Air Fuel Mixture

Idle Set Connector:

Monitoring M/C Duty Cycle:

Engine at operating temperature, air cleaner removed and Inlet Temperature Control (ITC) valve vacuum hose plugged.

1. Set the parking brake and block the drive wheels.
2. Make sure the transmission is in park (A/T), or neutral (M/T).
3. Remove idle mixture adjusting screw plug.

NOTE: It may be necessary to remove the carburetor to do this.

4. Remove the idle mixture screw and inspect, replace if damaged or bent.
5. Re-install idle mixture screw and turn in until lightly seated. Do not overtighten.
6. Back the screw out the following number of turns:
Three turns from fully closed (M/T)
Two turns from fully closed (A/T)
7. Disconnect and plug the distributor vacuum hose, canister purge hose, and EGR vacuum hose.
8. Be sure all accessories are turned OFF (heater blower, A/C, electric defroster, lights, etc.)
9. Disconnect idle set (idle switch) connector "M17" from "M8", located on the engine compartment wiring harness leading to the carburetor.

NOTE: When the idle set connector is disconnected, the "Check Engine" light will come on.

10. Start engine and run at 2,000 rpm for 1 minute, then idle.
11. Adjust the throttle adjusting screw until the engine is idling at:
750 rpm (M/T)
1,000 rpm (A/T)
12. Connect a dwell meter to the mixture control solenoid duty monitor connector, and ground. Set meter to 6 cyl. scale.
13. Adjust idle mixture adjusting screw so that dwellmeter reading is varying at approx. 30 degrees on the average. If dwell becomes fixed while adjusting, the Oxygen sensor has cooled off. Run engine at 2,000 rpm for 1 minute or until dwell begins to vary (indicating the Oxygen sensor is hot), then continue with this step.
14. Re-connect the idle set connector. The "Check Engine" light will go out.
15. Readjust idle speed as in step 11.
16. Readjust the dashpot.
17. Install a new idle mixture adjusting plug, and seal with adhesive thread locking compound.

NOTE:If vehicle is equipped with air conditioning, the following additional steps must also be performed.

18. Turn the A/C on, and set to "MAX COLD". Turn A/C blower on high.
19. Adjust the Fast Idle Control Diaphragm (FICD) adjusting screw at the tip of the throttle lever to set the fast idle speed to:
850 rpm (M/T)
980 rpm (A/T)