Ford Tempo/Topaz 1984-1994 Repair Guide

Idle Mixture



The following procedure is not recommended for DIYer's. The carburetor must be removed in order to gain access to the tamper resistant plugs that cover the mixture screw. It should also be noted that a propane enrichment kit will be needed to perform this operation.

  1. Remove the carburetor from the engine and drain any remaining fuel from the fuel bowl.
  3. Drill a 3 / 32 in. (2.4mm) hole through both the steel and the plastic tamper resistant plugs.
  5. Using a hack saw, cut through the metal cup in a lengthwise direction and insert a suitable tool to twist the metal so as to expose the inner tamper resistant plug.
  7. Install a screw extractor into the hole and remove the steel and or plastic plugs. Reinstall the carburetor assembly on the engine. Adjust the idle speed mixture as follows:
    1. Connect a tachometer and timing light to the engine. Make sure that the hot idle compensator is closed, if equipped.
    3. Disconnect the fuel evaporative system purge hose at the air cleaner assembly and plug the fitting on the air cleaner.
    5. Disconnect the fresh air duct from the air cleaner and insert the hose from the propane tank 3 / 4 of the way into the air cleaner duct. Be sure to leave all vacuum lines attached to the air cleaner. The air cleaner can be positioned off to the side, but it must be complete and in place when making this adjustment.
    7. If the emission system is equipped with air injection, the air injection dump valves should be altered as follows; If the valve has 2 vacuum fittings, disconnect and plug the hoses. If there is only 1 vacuum fitting, disconnect and plug the hose and then run another vacuum hose from the fitting to manifold vacuum.
    9. If equipped with an automatic transmission, disconnect and plug the vacuum line at ISC motor. Connect a vacuum pump to the ISC and apply enough vacuum to retract the ISC plunger clear of the throttle linkage.
    11. Remove the PCV valve from the valve cover and allow it to draw fresh air. Run the engine briefly at 2500 rpm.
    13. With the engine at normal operating temperature and idling, and the transmission in NEUTRAL (manual transaxle) or DRIVE (automatic transaxle), begin to slowly open the valve on the propane bottle and watch for the engine rpm to rise.The propane bottle must be held in a vertical position during this adjustment.
    15. When the engine rpm begins to drop off, note the maximum speed gained. If the gain is within the rpm gain range do not adjust.
    17. If the maximum speed gain was too high, turn the mixture screw counterclockwise slightly to richen. If the maximum speed gain was to low, turn the mixture screw clockwise slightly to lean out.After turning the mixture screw, allow 15 seconds for idle to stabilize before turning the screw again.
    19. Turn the mixture screw left or right while repeating the propane enrichment procedure. Continue until the rpm level falls within the factory reset rpm specifications.
    21. Once the desired rpm levels have been reached, connect any hoses which were unfastened earlier. Adjust the idle speed, if needed. Remove the test equipment from the engine compartment.

      1984-85 2.3 1 bbl HO (manual transaxle)-RPM Gained: 60-100-Reset RPM: 80.
      1984-85 2.3 1 bbl HO2.3L 1 bbl HO (automatic transaxle Fed.)-RPM Gained: 150-200-Reset RPM: 175.
      1984-85 2.3 1 bbl HO2.3L 1 bbl HSC (automatic transaxle Cal.)-RPM Gained: 160-240-Reset RPM: 200.
      1986-87 2.3L 1 bbl OHC (manual transaxle-RPM Gained: 60-100-Reset RPM: 80.
      1986-87 2.3L 1 bbl OHC (automatic transaxle Fed.)-RPM Gained: 150-20-Reset RPM: 175.
      1986-87 2.3L 1 bbl OHC (automatic transaxle Cal.)-RPM Gained: 160-240-Reset RPM: 200.




Idle mixture adjustments are not possible or necessary on the fuel injected engines. This is because the engine management system installed in theses vehicles monitors and adjusts the mixture as a normal part of its functioning.