2007 Jeep Liberty Owner's Manual - Page 324

324 MAINTAINING YOUR VEHICLE Special tools are required to properly measure tension and to restore belt tension to factory specifications. Also, check belt routing to make sure there is no interference between the belts and other engine components. Spark Plugs Spark plugs must fire properly to assure engine performance and emission control. New plugs should be installed at the mileage specified in the appropriate maintenance chart. The entire set should be replaced if there is any malfunction due to a faulty spark plug. Refer to the "Vehicle Emission Control Information" label in the engine compartment for spark plug information. Spark Plug Wires The spark plug wires should be kept clean and properly connected. Terminals should be fully seated. Cracked, damaged, or faulty wires should be replaced. Engine Air Cleaner Filter Under normal driving conditions, replace the air filter at the intervals shown on "Maintenance Schedule A." If, however, you drive the vehicle frequently under dusty or severe conditions, the filter element should be inspected periodically and replaced if necessary at the intervals shown on "Maintenance Schedule B." WARNING! The air induction system (air cleaner, hoses, etc) can provide a measure of protection in the case of engine backfire. Do not remove the air induction system (air cleaner, hoses, etc) unless such removal is necessary for repair or maintenance. Make sure that no one is near the engine compartment before starting the vehicle with the air induction system (air cleaner, hoses, etc) removed. Failure to do so can result in serious personal injury.