Toyota COMPUTER-CONTROLLED SYSTEM Training Manual page 109

ESA - Functions of Engine EC U
OTHER CORRECTION S
Engines have been developed with the following
corrections added to the ESA system (in addition
to the various corrections explained so far), in
order to adjust the ignition timing with
extremely fine precision .
a . Transition Correctio n
During the transition (change) from deceleration
to acceleration, the ignition timing is either
advanced or retarded temporarily in accordance
with the acceleration .
b . Cruise Control Correctio n
When driving downhill under cruise control, in
order to provide smooth cruise control operation
and minimize changes in engine torque caused
by fuel cut-off due to engine braking, a signal is
sent from the Cruise Control ECU to the Engine
ECU to retard the ignition timing .
c . Traction Control Correctio n
This retards the ignition timing, thus lowering
the torque output by the engine, when the
coolant temperature is above a predetermined
temperature and the traction control system is
operating .
d . ACIS (Acoustic Control Induction System)
Correctio n
When the engine speed rises above a
predetermined level, the ACIS operates . At that
time, the Engine ECU advances the ignition
timing simultaneously, thus improving output .
See page 120 for details on the ACIS .
e . Intercooler Failure Correctio n
This correction retards the ignition timing if the
intercooler fail signal goes on .
MAXIMUM AND MINIMUM ADVANCE ANGLE
CONTRO L
If the ignition timing (initial ignition timing +
basic ignition advance angle + corrective ignition
advance angle) becomes abnormal, engine
operation will be adversely affected .
To prevent this, the Engine ECU controls the
actual ignition angle (ignition timing) so that the
sum of the basic ignition advance angle and
corrective ignition advance angle cannot be
greater or less than certain values .
These values are :
MAX . ADVANCE ANGLE
350 -450
MIN . ADVANCE ANGLE -10° - 0 °
Advance angle = Basic ignition advance angl e
+ corrective ignition advance
angle
97