Toyota COMPUTER-CONTROLLED SYSTEM Training Manual page 84

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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 )
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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 )
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