For 1990-2009 cars

# IDLE MIXTURE ADJUSTMENT SUPPLEMENT TO SERVICE MANUAL

THE FOLLOWING SUBJECT PROCEDURE WAS OMITTED FROM SECTION 6C3 OF THE 1982 CITATION/CELEBRITY SHOP MANUAL (ST-365-82). PLEASE MAKE NOTE OF THIS PROCEDURE IN YOUR COPY OF THE SHOP MANUAL. IDLE MIXTURE ADJUSTMENT CARBURETOR PRE-SET PROCEDURE: 1.REMOVE CARBURETOR FROM ENGINE FOLLOWING NORMAL SERVICE PROCEDURES TO GAIN ACCESS TO PLUG COVERING THE IDLE MIXTURE NEEDLE. REMOVE PLUG FOLLOWING PROCEDURE IN SHOP MANUAL, (FIGURE 6C3-16). TURN MIXTURE SCREW IN UNTIL LIGHTLY SEATED AND BACK OUT SPECIFIED TURNS (SEE MIXTURE ADJUSTMENT SPECIFICATIONS). 2.REMOVE VENT STACK-SCREEN ASSEMBLY TO GAIN ACCESS TO LEAN MIXTURE SCREW. (BE SURE TO REINSTALL VENT STACK AFTER ADJUSTMENT.) 3.TURN LEAN MIXTURE SCREW IN UNTIL LIGHTLY BOTTOMED AND BACK OUT SPECIFIED TURNS (SEE MIXTURE ADJUSTMENT SPECIFICATIONS, FIGURE 6C3-36) 4.REINSTALL CARBURETOR ON ENGINE: A.DO NOT INSTALL AIR CLEANER AND GASKET. B.DISCONNECT THE BOWL VENT LINE AT CARBURETOR AND DISCONNECT AND PLUG VACUUM HOSE TO THE "TEE" IN THE BOWL VENT LINE (IF USED). C.DISCONNECT THE EGR VALVE AND CANISTER PURGE AT THE CARBURETOR (LOCATION C) AND CAP THE CARBURETOR PORT. D.REMOVE THE SECONDARY VACUUM BREAK THERMAL VACUUM SWITCH FROM THE AIR CLEANER (CLIP MOUNTED). DISCONNECT THE VACUUM HOSE CONNECTING THE THERMAL VACUUM SWITCH TO THE THERMOSTATIC AIR CLEANER (TAC) SENSOR AND CAP THE OPEN PORT ON THE THERMAL VACUUM SWITCH. VACUUM HOSES FROM THE THERMAL VACUUM SWITCH TO THE SECONDARY VACUUM BREAK, CARBURETOR AND T.P.S. SHOULD REMAIN CONNECTED. E.CONNECT TACH/DWELL; CONNECT DWELL METER TO THE MIXTURE CONTROL SOLENOID TEST LEAD (GREEN CONNECTOR). SET DWELL METER TO 6-CYLINDER POSITION. CONNECT THE TACHOMETER TO DISTRIBUTOR TACH LEAD (BROWN CONNECTOR). F.BLOCK DRIVE WHEELS. G.PLACE TRANSMISSION IN PARK (AUTOMATIC TRANSMISSION) OR NEUTRAL (MANUAL TRANSMISSION) AND SET THE PARKING BRAKE. H.SEE MIXTURE ADJUSTMENT PROCEDURE. MIXTURE ADJUSTMENT PROCEDURE SEE "PRE-SET PROCEDURE" 1.RUN ENGINE ON HIGH STEP OF FAST IDLE CAM UNTIL ENGINE COOLING FAN STARTS TO CYCLE. (AT LEAST THREE MINUTES AND UNTIL IN CLOSED LOOP. 2.RUN ENGINE AT 3,000 RPM AND ADJUST THE LEAN MIXTURE SCREW (FIG. 6C3-4) SLOWLY IN SMALL INCREMENTS ALLOWING TIME FOR DWELL TO STABILIZE AFTER TURNING THE SCREW TO OBTAIN AN AVERAGE DWELL OF 35F. IF DWELL IS TOO LOW, BACK SCREW OUT; IF TOO HIGH, SCREW IT IN. IF UNABLE TO ADJUST TO SPECIFICATIONS, INSPECT MAIN METERING CIRCUIT FOR LEAKS, RESTRICTIONS, ETC. THE DWELL READING OF THE M/C SOLENOID IS USED TO DETERMINE CALIBRATION AND IS SENSITIVE TO CHANGES IN FUEL MIXTURE CAUSED BY HEAT, AIR LEAKS, ETC. WHILE IDLING IT IS NORMAL FOR THE DWELL TO INCREASE AND DECREASE FAIRLY CONSTANTLY OVER A RELATIVELY NARROW RANGE, SUCH AS 5F. HOWEVER, IT MAY OCCASIONALLY VARY BY AS MUCH AS 10-15F MOMENTARILY DUE TO TEMPORARY MIXTURE CHANGES. THE DWELL READING SPECIFIED IS THE AVERAGE OF THE MOST CONSISTENT VARIATION. THE ENGINE MUST BE ALLOWED A FEW MOMENTS TO STABILIZE AT IDLE OR 3,000 RPM AS APPLICABLE BEFORE TAKING A DWELL READING. 3.RETURN TO IDLE AND ADJUST IDLE SPEED TO 700 RPM IN PARK WITH COOLING FAN IN OFF CYCLE. 4.ADJUST IDLE MIXTURE SCREW TO OBTAIN AN AVERAGE DWELL OF 25F WITH COOLING FAN IN OFF CYCLE. IF READING IS TOO LOW, BACK SCREW OUT. IF TOO HIGH, TURN IT IN. ALLOW TIME FOR READING TO STABILIZE AFTER EACH ADJUSTMENT. ADJUSTMENT IS VERY SENSITIVE. MAKE FINAL CHECK WITH ADJUSTMENT TOOL REMOVED. IF UNABLE TO ADJUST TO SPECIFICATIONS, INSPECT IDLE SYSTEM FOR LEAKS, RESTRICTIONS, ETC. 5.DISCONNECT M/C SOLENOID WHILE COOLING FAN IS IN OFF CYCLE AND CHECK FOR AN RPM CHANGE OF AT LEAST 50 RPM. IF RPM DOES NOT CHANGE ENOUGH, INSPECT IDLE AIR BLEED CIRCUIT FOR RESTRICTIONS, LEAKS, ETC. 6.RUN ENGINE AT 3,000 RPM FOR A FEW MOMENTS AND NOTE DWELL READING. DWELL SHOULD BE VARYING WITH AN AVERAGE READING OF 35F. IF NOT AT 35F AVERAGE DWELL: RESET LEAN MIXTURE SCREW PER STEP 2. THEN RESET IDLE DWELL PER STEP 4. IF AT AVERAGE DWELL: RECONNECT SYSTEMS DISCONNECTED EARLIER (PURGE AND VENT HOSES, EGR VALVE, ETC.), REINSTALL VENT SCREEN AND SET IDLE SPEED(S) PER EMISSION CONTROL INFORMATION LABEL ON CAR. IT IS NOT NECESSARY TO REPEAT "SYSTEMS PERFORMANCE CHECK" (SECTION 6E1) AFTER PROPER ADJUSTMENT OF CARBURETOR.

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