Pontiac Fiero 1988 Service Manual page 532

D R I V E A B I L I T Y A N D E M I S S I O N S - F U E L INJECTION (TBI) 6E2-C2-1
SECTION C2
FUEL CONTROL SYSTEM - TBI MODEL 700
CONTENTS
o o o o ©
© © © © © I
. . « « <
O O O O i
GENERAL DESCRIPTION * .
PL)RPOSE • • • • • • • • • • • •
M O D E S O F O P E R A T I O N .
Starting M o d e . . . . . .
Clear Flood M o d e . • .
Run M o d e .
O p e n L o o p .
Closed L o o p
A c c e l e r a t i o n M o d e
D e c e l e r a t i o n M o d e
Battery V o l t a g e C o r r e c t i o n M o d e .
Fuel C u t o f f M o d e . .
FUEL CONTROL SYSTEM COMPONENTS
BASIC S Y S T E M O P E R A T I O N
T H R O T T L E B O D Y INJECTION (TBI) UNIT
Fuel Injector . .
Pressure R e g u l a t o r . . . . . . . .
e
. . «
Idle A i r C o n t r o l (IAC) V a l v e .
T h r o t t l e Position S e n s o r (TPS)
F U E L P U M P . .
F U E L P U M P E L E C T R I C A L CIRCUIT
DIAGNOSIS . . . .
F U E L C O N T R O L . . .
@ © e © ©
• • . » <
o o . «
a 9 & @ o
• o
» o •
C2-1 Idle A i r C o n t r o l (IAC) V a l v e C 2 - 5
C2-1 Driveability • * C 2 - 5
C2-1 ON-CAR SERVICE . C 2 - 6
C2-1 G E N E R A L S E R V I C E I N F O R M A T I O N . . . . . . C 2 - 6
C2-2 Fuel Pressure Relief P r o c e d u r e C 2 - 6
C 2 - 2 Fuel System Pressure Test C 2 - 6
C 2 - 2 C l e a n i n g a n d Inspection . . . . . . . C 2 - 6
C2-2 T h r e a d L o c k i n g C o m p o u n d • • • • C 2 - 6
C2-2 F U E L INJECTOR A S S E M B L Y . . . C 2 - 8
C 2 - 2 P R E S S U R E R E G U L A T O R A S S E M B L Y . . . . . . C 2 - 9
C 2 - 2 F U E L M E T E R A S S E M B L Y . . . . . . . . . . . . . . C 2 - 9
C2-2 T H R O T T L E P O S I T I O N S E N S O R (TPS) C 2 - 1 0
C 2 - 2 IDLE A I R C O N T R O L (IAC) V A L V E C 2 - 1 0
C2=3 T U B E M O D U L E A S S E M B L Y
. 0 . 0 . . . 0 0 . . .
C2-11
C2-3 T H R O T T L E B O D Y A S S E M B L Y
. . . . c . . .
C 2 - 1 2
C 2 - 3 M I N I M U M IDLE S P E E D C H E C K C 2 - 1 2
C 2 - 4 T H R O T T L E B O D Y INJECTION UNIT C 2 - 1 3
C2=4
F U E L H O S E / P I P E A S S E M B L I E S
. c . . .
C 2 - 1 3
C 2 - 4
M a t e r i a l s C 2 - 1 3
C2-5 Fuel Line Repair • • • • . < > • • • . C 2 - 1 4
C 2 - 5 F U E L P U M P / O I L PRESSURE S W I T C H C 2 - 1 4
C2-5 F U E L P U M P R E L A Y . C 2 - 1 4
C2-5 PARTS INFORMATION C 2 - 1 4
GENERAL DESCRIPTION
PURPOSE
The basic function of the fuel control system is to
control fuel delivery to the engine.
Fuel is delivered to the engine by a throttle body
injection (TBI) unit.
The main control sensor is the oxygen (O2) sensor,
which is located in the exhaust manifold. The O2
sensor tells the engine control module (ECM) how
much oxygen is in the exhaust gas, and the ECM
changes the air/fuel ratio to the engine by controlling
the fuel injector. A 14.7:1 air/fuel ratio is required for
efficient catalytic converter operation. Because of the
constant measuring and adjusting of the air/fuel ratio,
the fuel injection system is called a "Closed Loop"
System (Figure C2-1).
MODES OF OPERATION
The ECM looks at voltages from several sensors to
determine how much fuel to give the engine. The fuel
is delivered under one of several conditions, called
"modes". All the modes are controlled by the ECM.
[T]
ENGINE CONTROL MODULE (ECM)
[7] EXHAUST OXYGEN ( 0
2
) SENSOR
[7] THROTTLE BODY INJECTION UNIT (TBI)
CATALYTIC CONVERTER
8P 0352-SYE
4/3/87
Figure C2-1 - Closed Loop System
Starting Mode
When the key is first turned "ON," the ECM turns
on the fuel pump relay for two seconds, and the fuel
pump builds up pressure to the TBI unit. The ECM
checks the coolant temperature sensor, the throttle
position sensor (TPS), and manifold absolute pressure
(MAP) sensor, then determines the proper air/fuel