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ing, detonation and cooling system malfunctions also SPARK PLUG SERVICE When replacing the spark plug and coil cables, route the cables correctly and secure them in the ap- SPARK PLUG REMOVAL Always remove the spark plug cable by grasping at the spark plug boot turning, the boot 1/2 turn and (1) Prior to removing the spark plug spray com- pressed air around the spark plug hole and the area (2) Remove the spark plug using a quality socket with a rubber or foam insert. (3) Inspect the spark plug condition. Refer to Spark Plug Condition in this section. SPARK PLUG GAP ADJUSTMENT Check the spark plug gap with a gap gauge. If the gap is not correct, adjust it by bending the ground SPARK PLUG INSTALLATION (1) To avoid cross threading, start the spark plug into the cylinder head by hand. (2) Tighten spark plugs to 28 N Im (20 ft. lbs.) torque. (3) Install spark plug cables over spark plugs. POWERTRAIN CONTROL MODULE (PCM) The ignition system is regulated by the powertrain control module (PCM) (Fig. 14). The PCM supplies ground path for the coil on and off, the PCM adjusts During the crank-start period the PCM advances ignition timing a set amount. During engine opera- • engine RPM • available manifold vacuum The PCM also regulates the fuel injection system. Refer to the Fuel Injection sections of Group 14. DISTRIBUTOR PICK-UP—PCM INPUT The engine speed input is supplied to the power- train control module (PCM) by the distributor pick- A shutter (sometimes referred to as an interrupter) is attached to the distributor shaft. The shutter con- Fig. 14 Powertrain control module (PCM) Fig. 15 Distributor—2.2L and 2.5L TBI Engines Fig. 13 Spark Plug Overheating 8D - 6 IGNITION SYSTEMS Ä |