START INJECTION CONTROL
EFI - Functions of Engine EC
U
During engine starting, it is difficult for the
manifold pressure sensor (for D-type EFI) or the
air flow meter (for L-type EFI) to accurately
sense the manifold pressure or the amount of air
being taken in, due to large fluctuations in
engine speed
. For this reason, the Engine ECU
selects from its memory a basic injection
duration that is suitable for the coolant
temperature and engine speed, regardless of in-
take manifold pressure or intake air volume
. It
then adds to this an intake air temperature correc-
tion (See page 72) and a voltage correction (See
page 79) to obtain the actual injection duration
.
When the weather is cold, the cold start
injection system operates in order to improve
startability (See page
63)
.
Basic injection duration
during sta
rt
in
g
• THW
OHP 5
5
Injection signal during sta
rt
in
g
Low
---- On some models, injection
duration increases a
s
•N
E
Intake air temperature
correctio
n
•TH
A
Voltage correction
• +
B
20
(68
)
Coolant temperature °C (°F)
High
OHP 55
-RELEVANT SIGNALS
• Crankshaft angle (G)
• Engine speed (NE
)
• Coolant
temperature (THW)
• Intake air
temperature (THA)
• Battery voltage (+B
)
REFERENCE
In some engine models, the starter (STA)
signal is also used to inform the Engine ECU
that the engine is being cranked
.
70
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