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may experience an incident of engine misfire during certain vehicle operating conditions. The misfire may occur when the vehicle is operated between 80 – 112 KPH (50 – 70 MPH) and under light loading conditions, e.g. slight uphill road grades. This condition may occur at all ambient conditions, but is more noticeable when ambient conditions are less than 0°C (32°F). If the vehicle is equipped with On-Board Diagnostic (OBD), a MIL illumination may also have occurred due to Diagnostic Trouble Code (DTC) P0300 – Multiple Cylinder Misfire. Various single cylinder misfire DTC’s may also be present. If the frequency of misfire is high the Powertrain Control Module (PCM) may place the engine in “Limp-In” mode. The misfire condition may be caused by one or more engine exhaust valves that are slow to close. Late closure of an exhaust valve may be the result of no valve rotation and associated build up of carbon on the exhaust valve stem. This condition may occur when the engine is not allowed to run at engine RPM’s that are greater than 3,200 RPM. At 3,200 RPM or higher the engine exhaust valves will rotate if not impeded by high carbon deposits. Low engine RPM’s and high carbon deposits are associated with short trip driving where the vehicle engine is not allowed to fully warm to normal engine operating temperatures. Cold ambient temperatures will increase engine warm-up time and add to the opportunity of carbon deposit build-up on the stem of the engine exhaust valve. Verify that an engine misfire condition is present. Use of the DRBIII(R) during a road test, or a Co-Pilot data recording, may help to determine engine misfire and misfire counts. If carbon deposit accumulation is severe, then a cylinder leak down test may detect one or more cylinders leaking greater than 15%. Save any misfire DTC Freeze Frame Data that was stored for later misfire correction verification. Verify that the engine misfire condition is not caused by faulty engine mechanical or electrical components. If the engine mechanical and electrical systems are operating properly perform

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DESCRIPTION Some vehicles may experience a body vibration when driving approximately 55mph. This symptom is due to the characteristics of the No. 3 & No. 4 engine mounts. Modified No. 3 & No. 4 engine mounts have been established for service only. Customers having this concern should have their vehicle repaired using the following repair procedure. REPAIR PROCEDURE IMPORTANT NOTE: • This repair should only be performed if all tires and rims are confirmed to be in balance and all suspension components are in proper working condition. • Notify customers that use of the modified mounts will reduce vibration at cruising speed but may increase vibration at idle. NOTE: Because idle vibration may increase, it is highly recommended to continue using mass production mounts for all other service concerns. 1. Verify concern. 2. Replace the No. 3 & 4 engine mounts with service parts according to the appropriate Workshop Manual section 01-10 ENGINE REMOVAL/INSTALLATION. 3. Center the new engine mounts as outlined in ENGINE MOUNT CENTERING PROCEDURE. 4. Verify repair. ENGINE MOUNT CENTERING PROCEDURE No. 1, No. 3 and No. 4 Engine Mount Adjustment 1. Warm up the engine. 2. Raise and support vehicle on a hoist. 3. Remove engine under cover. 4. Lower the vehicle until the front tires lightly touch the ground. 5. Secure the engine and transaxle using an engine jack and attachment as instructed in No.3 Engine Mount And No.4 Engine Mount Rubber Installation Note in appropriate Workshop Manual, section 01-10 MECHANICAL. 6. Remove two bolts from No. 3 engine mount bracket. REMOVE THE BOLTS 7. Lift engine using jack until No.3 engine mount is lifted slightly from vehicle body. NOTE: • Do not raise engine too much or A/C pipe damage may occur. 8. Move the engine mount rubber or engine until installation hole on the vehicle body aligns with hole in the engine mount bracket. ENGINE MOUNT BRACKET 1532c SHOWN BEFORE ALIGNING THE HOLES SHOWN AFTER ALIGNING THE HOLES 9. Lower the jack and tighten bolts on No. 3 engine mount bracket. Tightening torque: 55.0-77.3 ft-lbf (74.5-04.9 N.m) NOTE: 10. With engine supported as described in STEP 5, remove four (4) nuts and two (2) bolts from No. 4 engine mount top plate. Remove top plate. NOTE: 11. Lift engine again using jack until No.4 engine mount is lifted slightly from vehicle body. NOTE: 12. With top plate of No. 4 engine mount removed, move engine mount bottom plate or engine until all four (4) installation studs on the vehicle align with the engine mount holes. • Do not allow the engine mount bracket to be misaligned. • To access the mount, remove battery box. • Do not raise engine too much or A/C pipe damage may occur. ALIGN THE 4 STUDS IN THE PLATE HOLES 13. Place top plate back on and tighten No. 4 engine mount bracket nuts and bolts to torque indicated. Tightening torque: A.32.5-45.0 ft-lbf (44.0-61.0 N.m) B.61.1-86.7 in-lbf (6.9-9.8 N.m) TIGHTEN BOLTS IN SEQUENCE SHOWN 1532e 14. Lift engine again using jack and loosen the two bolts on the No. 1 engine mount rubber until slightly loose on the No. 1 engine mount rubber.

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CONDITION & POSSIBLE CAUSE CORRECTION Hard Starting Binding carburetor linkage Eliminate binding Binding choke linkage Eliminate binding Binding choke piston Eliminate binding Restricted choke vacuum Check vacuum lines for blockage Worn or dirty needle valve and seat Clean carburetor, see ENGINE PERFORMANCE Float sticking Readjust or replace float see the ENGINE PERFORMANCE section Incorrect choke adjustment Reset choke adjustment see ENGINE PERFORMANCE Defective coil Replace coil Improper spark plug gap Regap spark plugs Incorrect ignition timing Reset ignition timing see ENGINE PERFORMANCE Detonation Over-advanced ignition timing Reset ignition timing see ENGINE PERFORMANCE Defective spark plugs Replace spark plugs Fuel lines clogged Clean fuel lines EGR system malfunction Check and repair EGR system PCV system malfunction Repair PCV system Vacuum leaks Check and repair vacuum system Loose fan belts Tighten or replace fan belts, see ENGINE PERFORMANCE Restricted airflow Remove restriction Vacuum advance malfunction Check distributor operation Dieseling Binding carburetor linkage Eliminate binding Binding throttle linkage Eliminate blinding Binding choke linkage or fast idle cam Eliminate binding Defective idle solenoid Replace idle solenoid see ENGINE PERFORMANCE Improper base idle speed Reset idle speed, see see ENGINE PERFORMANCE Incorrect ignition timing Reset ignition timing see ENGINE PERFORMANCE Incorrect idle mixture setting Reset idle mixture, see ENGINE PERFORMANCE Faulty Acceleration Incorrect ignition timing Reset ignition timing see ENGINE PERFORMANCE Engine cold and choke too lean Adjust choke and allow engine to warm-up Defective spark plugs Replace spark plugs Defective coil Replace coil

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Remove the lower engine splash shield. 4. Drain the cooling system. For additional information, refer to Section 03-03. 5. Disconnect the oil pressure switch and power steering pump connectors. 6. Rotate the belt tensioner and remove the serpentine belt from the power steering pump pulley. 7. NOTE: The lower forward bolt cannot be removed. Remove the power steering pump retainers and secure the pump out of the way. 8. Remove the four front oil pan-to-front engine cover retaining bolts. 9. Disconnect the crankshaft position sensor (CPS) connector and the sensor wiring from the harness locator. 10. Remove the lower radiator hose from the support on the fan shroud. 11. Lower the vehicle. 12. Recover the refrigerant from the A/C system. For additional information, refer to Section 12-00. 13. Remove the upper radiator hose. 14. Disconnect the cooling fan wiring connector at the right side of the fan shroud. Remove the two shroud retainers and rotate the lower fan shroud on top of the upper shroud. Remove the electric cooling fan and fan shroud. 15. Remove the fan clutch assembly from the water pump pulley hub using Fan Clutch Nut Wrench T84T-6312-D and Fan Clutch Pulley Holder T94T-6312-AH. 16. Remove the serpentine bolt. 17. Remove the water pump pulley. 18. Remove the serpentine belt idler pulley from the front engine cover. 19. Disconnect the camshaft position sensor (CMP) (6B288) connector and the ignition coil connectors. Remove the left coil and bracket assembly and position the assembly out of the way.

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Subject: Models: Low Engine Coolant Level Indicator Always On (Diagnose Low Coolant Level System Operation/Check Sensor for Oil Contamination) 2000-2002 Buick Century, Regal 2000-2001 Chevrolet Lumina 2000-2002 Chevrolet Impala, Monte Carlo 2000-2002 Pontiac Grand Prix 2000-2002 Oldsmobile Intrigue Condition Some customers may comment that the low engine coolant level indicator is always illuminated. Cause The cause of this condition may be due to engine oil contaminating the coolant. Possible sources of oil contamination are internal engine leaks, improper service procedures, or the addition of some types of anti-leak additives to the cooling system. Once in the coolant, the oil leaves deposits on the level sensor creating an insulating film. This film results in a false activation of the coolant level indicator. Correction Diagnose low coolant level system operation and check the sensor for oil contamination using the procedure listed below. Important: No coolant supplements should be used in GM cooling systems, other than what is approved and recommended by GM. The use of “aftermarket” over-the-counter sealing and cooling supplements may affect the operation of the low coolant level sensor. Discoloration of the coolant recovery bottle is normal and does not necessarily indicate that coolant contamination is present. Flush cooling system only when instructed by this bulletin. 1. Verify that the coolant is at proper level in the radiator and the coolant recovery bottle. If the coolant is low, add proper amount of 50/50 water and DEX-COOL® mixture. If the low coolant light operates properly, diagnose the cooling system for loss of coolant as outlined in SI. DO NOT proceed further with this bulletin. 2. Remove the low coolant level sensor. Refer to Coolant Level Module Replacement in the Engine Cooling sub-section. 3. With the key on, the engine off and the coolant level sensor disconnected from the vehicle wiring harness, observe the low coolant light: • Light is on — Chassis wiring or instrument cluster concern. Follow the appropriate diagnostic information in SI. • Light is out — Proceed to Step 4.