Ford Probe 1989-1992 Repair Guide

Description and Operation



The electronic ignition on the 2.2L normally aspirated engine is a fully transistorized, high energy system. It is a conventional electronic ignition system in that it operates independent of the Electronic Control Assembly (ECA) for the most part, with both centrifugal and vacuum advance mechanisms controlling ignition advance. The ignition timing is advanced by vacuum at low speeds and by the centrifugal mechanism at higher speeds. The ECA does modify timing at altitudes above 6500 ft. to maintain proper engine performance and satisfactory exhaust emissions.

The electronic ignition on the 2.2L turbocharged engine is entirely electronic and is controlled by the ECA. The ECA sends the spark timing signal through the ignition module to the distributor based on its triggering signal from the following switches and sensors:

Vane air flow meter
Idle switch
Neutral gear switch
Clutch engage switch
EGR valve position sensor
Knock sensor
Throttle position sensor
Engine coolant temperature sensor
Engine coolant temperature switch

Other non-electronic components in the system include the starter interlock switch, battery, distributor, spark plugs, high tension leads and ignition module. The distributor provides a signal to the ECA to indicate crankshaft top dead center by means of its cylinder TDC sensors.

Both systems operate in the same manner. When the ignition switch is turned ON , the power relay closes and changes the coil primary windings. When the engine is running, the ignition module grounds the negative side of the coil primary circuit which induces spark. This results in an inductive charge built up in the secondary circuit. The spark is then sent to the distributor where the rotor and distributor cap delivers it to each spark plug.

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Fig. Fig.1Ignition system components 2.2L engines


The 3.0L engine is equipped with the Thick Film Integrated TFI-IV electronic ignition system. In this system, the distributor is driven off the camshaft and uses no centrifugal or vacuum advance. The distributor contains the TFI ignition module and a hall effect stator assembly.

The TFI-IV module supplies voltage to the Profile Ignition Pickup (PIP) sensor, which sends the crankshaft position information to the TFI-IV module. The TFI-IV module then sends this information to the ECA, which determines the spark timing and sends and electronic signal to the TFI-IV ignition module to turn off the coil and produce the spark to fire the plug.

The operation of the distributor is accomplished through the Hall Effect stator assembly, causing the ignition coil to be switched off and on by the ECA and TFI-IV module. The vane switch is an encapsulated package consisting of a Hall sensor on one side and a permanent magnet on the other side. A rotary vane cup, made of ferrous metal, is used to trigger the signal off and on. When the window of the vane cup is between the magnet and the Hall effect device, a magnetic flux field is completed from the magnet through the Hall effect device and back to the magnet. As the vane passes through this opening, the flux lines are shunted through the vane and back to the magnet. During this time, a voltage is produced as the vane passes through the opening. When the vane clears the opening, the window edge causes the signal to go to zero volts. The signal is then used by the ECA for crankshaft position sensing and the computation of the desired spark advance based on engine demand and calibration. The voltage distribution is accomplished through a conventional rotor, cap and ignition wires.

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Fig. Fig. 2 TFI-IV electronic ignition system 30L engine