See Figures 1 through 7
IDLE SPEED ADJUSTMENT
- Remove the air cleaner and plug the vacuum lines.
- Set the parking brake and block the wheels.
- Connect a tachometer according to the manufacturer's instructions.
- Run the engine to normalize underhood temperatures.
- Check, and if necessary, reset the ignition timing.
- Make certain that the choke plate is fully open.
- Place the manual transmission in neutral; the automatic in Drive. Block the wheels.
- Turn the solenoid adjusting screw in or out to obtain the specified idle speed. The idle speed is the higher of the two rpm figures on the underhood specification sticker.
- Disconnect the solenoid lead wire. Place the automatic transmission in neutral.
- Turn the solenoid off adjusting screw to obtain the solenoid off rpm. This is the lower of the two rpm figures on the underhood specifications sticker.
- Connect the solenoid lead wire and open the throttle slightly to allow the solenoid plunger to extend.
- Stop the engine, replace the air cleaner and connect the vacuum lines. Check the idle speed. Readjust if necessary with the air cleaner installed.
- Block the wheels and apply parking brake.
- Run engine until normal operating temperature is reached.
- Place the vehicle in Park or Neutral, A/C in Off position, and set parking brake.
- Remove air cleaner.
- Disconnect and plug decel throttle control kicker diaphragm vacuum hose.
- Connect a slave vacuum hose from an engine manifold vacuum source to the decel throttle control kicker.
- Run engine at approximately 2,500 rpm for 15 seconds, then release the throttle.
- If decel throttle control rpm is not within plus or minus 50 rpm of specification, adjust the kicker.
- Disconnect the slave vacuum hose and allow engine to return to curb idle.
- Adjust curb idle, if necessary, using the curb idle adjusting screw.
- Rev the engine momentarily, recheck curb idle and adjust if necessary.
- Reconnect the decel throttle control vacuum hose to the diaphragm.
- Reinstall the air cleaner.
IDLE MIXTURE ADJUSTMENT
For this procedure, Ford recommends a propane enrichment procedure. This requires special equipment not available to the general public. In lieu of this equipment the following procedure may be followed to obtain satisfactory idle mixture.
- Block the wheels, set the parking brake and run the engine to bring it to normal operating temperature.
- Disconnect the hose between the emission canister and the air cleaner.
- On engines equipped with the Thermactor air injection system, the routing of the vacuum lines connected to the dump valve will have to be temporarily changed. Mark them for reconnection before switching them.
- For dump valves with one or two vacuum lines at the side, disconnect and plug the lines.
- For dump valves with one vacuum line at the top, check the line to see if it is connected to the intake manifold or an intake manifold source such as the carburetor or distributor vacuum line. If not, remove and plug the line at the dump valve and connect a temporary length of vacuum hose from the dump valve fitting to a source of intake manifold vacuum.
- Remove the limiter caps from the mixture screws by CAREFULLY cutting them with a sharp knife.
- Place the transmission in neutral and run the engine at 2500 rpm for 15 seconds.
- Place the automatic transmission in Drive; the manual in neutral.
- Adjust the idle speed to the higher of the two figures given on the underhood sticker.
- Turn the idle mixture screws to obtain the highest possible rpm, leaving the screws in the leanest position that will maintain this rpm.
- Repeat steps 7 through 10 until further adjustment of the mixture screws does not increase the rpm.
- Turn the screws in until the lower of the two idle speed figures is reached. Turn the screws in 1 / 4 turn increments each to insure a balance.
- Turn the engine off and remove the tachometer. Reinstall all equipment.
Rough idle, that cannot be corrected by normal service procedures on 1977 and later models, may be cause by leakage between the EGR valve body and diaphragm. To determine if this is the cause:
- Tighten the EGR bolts to 15 ft.lb. Connect a vacuum gauge to the intake manifold.
- Lift to exert a sideways pressure on the diaphragm housing. If the idle changes or the reading on the vacuum gauge varies, replace the EGR valve.