTLE BODY ASSEMBLY

Throttle body assembly controls airflow to engine through a butterfly valve. Throttle position is controlled by either linkage or cable/cam mechanism. Body is one-piece aluminum casting with single bore and air by-pass channel.

Air by-pass channel carries idle airflow which is regulated by air by-pass valve. Air by-pass valve is controlled by ECA to adjust both cold and warm idle speeds. Air by-pass valve uses solenoid valve to vary volume of idle airflow allowed to enter by-pass channel.

AIR INTAKE SYSTEM

Runner lengths are tuned for optimum engine torque output. Manifold provides mounting flanges for throttle body assembly, fuel supply manifold, accelerator controls, EGR valve and supply tube.

Vacuum ports are provided to support various engine accessories. Mounting sockets for fuel injectors are machined to prevent both air and fuel leakage. Pockets in which injectors are mounted are placed so injectors spray fuel directly in front of each intake valve.

FUEL PUMP CONTROL

When ignition switch is turned to "ON" position, EEC power relay is energized (contacts closed). Power is provided to fuel pump relay and to timer in ECA. Fuel pump receives power through fuel pump relay contacts. If ignition switch is not turned to "START" position, timer in ECA will open ground circuit after approximately one second. ECC senses engine speed and shuts off fuel pump by opening ground circuit to fuel pump relay when engine stops, or when engine speed drops to less than 120 RPM.

Opening ground circuit de-energizes fuel pump relay (contacts opened) and de-energizes fuel pump. This function allows pressurization of fuel system. When ignition switch is turned to "START" position, ECA operates fuel pump relay to provide fuel for starting engine while cranking.

INERTIA SWITCH

In event of collision, electrical contacts in inertia switch will open. This will automatically shut off fuel pump. Fuel pump will shut off even if engine does not stop running. Engine will top shortly due to lack of fuel. It will not be possible to restart engine until inertia switch is manually reset. To reset inertia switch, depress button on top of switch.

On RWD vehicles, inertia switch is located in trunk, on left hinge support or behind trim panel.

On 3-door Mustang, it is located near left taillight.

On FWD, switch is located behind trim panel in left side of trunk.

PRELIMINARY CHECKS

Following systems and components must be in good condition and operating properly before beginning diagnosis of fuel injection system

1. Battery condition
2. State of tune
3. Fuel delivery system
4. All wiring and vacuum connections
5. Air cleaner and ducting
6. Cooling system NOTE: Some vehicles may not include all components listed in this section.

Engine Does Not Crank

Check starting and charging systems. Repair any problems with these systems before attempting to repair fuel injection system.

Engine Cranks But Does Not Start

1. Ensure fuel tank contains adequate amount of fuel. Do not assume that fuel gauge is correct. Check fuel for dirt, water or other contamination.
2. Check ignition system for strong secondary current at spark plugs. If no spark exists or if spark is weak, repair ignition system before continuing with fuel injection diagnosis.
3. Check fuel lines and fittings for leaks. If no leaks are found, check fuel delivery system for proper operation, pressure and volume.
4. Check if inertia switch is tripped and reset if necessary. Check for defective injector, sticking Throttle Position Sensor (TPS), or defective Coolant Temperature Switch (CTS). NOTE: For problems requiring EEC-IV diagnosis, see FORD MOTOR CO. EEC-IV article in COMPUTERIZED ENGINE CONTROLS section.

Hard to Start (Cold)

Inoperative ISC motor, EEC-IV diagnosis required. TPS stuck at Wide Open Throttle (WOT), or inoperative injector. Crank engine with TPS disconnected. Check for injector discharge at injector.

Rough Idle (Cold)

Injector leaking or inoperative. Check operation of injector. Injector "O" ring seal leaking. Perform injector/regulator leakage test. Check for possible vacuum leak.

Stall, Stumble, Hesitation (Hot or Cold)

TPS failure. EEC-IV diagnosis required.

Hard Start (Hot)

1. Inoperative ISC motor. EEC-IV diagnosis required. TPS stuck at WOT. EEC-IV diagnosis required. Injector leaking or inoperative. Check for fuel discharge while cranking engine.
2. Excessive fuel pressure. Service pressure regulator and fuel return line. Contaminated fuel pressure regulator valve and seat. Service pressure regulator or check fuel pressure bleed down after engine has been turned off. Injector "O" ring seal leaking. Perform injector leakage test.

Rough Idle (Hot)

Injector leaking or inoperative. Check operation of injector. Injector "O" ring leaking. Perform injector leakage test.

Stalls On Deceleration/Quick Stop

ISC inoperative. EEC-IV diagnosis required.

Lack Of Power

Fuel filter may be clogged. Check fuel delivery and repair as needed.

Reduced Top Speed/Power

Plugged injectors. Check injector discharge at injector. Damaged fuel pressure regulator. Service or replace as necessary.

Surges At Cruise

Plugged or leaking injectors. Check injector operation. Check also for restricted fuel filter.

FUEL PUMP

The fuel pump may be activated by grounding the fuel pump lead at the SELF-TEST connector. Use a jumper lead, and ground the "FP" terminal with the ignition on. This activates the fuel pump. (Scheme 13) For additional circuit test information, see CIRCUIT TEST C2, in EEC-IV article in COMPUTER CONTROLS section.

Scheme 13

FUEL PRESSURE SPECIFICATIONS - psi (kg/cm 2 )

INJECTORS

1. Connect tachometer to engine. Run engine at idle. Disconnect and reconnect injectors individually. If each injector causes a momentary drop in engine speed of at least 100 RPM, injectors are giving proper fuel delivery. RPM drop should only be momentary as ISC will attempt to re-establish correct idle RPM.
2. Replace any injectors that do not cause sufficient drop in engine speed. When test is complete and all injectors cause equal drop in speed, shut off engine. In order to check curb idle, refer to emission control specifications on decal in engine compartment.

INJECTOR CIRCUIT

Disconnect all injector harness connectors. Using digital ohmmeter, check resistance across terminals of each injector. See INDIVIDUAL INJECTOR RESISTANCE . Disconnect injector bank harness connector, check resistance of injector bank. See INJECTOR BANK RESISTANCE . Repair wiring or replace any injector circuit not within specification.

INDIVIDUAL INJECTOR RESISTANCE

INJECTOR BANK RESISTANCE

Note. For further component testing and information, see EEC-IV article in COMPUTER CONTROLS sections.

PREPARATION

Before removing fuel charging assembly or servicing components installed on engine, following steps MUST be performed

1. Turn ignition off.
2. Disconnect negative battery lead.
3. Remove fuel cap to relieve tank pressure.
4. Release system pressure. See «FUEL SYSTEM PRESSURE RELEASE»(/ford/mustang/iii-1986-1993/remont/testing-diagnostics/#fuel-injection-system-23l-mpfi__fuel-system-pressure-release) .
5. Disconnect fuel supply and return lines.

FUEL SYSTEM PRESSURE RELEASE

Remove fuel tank cap. Using Fuel Pressure Gauge (T80L-9974-B), release pressure from system at pressure relief valve (schrader valve) on fuel injection manifold rail.

Removal (Spring Lock Coupling)

1. Using Spring Lock Coupling Remover (D87L-9280-A for 3/8" or D87L-9280-B for 1/2"), remove clip from coupling. Place remover over coupling so intrusion is positioned on cage opening side of coupling. (Scheme 14)
2. Close remover over coupling. Push remover into cage opening to release female fitting from garter spring. Pull male and female halves of coupling apart. Remove tool from disconnected spring lock coupling.

Scheme 14

Scheme 15

1. Ensure garter spring in cage of male fitting is not damaged, replace if necessary. Clean all dirt from both pieces of coupling. Check "O" rings for damage and replace if necessary using proper fuel resistant "O" rings.
2. Lubricate "O" rings and inside of female fitting with clean engine oil. Snap fitting together. Install retaining clip onto coupling. Ensure horseshoe portion of clip is over the coupling. (Scheme 15) Do not install retaining clip over rubber fuel line.

Removal (Hairpin Clip Coupling)

Remove hairpin clip from fitting. Spread each clip leg about 1/8" to disengage body. Push legs into fitting. While pulling lightly on triangular end of clip. Work it clear of tube and fitting. Pull fitting and steel line in axial direction. Use twisting motion while pulling fitting loose.

Installation (Hairpin Clip Coupling)

Insert clip into any 2 adjacent openings with triangular portion pointing away from fitting opening. Install clip to fully engage the body. Clean end of fitting. Align fitting and tube axially and push fitting onto tube end. When fitting is engaged, a definite click will be heard.

Removal (2.3L Tempo & Topaz)

1. Remove air cleaner outlet tube between vane air meter and air throttle body by loosening 2 clamps. Disconnect and remove accelerator and speed control cables from accelerator mounting bracket and throttle lever.
2. Disconnect top manifold vacuum fitting connections by disconnecting both rear vacuum line for dash panel vacuum tree and vacuum line at intake tee. Disconnect hoses from PCV valve at intake manifold.
3. Disconnect vacuum line at EGR valve, fuel pressure regulator and MAP sensor (if equipped). Disconnect EGR tube from upper intake manifold by loosening compression nut while supporting connector. Remove only upper bolt to disconnect upper manifold support bracket.
4. Disconnect wiring at main engine harness and ECT sensor (if equipped). Disconnect fuel lines. Remove manifold mounting nuts. Disconnect lower manifold support bracket by removing top bolt. Remove manifold with wiring harness and gasket.

Installation (2.3L Tempo & Topaz)

1. Clean and inspect mounting faces of fuel charging manifold assembly and cylinder head. Surface must be clean and flat. Clean and lubricate manifold stud threads. Install new gasket. Install manifold assembly to head and tighten top middle nut finger tight.
2. Install fuel return line in fuel supply manifold. Install 2 manifold mounting nuts finger tight. Install remaining 3 manifold mounting nuts and tighten all nuts. Connect upper and lower manifold support brackets and tighten bolts. Install EGR tube with oil coated compression nut.
3. Connect vacuum lines to throttle body port. Connect large PCV vacuum line to upper manifold. Reconnect all manifold vacuum lines. Connect accelerator and speed control cables. Install air supply tube and tighten clamps.
4. Reconnect wiring harness at ECT sensor and EEC harness. Connect fuel supply hose from fuel filter to fuel rail. Connect fuel return line. Connect battery ground and refill cooling system.

Removal (2.3L Mustang)

1. Label and disconnect all wiring and vacuum lines interfering with removal and position out of work area. Disconnect all linkage interfering with removal and position out of work area.
2. Disconnect air intake hose. Disconnect PCV system by disconnecting hose from fitting on underside of upper intake manifold. Loosen hose clamp on water by-pass line at lower intake manifold, and disconnect hose. Disconnect EGR tube from EGR valve by removing flange nut.
3. Remove engine oil dipstick bracket retaining screw. Remove 4 upper intake manifold retaining nuts. Remove upper intake manifold and air throttle body assembly.
4. Disconnect fuel inlet and return lines. See «FUEL LINE CONNECTOR»(/ford/mustang/iii-1986-1993/remont/testing-diagnostics/#fuel-injection-system-23l-mpfi) under REMOVAL & INSTALLATION. Remove 2 fuel supply manifold retaining bolts. Remove 4 upper retaining bolts from lower manifold. Remove lower manifold.

Installation (2.3L Mustang)

Clean all gasket mounting surfaces. Install lower intake manifold and tighten in proper sequence. (Scheme 17) To complete installation, reverse removal procedure. Tighten upper-to-lower intake manifold bolts in sequence. (Scheme 17)

Scheme 16

Scheme 17

AIR INTAKE THROTTLE BODY

Note. DO NOT remove thin protective coating from throttle plates or bores.

Removal

Remove nuts and bolts from throttle body. Label and disconnect electrical connectors interfering with throttle body removal. Disconnect air cleaner outlet tube. Label and disconnect vacuum hoses. Disconnect throttle and speed control cables. Remove throttle bracket. Carefully separate throttle body from upper intake manifold. Remove and discard gasket.

Installation

Ensure that gasket surfaces are clean. Install throttle body gasket on studs. To complete installation, reverse removal procedure.

Disconnect TPS from wiring harness. Scribe marks on throttle body and TPS for reassembly reference. Remove mounting screws and TPS.

Slide rotary tangs of TPS into position over throttle shaft blade with wires pointing down. On 3.0L engines, Red seal must be inside connector housing. On all models, rotate TPS clockwise to installed position. Align scribe marks on throttle body and TPS. Secure sensor to throttle body assembly with retaining bolts. Connect wiring.

1. Remove fuel tank cap. Using a pressure gauge, release pressure from system by opening pressure relief valve on fuel injector manifold. Disconnect fuel supply and return lines.
2. Disconnect wiring harness from injectors. Disconnect vacuum line from fuel pressure regulator valve. Remove fuel injector manifold retaining bolts. Disengage manifold from fuel injectors and remove manifold. Grasp injector body and pull up while gently rocking injector.

1. Inspect "O" rings, "plastic hat" and washer over injector pintle. Make sure injector caps are clean. Use light twisting motion to install injectors in manifold assembly. Make sure injectors are well seated in fuel manifold assembly.
2. Assemble manifold to charging assembly with retaining bolts. Connect fuel supply and return lines. Connect fuel injector wiring harness. Connect vacuum line to fuel pressure regulator.

Remove vacuum line at pressure regulator. Remove 3 Allen retaining screws from regulator housing. Remove pressure regulator assembly with gasket and "O" ring. Discard gasket and inspect "O" ring for cracks or deterioration.

Lubricate "O" ring with light oil. Make sure gasket surfaces are clean. Install "O" ring and new gasket on regulator. Install fuel pressure regulator on injector manifold and tighten 3 screws.

Relieve fuel system pressure. Drain fuel tank. Lower fuel tank enough to disconnect fuel tank hoses and electrical connectors. Disconnect fuel tank hoses and electrical connectors. Remove fuel tank. Using Fuel Tank Sender Wrench (D84P-9275-A), remove fuel pump lock ring. Remove fuel pump.

1. Clean fuel pump mounting flange, fuel tank mounting surface and seal ring groove. To hold new seal ring in place during installation, apply a light coating of Long Life Lubricant (C1AZ-19590-BA).
2. Install seal ring in fuel ring groove. Carefully install fuel pump and bracket assembly. Ensure locating keys are in keyway and seal ring remains in groove. Hold pump assembly in place and install locking ring finger tight. Ensure that all locking tabs are under lock ring tabs. Tighten retainer.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

WIRING DIAGRAMS

See appropriate article in COMPUTERIZED ENGINE CONTROLS section.

See also:
• INDIVIDUAL INJECTOR RESISTANCE
• FUEL SYSTEM PRESSURE RELEASE