Idle Air Bleed Valve Adjustment

Fig. 7 Idle air bleed valve cover removal. E2MC-ME & E4MC-ME carburetors:

Fig. 8 Idle air bleed valve identification. E2MC-ME & E4MC-ME carburetors:

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 vacuum hoses as directed by underhood vehicle emissions label.
3. Start engine and run until it reaches normal operating temperature and dwell reading begins to fluctuate. Adjustments must be made with system operating in ``Closed Loop'' mode, indicated by a fluctuating dwell reading. It is essential that coolant temperature and oxygen sensors be at operating temperature during adjustments. Some engines may enter ``Open Loop'' mode at idle (indicated by fixed dwell reading), due to cooling of oxygen sensor. In this case, place transmission in neutral and run engine at fast idle until dwell reading begins to fluctuate.
4. Place transmission in Drive (manual transmission in Neutral) and check curb idle speed. If curb idle speed is not within specifications on models equipped with Idle Speed Control (ISC) refer to ``Computer Command Control (C3)'' chapter in the Emission Controls Section for troubleshooting procedure, and ``Idle Speed Control (ISC) Adjustment'' in the Carburetor section, for adjustment procedure.
5. With engine at specified curb idle speed, dwell meter should indicate a fluctuating reading with a 10°-50° range.
6. If dwell reading is within specifications, mixture adjustment is correct.
7. If dwell reading is not within specifications, remove cover from idle air bleed valve, Fig. 7:
a. Stop engine and cover carburetor air intake, vents, etc. to prevent metal chips from entering engine.
b. Carefully center a No. 35 drill (.110 inch) on one of the rivets securing bleed valve cover. Drill only enough to remove rivet head, then repeat with remaining rivet.
c. Drive rivet stems out of air bleed valve tower with a small punch. Remove and discard cover.
d. Remove pieces of rivet from bleed valve tower, then blow out any dirt or metal chips that may have entered bleed valve cavity.
8. Examine top of air bleed valve for an identification letter, Fig. 8.
9. If no letter is stamped on valve, proceed to Mixture Adjustment A. If a letter is stamped on valve, proceed to Mixture Adjustment B.