Grand Cherokee 2WD L6-242 4.0L VIN S MFI (1993)
-
Throttle Position Sensor (TPS)
Based On These Inputs The PCM Will:
-
Adjust engine idle speed through the IAC motor.
-
Adjust ignition timing.
-
Operate A/C Compressor Clutch relay (if selected).
-
Ignore oxygen sensor input. The PCM will enter fuel cut-off strategy (under hard deceleration).
-
Determine proper injector pulse width and continue injection (under normal deceleration).
Engine Start-Up
THIS IS AN OPEN LOOP MODE.
When the starter motor is engaged, the Powertrain Control Module (PCM) receives input from:
-
Battery voltage
-
Crankshaft position (CKP) sensor
-
Engine coolant temperature (ECT) sensor
-
Intake air temperature (IAT) sensor
-
Throttle position sensor (TPS)
-
Camshaft position (CMP) sensor
-
Starter relay
Based on these inputs the PCM will:
-
Monitor crankshaft and camshaft position sensor. If signals are not received within 1 second, the PCM will shut down the Automatic Shutdown
(ASD) and fuel pump relays.
-
Supply the injectors with a ground path, firing all injectors until the PCM determines crankshaft position.
-
Fire injectors in sequence, once PCM has determined crankshaft position.
-
Compare RPM Manifold Absolute Pressure (MAP) sensor reading to idle speed MAP sensor reading. If the PCM does not detect a minimum
difference it will set a Diagnostic Trouble Code.
-
Determine proper ignition timing.
Engine Warm-Up
THIS IS AN OPEN LOOP MODE.
During engine warm-up, the Powertrain Control Module (PCM) receives input from:
-
Battery voltage
-
Crankshaft position (CKP) sensor
-
Engine coolant temperature (ECT) sensor
-
Intake air temperature (IAT) sensor
-
Manifold absolute pressure (MAP) sensor
-
Throttle position sensor (TPS)
-
Camshaft position (CMP) sensor
-
A/C select switch (if equipped)
Based on these inputs the PCM will:
