Idle Mixture Adjustment

The dwell signal from the Computer Command Control (C-3) system is used to adjust idle mixture. Idle mixture should only be adjusted if carburetor is overhauled, or if "Diagnostic Checks", outlined previously, indicate the carburetor as source of complaint. On 1981-82 models, the Mixture Control (MC) solenoid should not be adjusted.

1. Connect dwell meter to test lead in MC solenoid harness (usually a green wire) and set meter on 6 cylinder scale. Connect tachometer to engine following manufacturer's instructions.
2. Disconnect and plug purge hose at vapor canister and other hoses as directed by underhood Emission Control Information Label.
3. Start engine and run at fast idle until it reaches normal operating temperature, and dwell reading begins to fluctuate.
4. Place transmission in drive (manual transmission in neutral) and adjust curb idle speed to specifications with throttle stop screw.
5. Observe dwell meter, if reading fluctuates within 10~50 range, mixture adjustment is correct. Proceed to step 12.
6. If reading does not fluctuate, or if reading is not within 10~-5O range, remove lug sealing mixture screw as outline in "Concealment Plug Removal".
7. Reinstall carburetor with air cleaner off and hoses plugged as in step 2. Turn mixture screw in (clockwise) until lightly seated, then back screw out 2 turns.
8. Start engine and run until it reaches normal operating temperature (dwell reading fluctuates).
9. Place transmission in drive (manual transmission in neutral). Adjust idle mixture screw, turning screw in small increments, to obtain a fluctuating dwell reading within 25~-35 range, as close to 30 as possible.
10. If unable to obtain specified dwell reading, repair carburetor idle circuit.
11. Install air cleaner and adjust curb idle speed to specifications with throttle sto1 screw.
12. If equipped with A/C:
a. Disconnect wiring harness connector to A/C compressor and place A/C control in on position.
b. Momentarily open throttle to allow solenoid plunger to extend, then adjust A/C idle speed to specifications with solenoid plunger screw.
c. Turn 0N A/C and connect wiring harness connector to compressor.
13. Stop engine. Reconnect vacuum hoses ti proper fittings and seal mixture screw cavity with RTV sealer.