REMOVAL & INSTALLATION
See Figures 1 and 2
- Disconnect the negative battery cable. Remove the air cleaner.
- Release the pressure from the fuel system.
- Disconnect the throttle cable and transmission throttle valve lever.
- Unfasten and label the fuel, vacuum and electrical connections. Use care to prevent combustion of spilled fuel.
- Remove the fuel charging assembly retaining nuts then remove the fuel charging assembly.
- Remove the mounting gasket from the intake manifold.
- Installation is the reverse of removal. Tighten the fuel charging assembly nuts evenly to 120 inch lbs. (13 Nm).
DISASSEMBLY & ASSEMBLY
See Figure 3
- Remove the air cleaner mounting stud in order to separate the upper body from the throttle body.
- Turn the fuel charging assembly (throttle body) over and remove the four screws from the bottom of the throttle body.
- Separate the throttle body (lower half) from the main body (upper half).
- Remove the gasket. If it is stuck and scraping is necessary, use only a plastic or wood scraper. Take care not to damage the gasket surfaces.
- Remove the three pressure regulator mounting screws. Remove the pressure regulator.
- Unfasten the electrical connectors at each injector by pulling outward on the connector and not on the wire. Loosen but do not remove the wiring harness retaining screw. Push in on the harness tabs to remove it from the upper body.
- Remove the fuel injector retaining screw. Remove the injection retainer.
- Pull the injectors, one at a time, from the upper body. Mark the injectors for identification, they must be reinstalled in the same position (choke or throttle side). Each injector is equipped with a small O-ring. If the O-ring does not come out with the injector, carefully pick it out of the body.
- Remove the Schrader valve assembly.
- Remove the thermostat cover by drilling the retaining rivets. A 1 / 8 in. or No. 30 drill is required. A mounting kit for installation is available from Ford.
- Remove the thermostat cap retaining ring, choke cap and gasket. Remove the thermostat lever screw and lever. Remove the fast idle cam assembly and control rod positioner.
- Hold the control diaphragm cover in position and remove the two mounting screws. Carefully remove the cover, spring and pulldown diaphragm.
- Remove the fast idle retaining nut, fast idle cam adjuster lever, fast idle lever and E-clip.
- Remove the position sensor connector bracket retaining screw. Mark the throttle body and throttle position sensor for correct installation position. Remove the throttle sensor retaining screws and slide the sensor off of the throttle shaft. Remove the throttle positioner retaining screw and remove the throttle positioner.
- Perform any necessary cleaning or repair.
- Assemble the upper body by first installing the Schrader valve assembly.
- Lubricate the new injector O-rings with a clean engine oil. Install the O-rings on each injector. Install the injectors in their appropriate position. Use a light, twisting, pushing motion to install the injectors.
- Install the injector retainer and tighten the retaining screw to 30-60 inch lbs. (3-7 Nm).
- Install the injector wiring harness and snap into position. Tighten the harness retaining screw to 8-10 inch lbs. (0.9-1.1 Nm).
- Snap the electrical connectors into position on the injectors. Lubricate the fuel pressure regulator O-ring with oil. Install the O-ring and new gasket on the regulator. Install the regulator and tighten the retaining screws to 27-40 inch lbs. (3-4 Nm).
- Install the throttle positioner onto the throttle body. Tighten the retaining screw to 32-44 inch lbs. (3-5 Nm).
- Hold the throttle position sensor with the identification mark in the 12 o'clock position. The two rotary tangs should be at 3 o'clock and 9 o'clock positions.
- Slide the sensor onto the throttle shaft with the identification mark still in the 12 o'clock position. Hold the sensor firmly against the throttle body.
- Rotate the sensor until the identification marks on the sensor and body are aligned. Install the retaining screws and tighten to 13-18 inch lbs. (1-2 Nm).
- Install the sensor wiring harness bracket retaining screw, tighten to 18-22 inch lbs. (2-2.5 Nm). Install the E-clip, fast idle lever, fast idle adjustment lever and fast idle retaining nut. Tighten the retaining nut to 16-20 inch lbs. (2-2.5 Nm).
- Install the pulldown diaphragm, spring and cover. Hold the cover in position and tighten the retaining screws to 13-19 inch lbs. (1-2 Nm).
- Install the fast idle control rod positioner, fast idle cam and the thermostat lever. Tighten the retaining screw to 13-19 inch lbs. (1-2 Nm).
- Install the thermostat gasket, bi-metal spring, cap and retaining ring. Install new rivets and snug them with the rivet gun. Do not break the rivets yet, loosely install so the thermostat cover can rotate. Index the thermostat and break rivets to tighten.
- Install the gasket between the main body and the throttle body. Place the throttle body in position. Install the four retaining screws loosely. Install the air cleaner stud and tighten to 70-95 inch lbs. (8-11 Nm). Tighten the four retaining screws.
- The rest of the assembly is in the reverse order of disassembly.
Butterfly Valves (Air Flow Control)
See Figure 4
The two butterfly valves, which are mounted in a two-piece, die-cast aluminum housing called the throttle body, control air flow to the engine. The butterfly valves, or throttle valves, are identical in design to the throttle plates of a conventional carburetor and are actuated by a similar linkage and pedal cable arrangement.
See Figure 5
The two fuel injector nozzles, which are mounted in the throttle body, are electro-mechanical devices that meter and atomize the fuel delivered to the engine. The injector valve bodies consist of a solenoid actuated pintle and needle valve assembly. An electrical control signal from the EEC electronic processor activates the solenoid, causing the pintle to move inward off its seat, allowing fuel to flow. The fuel flow through the injector is controlled by the amount of time the injector solenoid holds the pintle off its seat.
See Figure 6
The fuel pressure regulator is mounted on the throttle body. The regulator smooths out fuel pressure drops from the fuel pump. It is not sensitive to back pressure in the return line to the tank.
A second function of the pressure regulator is to maintain fuel supply pressure upon engine and fuel pump shut down. The regulator acts as a check valve and traps fuel between itself and the fuel pump. This promotes rapid start ups and helps prevent fuel vapor formation in the lines, or vapor lock. The regulator makes sure that the pressure of the fuel at the injector nozzles stays at a constant 39 psi (265 kPa).
See Figure 7
A Schrader-type diagnostic pressure valve is located at the top of the throttle body. This valve can be used by service personnel to monitor fuel pressure, bleed down the system pressure prior to maintenance and to bleed out air which may have been introduced during assembly or filter servicing. A special Ford Tool (T80L-9974-A) is used to accomplish these procedures.
Cold Engine Speed Control (Throttle Stop Cam Positioner)-V8 engine
The cold engine speed control serves the same purpose as the fast idle speed device on a carbureted engine, which is to raise engine speed during cold engine idle. A throttle stop cam positioner is used on the V8 engine. The cam is positioned by a bimetal spring and an electric heating element. The cold engine speed control is attached to the throttle body. As the engine heats up, the fast idle cam on the cold engine speed control is gradually repositioned by the bimetal spring, heating element and EEC computer until normal idle speed is reached. The EEC computer automatically kicks down the fast idle cam to a lower step (lower engine speed) by supplying vacuum to the automatic kickdown motor which physically moves the high speed cam a predetermined time after the engine starts.Idle Speed Controller (ISC) DC Motor Actuator-V6 engine
See Figure 8
The DC motor actuator controls idle speed by modulating the throttle lever. The resulting airflow regulation permits the desired engine rpm for warm engine operation, as well as the additional engine speed required during cold engine idle. An Idle Tracking Switch (ITS), integral to the DC motor, determines when the throttle lever has contacted the actuator, thereby signaling the need to control engine rpm. The DC motor extends or retracts a linear shaft through a gear reduction system. The motor direction is determined by the polarity of the applied voltage.
This sensor is attached to the throttle body and is used to monitor changes in throttle plate position. The throttle position sensor sends this information to the computer, which uses it to select proper air/fuel mixture, spark timing and EGR control under different engine operating conditions.