See Figures 1 and 2
The fuel charging throttle body mounts to the conventional carburetor pad of the intake manifold. Mounted above the throttle body is the fuel charging main body. This fuel charging assembly is comprised of six types of components which precisely allocate fuel and air to the engine. The result is an ideal ratio for providing performance and economy, while controlling exhaust emissions. The six types of components are:
Butterfly Valves (Air Flow Control)
See Figure 3
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 4
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 5
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.
See Figure 6
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)-8-302 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 8-302 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-6-232 engine
See Figure 7
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.
REMOVAL & INSTALLATION
Fuel Charging Assembly
The automatic transmission throttle valve lever must be adjusted whenever the fuel charging assembly is removed for service or replacement.
- Remove the air cleaner assembly.
- Relieve pressure from the fuel system at the diagnostic valve on the fuel charging assembly, as described above.
- Disconnect the throttle cable and transmission throttle valve lever.
- Disconnect the fuel, vacuum and electrical connections.
- Remove the fuel charging assembly retaining nuts.
- Remove the fuel charging assembly, spacer (if so equipped), and mounting gasket(s) from the intake manifold.
If the fuel charging assembly is to be disassembled or overhauled, proceed to the following sections which cover the Main Body and the Throttle Body.To install:
- Clean the gasket mounting surfaces of the intake manifold, spacer and the fuel charging assembly.
- Position the spacer (if applicable) between two new gaskets and place the spacer and gaskets on the intake manifold. Position the fuel charging assembly on the gasket.
- Secure the fuel charging assembly with the attaching nuts. Snug the nuts, then alternately tighten them in a criss-cross pattern to 10 ft. lbs.
- Connect the fuel and vacuum lines, and electrical connectors.
- Connect the throttle cable and transmission throttle valve lever.
- Start the engine and check for leaks. Adjust engine idle speed, if necessary.
- Install the air cleaner assembly.
See Figures 8, 9, 10, 11, 12 and 13
- Remove the air cleaner mounting stud, in order to separate the main (upper) body from the throttle body.
- Turn the fuel charging assembly over and remove the four screws from the bottom of the throttle body.
- Separate the throttle body (lower section) from the main body.
- Remove the old 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, gasket and O-ring.
- Disconnect 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(s). Push in on the harness tabs to remove it from the upper body.
- Remove the fuel injector retaining fastener. Remove the injector retainer.
- Pull the injectors, one at a time, from the upper body. Mark the injectors for identification, since 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 cavity in the throttle body.
- Using a wrench, unscrew the fuel pressure diagnostic valve assembly.
See Figures 14 and 15
- Note the position of the index mark on the choke cap housing. Remove the choke cap retainer screws or rivets.
- Remove the choke cap retaining ring, choke cap and gasket, if so equipped.
- Remove the thermostat lever screw and lever, if so equipped.
- Remove the fast idle cam assembly and control rod positioner, if so equipped.
The Idle Speed Controller (ISC) system is used on the 6-232 engine, in place of the choke pulldown system.
- Hold the control diaphragm cover in position, if so equipped, and remove the two mounting screws. Carefully remove the cover, spring and pull down diaphragm.
- Remove the fast idle retaining nut, fast idle cam adjuster lever, fast idle lever, spring and E-clip.
- Remove the throttle position sensor connector bracket fastener. Mark the throttle body and throttle position sensor for correct installation position. Remove the throttle position sensor retaining screws and slide the sensor off of the throttle shaft.
- Remove the throttle positioner mounting bolt and remove the throttle positioner, if so equipped. (If equipped instead with an ISC DC motor actuator, remove the mounting bolts and the motor.)
- Perform any necessary cleaning or repair.
- Install the fuel pressure diagnostic valve assembly. Tighten the valve to 48-84 inch lbs. and the cap to 5-10 inch lbs.
- Lubricate new injector O-rings with a light grade oil and install one on each injector. Install the injectors in their appropriate choke or throttle side position. Use a light, twisting, pushing motion to seat the injectors.
- Install the injector retainer and tighten the fastener to 30-60 inch lbs.
- Install the injector wiring harness and snap into position. Tighten the harness retaining screw(s) to 8-10 inch lbs.
- Snap the electrical connectors into position on the injectors. Lubricate a new fuel pressure regulator O-ring with light oil and install the O-ring and new gasket on the regulator. Install the regulator and tighten the retaining screws to 27-40 inch lbs.
- Install the throttle positioner or ISC DC motor onto the throttle body. Tighten the mounting bolt(s) to 32-44 inch lbs.
- Hold the throttle sensor (potentiometer) with the location identification mark (see step 7, above) 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 11-16 inch lbs.
- Install the throttle position sensor connector bracket fastener and tighten to 18-22 inch lbs.
- Install the E-clip, fast idle lever and spring, fast idle adjustment lever and fast idle retaining nut, if so equipped. Tighten the retaining nut to 16-20 inch lbs.
- Install the pull down diaphragm, spring and cover, if so equipped. Hold the cover in position and tighten the retaining screws to 13-19 inch lbs.
- Install the fast idle control rod positioner, fast idle cam and thermostat lever, if so equipped. Tighten the retaining screw to 13-19 inch lbs.
- Install the choke cap gasket, if so equipped, and the choke cap and retaining ring. Be sure that the choke cap bimetal spring is properly inserted between the fingers of the thermostat lever.
- Install the choke cap retaining screws loosely and rotate the cap so that the index mark is properly aligned. Tighten the screws 13-18 inch lbs. If equipped with rivets, install new rivets and snug them with the rivet gun. Do not break off the rivets until the choke cap's index mark is properly aligned.
- Install a new gasket between the main body and the throttle body. Place the throttle body on the main body and install the four retaining screws loosely. Install the air cleaner stud and tighten to 70-95 inch lbs. Tighten the four retaining screws to 27-40 inch lbs.