Engine Start-Up Mode; Engine Warm-Up Mode - Jeep 1987 Wrangler Workshop Manual

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THROTTLE BODY FUEL INJECTION SYSTEM
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1 GENERAL INFORMATION
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SEE
1.8.
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• T h e fuel pump is activated by the E C U via the
relay.
T h e fuel pump will operate for approximately
one s e c o n d unless the engine is operating or the
starter motor is engaged.
T h e following engine s e n s o r s are activated and
begin providing input to the E C U :
• coolant temperature sensor ( C T S )
• manifold air/fuel temperature sensor
• manifold absolute pressure (MAP) s e n s o r
T h e up-shift indicator lamp is illuminated.
Engine Start-Up Mode
T h e following actions occur when the starter
motor is engaged.
T h e following inputs are received by the E C U :
• • coolant temperature s e n s o r ( C T S )
• starter motor relay
• s p e e d s e n s o r
• W O T switch
T h e fuel pump ballast resistor (if equipped) is
b y p a s s e d .
T h e fuel pump is activated by the E C U .
Voltage is applied to the injector and the E C U
controls the length of injection time.
T h e E C U determines the proper ignition timing
according to the input from the s p e e d sensor.
N O T E : If the W O T switch is engaged, the E C U
will deactivate the injector b e c a u s e a possible
flooding condition could exist.
Engine Warm-Up Mode
T h e following inputs are received by the E C U :
• coolant temperature
• manifold air/fuel temperature
• manifold absolute pressure
• engine s p e e d
• throttle position
• gear position (automatic transmission)
• A / C control positions
• engine detonation (knock)
T h e E C U provides a ground for the injector to
precisely control the opening and closing time
(pulse width) to deliver fuel to the engine.
T h e E C U controls engine idle s p e e d and the
throttle stop angle.
T h e E C U controls the ignition timing.
F o r v e h i c l e s e q u i p p e d w i t h a m a n u a l
t r a n s m i s s i o n , the up-shift indicator lamp is
controlled by the E C U according to engine
s p e e d and load.
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