Ford Tempo/Topaz 1984-1994 Repair Guide

Description & Operation


See Figures 1, 2 and 3

The gasoline engine equipped Tempo /Topaz utilizes Ford's Thick Film Ignition (TFI-IV) System. This ignition system features an extended reach 2mm tapered seat spark plug, a multi-point rotor, a universal distributor (which eliminates the conventional centrifugal and vacuum advance mechanisms) and provisions for fixed octane adjustment. The TFI-IV system module has 6 pins and uses an E-Core ignition coil, named after the shape of the laminations making up the core. This type ignition system was used in the Tempo/Topaz from 1984 through 1992.

There are 2 types of TFI-IV ignition systems:

PUSH START: This TFI-IV system first appeared on the 1984 Tempo/Topaz and was used on the 2.3L High Swirl Combustion (HSC) engine. It featured a "push start'' mode which allowed manual transmission vehicles to be push started. Automatic transmission vehicles must not be push started because they were not equipped with this.
COMPUTER CONTROLLED DWELL: This second TFI-IV system appeared on the 1990 model and features an EEC-IV controlled ignition coil charge time.

All TFI-IV ignition systems have a distributor base-mounted TFI ignition module and a hall effect stator assembly. The distributor also contains a provision to change the basic distributor calibration with the use of a replaceable octane rod. The replacement of a rod allows for a retard rate of either the standard 0° to 3°or 6°. No other calibration changes are possible.

The operation of the distributor is accomplished through the Hall Effect stator assembly which causes the ignition coil to be switched off and on by the EEC-IV computer or TFI-IV modules. The vane switch within this assembly consists of a Hall sensor on one side and a permanent magnet on the other side.

A rotary armature, made of ferrous metal, is used to trigger the Hall Effect switch. When the window of the armature is between the magnet and the Hall Effect device, a magnetic flux field is completed from the magnet through the Hall Effect device back to the magnet. As the vane passes through the opening, the flux lines are shunted through the vane and back to the magnet. A voltage is produced while the vane passes through the opening. When the vane clears the opening, the window causes the signal to go to 0 volts. In the EEC-IV system, the signal is used for crankshaft position sensing and the computation of the desired spark advance based on the engine demand and calibration. The voltage distribution is accomplished through a conventional rotor, cap and ignition wires.

In this system, the TFI-IV module supplies voltage to the Profile Ignition Pick-up (PIP) sensor, which in turn sends the crankshaft position information to the TFI-IV module. The TFI-IV module then sends this information to the EEC-IV module, which determines the spark timing and sends an electronic signal to the TFI-IV ignition module to trigger the coil and produce a spark to fire the spark plug.

Starting with the 1993 Tempo/Topaz the TFI ignition system was updated. In reality, very little changed between the new and the old systems. The principles and components remained similar. The only real update was the departure of the TFI Module and the replacement with an ignition control module.

Click image to see an enlarged view

Fig. Fig. 1: Thick Film Ignition System (TFI-IV)

Click image to see an enlarged view

Fig. Fig. 2: TFI ignition system functional diagram-automatic transaxle

Click image to see an enlarged view

Fig. Fig. 3: TFI ignition System functional diagram-manual transaxle