Jeep Engines - Oljeep

2.5L POWER TECH IN-LINE 4 (IGNITION SYSTEM) 87Ignition SystemTHROTTLE BODY FUEL INJECTION (TBI)IGNITION SYSTEMThe 2.5L engine TBI ignition system is controlled by theElectronic Control Unit (ECU). The ignition systemconsists of0 Ignition Control Module (ICM)The solid-state Ignition Control Module (ICM)consists of a solid-state ignition circuit and anintegrated ignition coil that can be removed andserviced separately if necessary.Ignition advancehetard is controlled electronically bythe Electronic Control Unit (ECU). Electronic signalsfrom the ECU to the ICM determine the amount ofignition timing advance or retard needed to meetvarious engine load requirements.The ECU provides an input signal to the ICM. TheICM has only two outputs:- Tachometer signal to the tachometer anddiagnostic connector- High voltage from the coil to the distributor cap0 Electronic Control Unit (ECU)The ECU controls the fuel injector pulse width andignition timing based on inputs received from sensorsthat react to exhaust gas oxygen content, air-fueltemperature, coolant temperature, manifold absolutepressure, battery voltage, crankshaft position (enginespeed), throttle position and inputs from switches thatare triggered by power steering pump output pressure,wide open throttle conditions, and transmission gearselection (automatic transmissions only). Batteryvoltage is also monitored to determine injector pulsewidth. These sensors and switches are considered ECUinputs. For more information, refer to ‘Fuel Deliveryand Fuel Injection Systems’ section of this chapter.0 DistributorThe 2.5L engine distributor does not have built-incentrifugal or vacuum assisted advances. Ignitiontiming/advance is controlled by the Electronic ControlUnit (ECU). Because ignition timing is controlled bythe ECU, base ignition timing is not adjustable on anyof these engines. The distributor is locked in place byan ear on the distributor housing that a hold down boltpasses through when the distributor is installed.Because the distributor position is locked wheninstalled, its rotational position cannot be changed. DONOT attempt to modify the distributor housing to geltdistributor rotation.Distributor Cap and Rotor SetDistributor cap and rotor for 2.5L engines only.P4.529685 Distributor cap and rotor set.MULTI-POINT FUEL INJECTION (MPI) IGNITIONSYSTEMThe 2SL engine MPI ignition system is controlled by thePowertrain Control Module (PCM).The MPI ignition system consists ofSpark PlugsIgnition CoilSecondary Ignition CablesDistributor (contains rotor and camshaft position sensor)Powertrain Control Module (PCM)Crankshaft Position, Camshaft Position, ThrottlePosition and MAP SensorsCamshaft Position SensorThe camshaft position sensor is located in the distributor.The sensor contains a hall effect device called a sync signalgenerator to generate a fuel sync signal. This sync signalgenerator detects a rotating pulse ring (shutter) on thedistributor shaft. The pulse ring rotates 180 degrees throughthe sync signal generator. Its signal is used in conjunctionwith the crankshaft position sensor to differentiate betweenfuel injection and spark events. It is also used to synchronizethe fuel injectors with their respective cylinders.When the leading edge of the pulse ring (shutter) enters thesync signal generator, the interruption of magnetic fieldcauses the voltage to switch high resulting in a sync signalof approximately 5 volts.When the trailing edge of the pulse ring (shutter) leaves thesync signal generator, the change of the magnetic fieldcauses the sync signal voltage to switch low to 0 volts.l- - 1 1