Equus 3145 - Digital Ford Code Reader (1981 - 1995) - Manual (Page 43)

Retrieving Codes
ADDITIONAL TESTS FOR EEC-IV SYSTEMS
Chapter 4 40
■ The vehicle’s computer sends a voltage output signal
or a ground signal to energize the actuators. If an
actuator is not responding to the Output State Check,
follow the procedures described in the vehicle's service
manual to check computer actuator output circuit
voltages and/or grounds.
6. After performing the Output State Check, turn off the
ignition and disconnect the Code Reader from the test
connectors.
Cylinder Balance Test
(Vehicles equipped with Sequential Electronic Fuel
Injected (SEFI) systems only)
The Cylinder Balance Test assists in finding a weak or non-
contributing cylinder. The computer shuts off fuel (cuts off
power to injectors) to each cylinder, in sequence, and monitors
for RPM changes (drop). Based on this information, the
computer determines if all the cylinders are contributing power
equally (for proper engine operation), or if some cylinders are
only contributing partially or not contributing at all.
SEFI Introduction
Sequential Electronic Fuel Injection (SEFI) belongs to a family
of fuel injection systems called "Multiport/Multipoint Fuel
Injection".
Multiport (MFI) fuel injection systems contain one fuel injector
per cylinder, and the vehicle's computer electronically controls
their operation. On some multiport fuel injection system, the
injectors all fire at the same time and at every engine
revolution. On other systems the injectors fire in groups and/or
at every other engine revolution.
What distinguishes Sequential Electronic Fuel Injection
systems from other multiport fuel injection systems is that
each injector is independently energized and fires sequentially
one after the other in the proper firing order. This gives the
vehicle computer more control to cut the fuel to one injector at
a time (this can't be accomplished on the other systems
because they fire in groups of two or more injectors).
The computer can be put in "Cylinder Balance Test Mode" by
performing the KOER Self Test, waiting until all the KOER
codes have been transmitted to the Code Reader, and then
lightly taping the accelerator (follow the Cylinder Balance Test
procedures, following).
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