®
POWER ENRICHMENT
EFI - Functions of Engine EC
U
When the engine is operating under a heavy
load, the injection volume is increased in
accordance with the load in order to ensure
proper engine operation
.
Methods for sensing whether the engine is
operating under a heavy load differ depending
on the engine model
. In some engines, it is
determined by the throttle valve opening angle,
while in other engines, it is determined by the
intake air volume
. This enrichment increases the
injection volume by 10 to
30%
.
-RELEVANT SIGNAL
S
• Throttle position (PSW or VTA
)
• Intake manifold pressure
(
PIM) or intake air
volume
(VS, KS or VG
)
• Engine speed (NE
)
(_
REFERENC
E
1
. In some engine models, the amount of
increase also differs in accordance with
the coolant temperature
.
2
. In some engine models, when the coolant
temperature is high, the fuel injection
amount is increased to lower the exhaust
gas temperature and to prevent the
engine from overheating
.
3
. In some engine models, the kick-down
switch (KD) signal is used as a condition
for begining this correction
.
AIR-FUEL RATIO
CORRECTION DURING
TRANSITION
S
A
"transition"
is the moment when the engine
rpm changes, either during acceleration or
deceleration
. During a transition, the injection
volume must be increased or decreased to
assure proper engine pe
rf
ormance
.
a
. Acceleration Enrichment Correctio
n
When the Engine ECU detects engine
acceleration based on signals from the
various sensors, it increases the injection
volume to improve acceleration
performance
.
The initial correction value is determined by
the coolant temperature and the rate of
acceleration
. The amount gradually
decreases from that point
.
b
. Deceleration Lean Correctio
n
When the ECU detects engine deceleration,
it decreases the injection volume as
necessary to prevent over-rich injection
during deceleration
.
-RELEVANT SIGNAL
S
• Intake manifold pressure
(
PIM) or intake air
volume (VS, KS or VG
)
• Engine speed (NE
)
• Vehicle speed (SPD
)
• Throttle
position
(IDL, PSW or VTA)
• Coolant temperature (THW
)
74
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