sensor CHEVROLET CAMARO 1982 Repair Guide

GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 711
THROTTLE BODY INJECTION SYSTEM

SYSTEM DESCRIPTION
The throttle body injection (TBI) system used on 2.5L (VIN 2) and 5.0L (VIN E)
engines is centrally located
on the intake manifold. Its function is to supply the
correct air/fuel mixture to the engine, as directed by the Engine Control Module
(ECM).
The TBI unit consists of two relatively simple casting assemblies: a throttle body
and a fuel metering assembly. Components include, a pressure regulator, idle
air control valve, fuel injector(s), thro ttle position sensor, fuel inlet and a fuel
return fitting.
The Throttle Body Injection identifi cation number is stamped on the lower
mounting flange located near the TPS. Th e number is in alphabetical code and
should be noted before servicing the unit.
An oxygen sensor in the exhaust syst em functions to provide feedback
information to the ECM as to oxygen content in the exhaust. The ECM then
uses this information to modify fuel de livery to achieve as near as possible an
ideal air/fuel ratio of 14.7 :1. This ratio permits the ca talytic converter to become
more effective in reducing emissions wh ile providing acceptable driveability.
Should you encounter any type of engine performance problem, have a
complete CCC system test performed by a qualified, professional technician. If
the fault lies in the injection system, you can use the following procedures to
remove the TBI unit and replace the defective component(s).
RELIEVING FUEL SYSTEM PRESSURE
1. Disconnect the negative battery cable to prevent fuel discharge if the key
is accidentally turned to the RUN position.
2. Loosen the fuel filler cap to relieve fuel tank pressure and do not tighten
until service has been completed.
3. Fuel system pressure is automatic ally relieved when the engine is turned
OFF. No further action is necessary.
When disconnecting fuel lines, there ma y still be a small amount of fuel
released. Cover the fuel line connection wi th a shop cloth to collect the fuel,
then place the cloth in an approved container.
ELECTRIC FUEL PUMP
REMOVAL & INSTALLATION
The fuel pump is part of t he fuel sender assembly located inside the fuel tank.
1. Release the fuel syst em pressure and disconnec t the negative battery
cable.

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4. Start the car and observe the fuel
pressure reading. It should be 9-13 psi
(62-90 kPa).
5. Relieve the fuel pressure.
6. Remove the fuel pressure gauge.
7. Reinstall the fuel line.
8. Start the car and che ck for fuel leaks.
9. Remove plug covering THERMAC va cuum port on the TBI and install the
air cleaner.
THROTTLE BODY
REMOVAL & INSTALLATION 1. Relieve the fuel system pressure.
2. Disconnect the THERMAC hose from the engine fitting and remove the
air cleaner.
3. Detach the electrical connectors at the idle air control, throttle position
sensor, and the injector.
4. Disconnect the throttle linkage, re turn spring, and cruise control (if
equipped).
5. Disconnect the throttle body vacuum hoses, fuel supply and fuel return
lines.
6. Disconnect the 3 bolts securing the throttle body and remove the throttle
body.
7. To install, reverse the removal procedures. Replace the manifold gasket
and O-rings.
8. Perform the minimum idle speed adjustment, if necessary.

Fig. 1: Single injector TBI unit

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8. The idle speed should be 450-500 rpm, adjust as necessary.
WARNING - Correct minimum idle speed adj ustment is critical to vehicle
performance and component durability. Incorrect minimum idle speed
adjustment (too high) will caus e the IAC valve pintle to constantly bottom in it's
seat and result in early valve failure. If minimum idle speed is adjusted too low,
the vehicle may not start in cold weather or may stall during warm-up.
Turn the ignition OFF and reconnect the IAC motor connector.
9. Reconnect the distributor set-timing connector.
10. Use silicone sealant to co ver the throttle stop screw.
THROTTLE POSITION SENSOR (TPS)
1982-1983 2.5L TBI engines ar e equipped with an adjustable throttle position
sensor. This procedure should only be performed after replacing the TPS or
diagnosis leads to incorrect TPS adjustment.
1. Remove the throttle position sensor connector and install three jumper wires between the connector and the s ensor. Connect a digital voltmeter
to terminals B and C.
2. Turn the ignition ON. It should display bet ween 0.45-0.60 volts.
3. Adjust the TPS, if necessary, by loosening the attaching screws and
rotating the TPS.
4. Tighten the screws, remove the jumper wires with the ignition OFF and
reconnect the harness connector.
5. Start the engine and check fo r proper idle operation.

Fig. 7: TPS adjustment

GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 723

Fig. 2: Fuel pressure regulator assembly
THROTTLE POSITION SENSOR (TPS)
REMOVAL & INSTALLATION 1. Remove the air cleaner.
2. Disconnect the electrical connector.
3. Remove the TPS attaching screws and lockwashers.
4. Remove the TPS.
To install: 5. Install the throttle position sensor. On 2.5L engines, make sure the TPS pickup lever is located above the tang on the throttle actuator lever. On
5.0L engines, line up the TPS lever with the TPS drive lever on the
throttle body.
6. Install the TPS attaching screws.
7. Adjust the TPS volt age, if applicable.
8. Reconnect the electrical connector.
9. Install the air cleaner.
IDLE AIR CONTROL (IAC) VALVE
REMOVAL & INSTALLATION 1. Unplug the electrical connector from idle air control valve.
2. Remove the idle air control valve.
To install: 3. Before installing the idle air contro l valve, measure the distance that the
valve is extended. Measurement s hould be made from the motor housing
to the end of the cone. It should not exceed 28.5mm (1
1/8 in.), or damage
to the valve may occur when installed.
4. Identify the replacement IAC valve as being either Type 1 (with collar at
electric terminal end) or Type 2 (without collar). If measuring distance is
greater than specified abov e, proceed as follows:
• Type 1: Use finger pressure to slowly retract the pintle.

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To install:
9. Replacement of the manifold cover or either throttle body requires throttle
valve synchronizing and checking of the throttle rod alignment (see
"Preliminary Adjustments"). Before installing the replacement throttle
body unit(s) on the engine, perform the following steps:
a. If the tamper resistant plugs co vering the throttle stop screws are
in place, remove the plugs.
b. If the front TBI unit throttle syn chronizing screw has a welded
retaining collar, grind off the weld.
c. Block possible movement of the throttle lever, relieving the force
of the heavy spring against the throttle synchronizing screw. This
prevents the levers from coming into contact.
If the lever is not blocked before the thro ttle synchronizing screw is removed,
the screw may be damaged, and reinstallation will be accomplished only with
great difficulty.
d. Remove the synchronizing screw and collar. Discard the collar and reinstall the screw. The blocking from the throttle lever (installed in the
previous step) can now be removed.
CAUTION - The collar must be removed to prevent possible interference with
the air cleaner. Failure to do so c ould result in personal injury
10. Use new gaskets and tighten the TB I bolts to 120-168 inch lbs. (13-19
Nm) during installation.
11. Perform the preliminary adjustm ents. These procedures must be
followed before further assembly.
12. Reconnect the fuel lines to the TBI units. Use a backup wrench to
prevent the nuts from tu rning in the TBI unit.
13. Reconnect the throttle cable and detent cable.
14. Reconnect all related vacuum lines.
15. Reconnect the electrical connectors.
16. With the engine OFF, depress the accelerator pedal to the floor and
release. Check for free return of the pedal.
17. Check the throttle position sensor voltage and adjust if necessary.
18. Perform the Minimum Idle and Thro ttle Valve Synchronization adjustment
procedures.
Rear Unit 1. Relieve the fuel system pressure.
2. Remove the air cleaner assembly, noting the connection points of the
vacuum lines.
3. Disconnect the electrical connectors at the injector, idle air control motor,
and throttle position sensor.
4. Disconnect the vacuum lines from the TBI unit, noting the connection
points. During installation, refer to the underhood emission control
information decal for vacuum line routing information.

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17. Check the throttle position sensor voltage and adjust if necessary.
18. Perform the Minimum Idle and Thro
ttle Valve Synchronization adjustment
procedures.
INJECTOR REPLACEMENT
The removal and installation procedures fo r the Crossfire injection system's fuel
injector is identical to the Throttle Bo dy Injection (TBI) system. Please refer to
the TBI fuel injector procedures earlier in this repair guide.
ADJUSTMENTS
PRELIMINARY ADJUSTMENTS
The preliminary adjustments are performed if tampering with the idle speed or
synchronization is evident and when either of the throttle bodies or the manifold
cover have been replaced. They must be performed BEFORE the Minimum Idle
and Throttle Valve Synchronizing procedure.
THROTTLE VALVE SYNCHRONIZING
1. Turn BOTH front and rear unit throttle stop screws counterclockwise enough to break contact with the related throttle lever tangs.
2. Adjust the throttle synchronizing scr ew to allow BOTH throttle valves to
close. The throttle rod end bearing w ill move freely on the front unit
throttle lever stud when both valves are closed.
3. Turn the front unit th rottle stop screw clockwise slowly until it makes
contact with the throttle lever tang. Turn the screw clockwise an
additional
1/4 turn.
4. Turn the rear unit throttle stop screw clockwise slowly until it makes
contact with the throttle lever t ang. Turn the screw an additional
1/2 turn.

Fig. 1: Blocking the throttle levers

GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 732
MINIMUM IDLE AND THROTTL
E VALVE SYNCHRONIZING
The throttle position of each throttle body must be balanced so that the throttle
plates are synchronized and open si multaneously. These adjustment
procedures must be followed AFTER performing the "Preliminary Adjustments".
1. Remove the air cleaner and plug the vacuum port on the rear TBI unit for
the thermostatic air cleaner.
2. Remove the tamper resistant pl ugs covering both unit throttle stop
screws, if necessary.
3. Block the drive wheels and apply the parking brake.
4. Connect a tachometer to measure rpm.
5. Start the engine and allo w the engine rpm to stabilize at normal operating
temperature.
6. Have a helper apply the brakes and place the transmission in DRIVE.
7. Plug the idle air pass ages of each throttle body with plugs (J-33047 or
equivalent). Make sure the plugs are seated fully in the passage so that
no air leaks exist. The engine rpm should decrease below curb idle
speed. If the engine rpm does not decreas e, check for a vacuum leak.
8. Remove the cap from the ported tube on the rear TBI unit and connect a
vacuum gauge or water manometer.
9. Adjust the rear unit throttle stop screw to obtain approximately
1/2 in. Hg
as read on the vacuum gauge, or 6 in. H
2O as read on the manometer. If
not able to adjust to this level, check that the front unit throttle stop is not
limiting throttle travel.
10. Remove the vacuum gauge or manometer from t he rear unit and install
the cap on the port ed vacuum tube.
11. Remove the cap from the ported va cuum tube on the front TBI unit and
install the gauge or manomet er as before. If the reading is not the same
as the rear unit, proceed as follows: a. Locate the throttle synchronizing screw and collar on the front TBI
unit. The screw may be welded to discourage tampering with this
adjustment. Break the weld, if ne cessary, and install a new screw
with a thread seali ng compound applied.
b. Adjust the screw to obtain approximately
1/2 in. Hg as read on the
vacuum gauge, or 6 in. H
2O on the manometer.
12. Remove the gauge or manometer fr om the ported tube and reinstall the
cap.
13. Adjust the rear throttle stop screw to obtain 475 rpm, with the
transmission in D and the parking brake applied. On manual
transmission models, leave the gear selector in N.
14. Turn the ignition OFF and pl ace automatic transmission in N.
15. Remove idle air passage plugs.
16. Start the engine. It may run at a high rpm but the engine speed should
decrease when the idle air control va lves close the air passages. Stop
the engine when the rpm decreases.
17. The throttle position sensor (TPS) voltage should be checked and adjusted, if necessary.
18. Connect the vacuum line to the TBI unit and install the air cleaner.
19. Reset the idle speed control motors by driving the vehicle to 45 mph.

GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 733
THROTTLE POSITION SENSOR (TPS)
An accurate digital voltmeter is
needed to perform this adjustment.
1. Remove the air cleaner.
2. Disconnect the TPS electrical connector.
3. Install three jumper wires betwe en the TPS and the TPS wiring terminal
connections.
4. Turn the ignition ON, engine stopped, measure the voltage between
terminals B and C.
5. The display should read between 0.45-0.60 volts.
6. Loosen the screws and rotate the TPS to obtain the correct voltage, if necessary.
7. Tighten the TPS screws and turn the i gnition OFF. Remove the jumpers.
8. Reconnect the wir ing to the TPS.
9. Install the air cleaner.

Fig. 5: TPS adjustment
FUEL PRESSURE REGULATOR
REMOVAL & INSTALLATION
The removal and installation procedures fo r the Crossfire injection system's fuel
pressure regulator is identical to t he Throttle Body Injection (TBI) system.
Please refer to the TBI fuel pressure r egulator procedures earlier in this repair
guide.
THROTTLE POSITION SENSOR (TPS)
REMOVAL & INSTALLATION
1. Remove the air cleaner.
2. Disconnect the electrical connector.
3. Remove the TPS attaching screws and lockwashers.
4. Remove the TPS.
To install:

GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 734
5. Install the throttle position sensor
. Make sure the TPS pickup lever is
located above the tang on the throttle actuator lever.
6. Install the TPS attaching screws.
7. Adjust the TPS voltage.
8. Reconnect the electrical connector.
9. Install the air cleaner.
IDLE AIR CONTROL VALVE
REMOVAL & INSTALLATION 1. Remove the air cleaner.
2. Detach the electrical connection fr om the idle air control assembly.
3. Using a 1
1/4 in. wrench, remove the IAC valve from the throttle body. On
IAC valves secured with screws, remove the attaching screws.
Before installing a NEW IAC valve, measur e the distance that the conical valve
is extended. Measurement should be made from the motor housing to the end
of the cone. Distance s hould be no greater than 1
1/4 in. (32mm). If the cone is
extended too far, damage may result when the motor is installed. If necessary,
push on the end of cone until it is retracted the correct distance.
4. Installation is the reverse of remo val. Torque threaded valves to 13 ft.
lbs. (17 Nm).

Fig. 1: IAC valve pintle measurement

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Fig. 2: IAC valve installation
MULTI-PORT FUEL INJECTION SYSTEMS

SYSTEM DESCRIPTIONS
The Multi-Port Fuel Injection (MPFI or MFI) systems were first introduced on the
1985 models. They may be called different names (Port Fuel Injection-PFI,
Tuned Port Injection-TPI, Sequential Fuel Injection-SFI), however, all of the
systems are similar in operation.
The systems are controlled by an Elec tronic Control Module (ECM) which
monitors the engine operations and gen erates output signals to provide the
correct air/fuel mixture, ignition timing and idle speed. Input information to the
ECM is provided by the oxygen sens or, temperature sensors, detonation
sensor, mass air flow sensor and throttle position sensor. A system may use all
or some of these sensors, depending on the year and engine application. The
ECM also receives information concerning engine rpm, road speed,
transmission gear position, power steer ing and air conditioning status.
All of the systems use multiple injector s, aimed at the intake valve at each
intake port, rather than the centrally lo cated injector(s) found on the earlier
Throttle Body Injection (TBI) and Crossfir e Injection systems. The injectors are
mounted on a fuel rail and ar e activated by a signal from the electronic control
module. The injector is a solenoi d-operated valve which remains open
depending on the width of t he electronic pulses (length of the signal) from the
ECM; the longer the open time, the more f uel is injected. In this manner, the
air/fuel mixture can be precisely c ontrolled for maximum performance with
minimum emissions.
There are two different types of f uel management systems used on the multi-
port fuel injection engines. The mass air flow system and the speed density
system.