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IGNITION SWITCH ON (ZERO RPM) MODE When the multi-port fuel injection system is acti- vated by the ignition switch, the following actions oc- When the key is in the ON position and the engine is not running (zero rpm), the auto shutdown (ASD) ENGINE START-UP MODE This is an OPEN LOOP mode. The following ac- tions occur when the starter motor is engaged. If the PCM receives the camshaft position sensor and crankshaft position sensor signals, it energizes The PCM energizes all six injectors until it deter- mines crankshaft position from the camshaft position After determining crankshaft position, the PCM begins energizing the injectors in sequence. The PCM When the engine idles within 664 RPM of its tar- get RPM, the PCM compares current MAP sensor Once the ASD and fuel pump relays have been en- ergized, the PCM: ENGINE WARM-UP MODE This is a OPEN LOOP mode. The following inputs are received by the PCM: • manifold absolute pressure (MAP) • engine speed (crankshaft position sensor) • throttle position • A/C switch • battery voltage The PCM adjusts injector pulse width and controls injector synchronization by turning the individual The PCM adjusts ignition timing and engine idle speed. Engine idle speed is adjusted through the idle CRUISE OR IDLE MODE When the engine is at operating temperature this is a CLOSED LOOP mode. During cruising speed the • manifold absolute pressure • engine speed (crankshaft position sensor) • throttle position • exhaust gas oxygen content • A/C control positions • battery voltage The PCM adjusts injector pulse width and controls injector synchronization by turning the individual The PCM adjusts engine idle speed and ignition timing. The PCM adjusts the air/fuel ratio according ACCELERATION MODE This is a CLOSED LOOP mode. The PCM recog- nizes an abrupt increase in throttle position or MAP DECELERATION MODE This is a CLOSED LOOP mode. During decelera- tion the following inputs are received by the PCM: • manifold absolute pressure • engine speed • throttle position • exhaust gas oxygen content • A/C control positions • battery voltage The PCM may receive a closed throttle input from the throttle position sensor (TPS) when it senses an 2 sensor). During a closed throttle deceleration condition, the PCM grounds the exhaust gas recirculation (EGR) 14 - 154 FUEL SYSTEMS Ä |