Equus 3145 - Digital Ford Code Reader (1981 - 1995) - Manual (Page 34)

Retrieving Codes
ENGINE TIMING CHECK (EEC-IV SYSTEMS)
31 Chapter 4
5. Press and release the TEST/HOLD button to put the
Code Reader in test mode. The vehicle's computer will
perform a Key On Engine Running Self test.
■ A square icon (on the right-hand side of the screen)
displays and flashes each time the Code Reader
receives a code. The code is then shown on the Code
Reader's display.
6. Wait until all codes have been sent (the flashing square
icon no longer appears) and, without disconnecting or
turning the Code Reader off, proceed to step 7.
NOTE: Do not concern yourself with the KOER test results
or any fault codes received at this time. The purpose of
briefly performing the KOER test is to put the computer
into an "Ignition Timing Check mode". This mode allows
you to test the ability of the vehicle's computer to
electronically control/advance ignition timing. Once the
timing check confirms that ignition timing is functioning
correctly, you can properly perform the KOER Self Test.
7. The vehicle's computer is programmed to advance ignition
timing 20° (+/- 3°) above the vehicle's “base timing” value,
and to freeze this setting for two minutes from the time
the last KOER code is received by the Code Reader. This
allows the user to check the computer's ability to advance
ignition timing.
■ Within this two-minute period, (remember, timing
degrees will remain fixed for only two minutes after
the last KOER code is received by the Code Reader),
check the ignition timing with a timing light and
ensure that it is 20° above the specified base timing
value (+/- 3° ).
Example: If base timing specification is 10° BTDC,
the acceptable timing light reading should be in the
range of 27° to 33° BTDC.
NOTE: Base timing specifications can be found on the
Vehicle Emission Control Information (VECI) decal. The
decal is located under the hood or near the radiator. If the
VECI decal is missing or damaged, refer to your vehicle's
service manual for specifications.
8. If timing light readings are not within the acceptable range,
base timing may be out of adjustment, or the computer may
have problems with the timing advance circuit.
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