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Once the auto shutdown and fuel pump relays have been energized, the PCM determines the fuel – engine coolant temperature – manifold absolute pressure – intake air temperature – engine revolutions – throttle position The PCM determines the spark advance based on the following: – engine coolant temperature – crankshaft position – camshaft position – intake air temperature – manifold absolute pressure – throttle position Engine Warm-Up Mode − This is an open loop mode. The PCM adjusts injector pulse width and Cruise or Idle Mode − When the engine is at normal operating temperature, this is a closed loop – throttle position – battery voltage – engine coolant temperature Acceleration Mode − This is a closed loop mode. The PCM recognizes an increase in throttle position Deceleration Mode − This is a closed loop mode. The PCM recognizes a decrease in throttle position Wide Open Throttle Mode − This is an open loop mode. The throttle position sensor notifies the 3.2.6 NON-MONITORED CIRCUITS The PCM does not monitor the following circuits, systems, and conditions even though they could may cause a DTC to be displayed for other systems. Engine Timing − The PCM cannot detect an incorrectly indexed timing chain, camshaft sprocket, or crankshaft sprocket. The PCM also Fuel Pressure − Fuel pressure is controlled by the fuel pressure regulator. The PCM cannot detect Fuel Injectors − The PCM cannot detect if a fuel injector is clogged, the pintle is sticking, or the Fuel Requirements − Poor quality gasoline can cause problems such as hard starting, stalling, and PCM Grounds − The PCM cannot detect a poor system ground. However, a diagnostic trouble code Throttle Body Air Flow − The PCM cannot detect a clogged or restricted air cleaner inlet or Exhaust System − The PCM cannot detect a plugged, restricted, or leaking exhaust system.(*) Cylinder Compression − The PCM cannot de- tect uneven, low, or high engine cylinder compres- Excessive Oil Consumption − Although the PCM monitors the exhaust stream oxygen content (*)NOTE: Any of these conditions could result in a rich or lean condition causing an oxygen sensor 3.2.7 SKIS OVERVIEW The Sentry Key Immobilizer System (SKIS) is an immobilizer system design to prevent unauthorized 5 GENERAL INFORMATION |