Knocking Control for Turbo Engine OnlyEngine coolant tern.Advance mapperarure correctton
value- Barometric pressurecorrectton
DelonaIlon
sensorI
lgnmon codKnockmg correcllonprimary currenr
v
Knock wbral+onKnockmg LevelDelay anglelgnmon tlmtngdetemon- delermonmon - calculallon - derermmatlon
II
Y
FatlureIdeIeclton
6FUO565Engine knocking is detected and the ignition timing
is controlled accordingly to prevent continued
knocking and to protect the engine.
When knocking is detected, the engine control unit
delays the ignition timing according to the signal
from the detonation sensor until the knocking is
eliminated (up to a maximum 12” in crank angle). In
the case of an open or short circuit of the detonationsensor harness. the timing is delayed by a fixed
angle (approximately 8” in crank angle) to prevent
knocking.Energization Time Control
While
crankinaIf knocking continues, the advance angle map value
is corrected gradually in the delay direction.
In the absence of knocking, the map value is
corrected gradually in the advance direction. In this
way, optimum ignition timing is constantly control-
led; this control is effective even when fuels of
different octane ratings are used.
This means that the engine is protected from
knocking damage even when the fuel is switched
from premium to regular or vice versa.
Synchronizedwith crank angle
sensor signalcDuring normal operation
Map value
cor-Energizatlon time
responding to- is clipped at 75% of
battery voltageignition interval
IIn order to obtain stable ignition energy, the
ener-gization time of the ignition coil primary current is
controlled as to keep current at a constant value
when the primary current is shut off.
(1) DURING NORMAL OPERATION
Basic energization time
:The increase of the ignition coil primary current
changes with the battery voltage. Therefore, the
energization time is so controlled that the primary
current at time of ignition becomes
6A. The basic
energization time is so set that it is longer when the
battery voltage is low and is shorter when the
6FUO548Energization time clip:
The new two-coil ignition system has its ignition
interval doubled when compared to the convention-
al single
coil type, allowing a longer clip time. As a
result, a long energization time is secured for
sufficient ignition energy even during high speed
operation.
(2) WHILE CRANKING
When cranking, the ignition coil is energized in
synchronization with the crank angle signal.
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