Toyota COMPUTER-CONTROLLED SYSTEM Training Manual page 104

T Basic ignition advance angle
ESA - Functions of Engine EC U
The basic ignition advance angle in the ESA
system corresponds to the vacuum advance and
governor advance angles in conventional EFI .
Data on the optimal basic ignition advance angle
(which correspond to the engine speed and
intake manifold pressure or intake air volume)
are held in the memory of the Engine ECU .
IDLE CONTACT CLOSED (ON )
The ignition timing is advanced in accordance
with the engine speed when the idle contact
closes .
om C
C ~
U C
- f0
>
CO
c o
m
Low
-
Engine speed
-RELEVANT SIGNALS
• Thro
tt
le position (IDL)
• Engine speed
(NE)
High
OHP 6 6
REFERENCE
In some engine models, the basic ignition ad-
vance angle changes (as shown by the dotted
line in the graph above) depending on whether
the air conditioner is on or off .
In addition, there are also models in which the
advance angle is "0" at the time of the stan-
dard idle speed .
\1 i
IDLE CONTACT OPEN (OFF )
The Engine ECU determines the basic ignition
advance angle based on data stored in its
memory, and based on the intake manifold
pressure (or the intake air volume) and engine
speed .
In some engine models, two types of basic
ignition advance angle data are stored in
memory . One or the other of these two sets of
data is then used, depending on the fuel octane
rating (premium or regular) .
The driver can select the data to be used by
setting the fuel control switch or connector to
match the octane rating of the gasoline used .
In vehicles equipped with the fuel octane
judgment capability, the relevant data are
accessed automatically in accordance with the
knock (KNK) signal from the knock sensor (Se e
page 116) .
RELEVANT SIGNALS
• Intake manifold pressure (PIM) or intake air
volume (VS, KS or VG )
• Engine speed (NE )
• Throttle position (IDL )
• Fuel control switch or connector (R-P )
• Engine knocking (KNK)
J
92