ignition CHEVROLET CAMARO 1982 Repair Guide

GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 735

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.

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The mass air flow systems measure the
mass of air that is drawn into the
engine cylinders, rather than just the vo lume. The sensor contains a hot-wire
sensing unit, which is made up of an electronic balanced bridge network.
Whenever current is suppli ed to the sensor, the bridge is energized and the
sensing hot-wire is heated. As the air enter s the mass air flow sensor, it passes
over and cools the hot wire. When the hot wire is cooled, it's resistance changes
and additional current is needed to k eep the bridge network balanced. This
increase in current is sent to the computer as a voltage signal and is used to
calculate the mass of the incoming air. The ECM uses this information to\

determine the duration of fuel injection pulse, ignition timing and EGR operation.
The speed density systems calculate the volume of air moving through the
intake. The ECM establishes the speed fact or through a signal from the ignition
module. The Manifold or Intake Air Temperature (MAT/IAT) and the Engine
Coolant Temperature (ECT) sensors work together to assure that proper
temperature information gets to the ECM wh ile the Manifold Absolute Pressure
(MAP) sensor monitors the changes in m anifold pressure which results from
changes in engine loading. These three se nsors contribute to the density factor.
Together, these inputs (engine speed, coolant temperature sensor, etc ...) are
the major determinants of the air/fuel mixture delivered by the fuel injection
system.
The following engines and fuel managem ent systems are covered in this
section:
• 1985-1989 2.8L MPFI - Mass Air Flow
• 1990-1992 3.1L MPFI - Speed Density
• 1985-1989 5.0L and 5.7L TPI - Mass Air Flow
• 1990-1992 5.0L and 5.7L TPI - Speed Density
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 reliev e the tank pressure and do not tighten
until service has been completed.
3. Connect J-34730-1 fuel pressure gauge or equivalent, to the fuel
pressure test valve. Wrap a shop towel around the fitting while
connecting the gauge to prevent spillage.
4. Place the end of the bleed hose into a suitable container and open the
valve to relieve the fuel system pressure.
ELECTRIC FUEL PUMP
REMOVAL & INSTALLATION
The fuel pump is part of t he fuel sender assembly located inside the fuel tank.

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14. Fill the fuel tank, tighten the f
uel filler cap and connect the negative
battery cable.
15. Turn the ignition switch to t he ON position for 2 seconds, OFF for 10
seconds, then back to the ON posit ion. Check for fuel leaks.

Fig. 2: Fuel pump assembly
TESTING 1. Relieve the fuel system pressure and check that there is an adequate
quantity of fuel in the tank.
2. Connect a fuel pressure gauge to the pressure connector fitting located
on the end of the fuel rail.

Fig. 3: Fuel pressure can be check ed using an inexpensive pressure/vacuum
gauge

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3. Make sure the ignition switch has
been in the OFF position for at least 10
seconds and that all accessories are OFF.
4. Turn the ignition switch ON and the pump will run for about 2 seconds.
Note the system pressure with t he pump running, it should be between
40-47 psi.
The ignition switch may have to be cycled to the ON position more than once to
obtain maximum pressure. It is also norma l for the pressure to drop slightly
when the pump first stops, but it should then hold steady.
5. If the pressure is not as specified, verify that fuel pump operation is
heard in the tank.
6. If fuel pump operation is not heard, inspect the fuel pump relay and
wiring.
7. If fuel pump operation is heard, inspect the filter and lines for restriction.
8. Start the engine and make sure the pr essure decreases about 3-10 psi at
idle.
9. If fuel pressure does not decrease, inspect the fuel pressure regulator
and hose.
10. Disconnect the fuel pressure gauge.
THROTTLE BODY
REMOVAL & INSTALLATION 1. Disconnect the negative (-) battery c able and partially drain the radiator.
2. Remove the air inlet duct and unplug the IAC and TPS electrical connectors.
3. Label and disconnect the vacuum and coolant lines.
4. Disconnect the accelerator, thro ttle valve (transmission control) and
cruise control cables, as applicable.
5. Remove the throttle body attaching bolts, then separate the throttle body from the plenum.
6. Discard the gasket.
To install: 7. Install the throttle body to the plenum using a new gasket. Tighten the \
bolts to specification.
8. Engage the accelerator, throttle valve and cruise control cables, as
necessary. Make sure that the link ages do not hold the throttle open.
9. Connect the vacuum and coolant lines.
10. Install the air inlet duct and plug the IAC and TPS electrical connectors
into their sockets.
11. Connect the negative (-) battery cable and refill the radiator.
12. With the engine OFF, check to s ee that the accelerator pedal is free.
Depress the pedal to the floor and release.

GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 742

Fig. 3: Throttle body assembly on 5.0L and 5.7L TPI engines
ADJUSTMENTS
IAC VALVE POSITION
The ECM will need to relearn the Idle Ai r Control (IAC) valve position anytime
battery power has been interrupted to it. A scan tool must be used on 3.1L
engines to update the ECM with the corre ct IAC valve position and provide a
stable idle speed. The IAC valve position on others can be reset by starting and
running the engine for 5 seconds, then turning the ignition OFF for 10 seconds.
Start the engine again and che ck for proper operation.

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MINIMUM IDLE SPEED
The minimum idle speed should onl
y be adjusted under two conditions:
If the throttle body has been replaced.
After every other possible cause for the in correct idle speed has been explored.
There are many possible causes for incorre ct idle speed, most of which require
a high level of diagnostic skill as well as expensive testing equipment. Check
the vehicle for vacuum leaks, incorrect valve or ignition timing, deposit
accumulation in the throttle bore or valve, sticking throttle linkage or bent throttle
valves. If the vehicle will still not idle pr operly after checking these areas, it
should be diagnosed by a professional.
1. Pierce the idle stop screw with an awl. Apply leverage to remove it.
2. Make sure the IAC valve is connect ed. Short the A and B terminals of the
ALDL connector together with a length of wire.
3. Turn the ignition to the ON positi on, but do not start the engine. Wait at
least 30 seconds before proceeding.
4. With the ignition ON, disconnect the IAC valve connector.
5. Separate the set-timing connector. Th is eliminates the possibility of
changes in engine speed due to variations of engine timing.
6. Start the engine and remove t he wire shorting the A and B terminals
together. It may be necessary to hold the throttle open slightly to prevent
the engine from stalling.
7. Allow the engine to reach no rmal operating temperature.
8. Adjust the idle speed to the following: a. 2.8L Engines - 450-550 rp m A/T or 550-650 rpm M/T
b. 3.1L Engines - Refer to the underhood emissions sticker
c. 5.0L and 5.7L TPI engines - 400-450 rpm.
If these figures differ from t hose on the underhood emissions
sticker, always follow the specifications on the emissions sticker.
9. Turn the ignition OFF and connect the IAC valve harness. On models up
to 1989, adjust the Throttle Position Sensor.
THROTTLE POSITION SENSOR (TPS) 1. Install three jumper wires betw een the TPS and the harness connector.
2. Use a digital voltmeter connected to terminals A and B of the TPS.
3. Turn the ignition switch ON , but do not start the engine.
4. Loosen the TPS attaching screws and adj ust the sensor to the following:
a. 2.8L Engines - 0.50-0.60 volts
b. 5.0L and 5.7L TPI Engines - 0.47-0.61 volts
5. Tighten the attaching screws, then check that the reading has not been
disturbed.
6. With the ignition OFF, remove the jumper wires. Reconnect the TPS
harness.

GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 747
To install:
12. Lubricate with clean engine oil, then install the injector nozzle O-rings.
13. Install the fuel rail assembly. Tilt t he assembly to install the injectors.
14. Tighten the fuel rail attachi ng bolts to specification.
15. Engage the injector electrical connectors. Rotate each injector as
required to avoid stretching the harness.
16. Connect the vacuum hose to the pressure regulator.
17. Connect the fuel feed and return lines. New O-rings must be used.
18. Install a new O-ring seal on the cold start tube. Thread the tube nut to the
fitting on the fuel rail. Use a backup wrench on the fuel rail fitting t\
o
prevent it from turning.
19. Temporarily connect the negative battery terminal. a. With the engine OF F and the ignition ON, check for fuel leaks.
Repair as necessary.
b. Disconnect the negative battery cable.
20. Install the intake plenum using new gaskets.
21. Connect the negative battery cable.

Fig. 1: Fuel rail assembly on 2.8L engines

GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 750
6. Disconnect the vacuum hose
at the pressure regulator.
7. Unplug the electrical connectors.
8. Loosen and remove the fuel rail attaching bolts.
9. Remove the fuel rail assembly from the intake manifold.
10. Discard all of the O-ring seals t hat are exposed during this procedure.
To install: 11. Lubricate with clean engine oil, then install the injector nozzle O-rings.
12. Install the fuel rail assembly in the intake manifold.
13. Tighten the fuel rail attachi ng bolts to specification.
14. Engage the injector electrical connectors. Rotate each injector as
required to avoid stretching the harness.
15. Connect the vacuum hose to the pressure regulator.
16. Connect the fuel feed and return lines. New O-rings must be used.
17. Temporarily connect the negative battery terminal. a. With the engine OF F and the ignition ON, check for fuel leaks.
Repair as necessary.
b. Disconnect the negative battery cable.
18. Install the intake plenum and runners. Use new gaskets.
19. Connect the negative battery cable.
FUEL PRESSURE REGULATOR
REMOVAL & INSTALLATION
2.8L AND 3.1L ENGINES
The pressure regulator and the fuel rail are serviced as a complete assembly
only. DO NOT attempt to remove the regulator cove r from the fuel rail.
5.0L AND 5.7L TPI ENGINES 1. Disconnect the negative battery cable.
2. Relieve the fuel system pressure.
3. Remove the intake plenum and runners.
4. Remove the fuel rail assembly.
5. Remove the rear crossover re tainer and base attaching screw.
6. Remove the rear crossover tube and O-ring from the regulator base.
Discard the O-ring.
7. Remove the pressure regulator bracket.
8. Remove the pressure r egulator base-to-rail screw.
9. Separate the regulator base from the fuel rail, then disconnect from the
fuel outlet tube.
10. Remove the fuel outle t tube O-ring and discard.
11. Remove the regulator bas e-to-fuel rail connector.
To install: 12. Lubricate and install new regul ator base-to-fuel rail O-rings.

GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 753
THROTTLE POSITION SENSOR (TPS)
REMOVAL & INSTALLATION
1. Disconnect the negative battery cable.
2. Detach the electrical connector from the sensor.
3. Remove the attaching screws, lockw ashers and retainers. Some models
use a seal between the throttle body and the sensor, do not lose this! \
4. Remove the throttle position sensor.
To install: 5. Install the throttle position sensor seal, if applicable.
6. With the throttle valve in the norma l closed idle position, install the
sensor on the throttle body assembly. Make sure the sensor pickup lever
is properly located on the th rottle actuator lever.
7. Install the retainers, screws and lockwashers using a thread locking
compound. On models up to 1989, DO NOT tighten the screws until the
sensor is adjusted. Follow the procedures outlined earli er in this section.
COLD START VALVE
REMOVAL & INSTALLATION 1. Disconnect the negative battery cable.
2. Relieve the fuel system pressure.
3. Remove the intake manifold plenum.
4. Unplug the electrical connection.
5. Clean the fuel rail around the cold start valve tube fitting.
6. Remove the tube fitting from t he fuel rail. Use a backup wrench to
prevent it from turning.
7. Remove the cold start valve retain ing bolt and remove the valve from the
intake manifold.
To install: 8. Use new O-rings and install the valve and bolt.
9. Connect the wiring harness.
10. Connect the cold start tube at the f uel rail. Use a wrench to prevent it
from turning.
11. Install the intake manifold plenum.
12. Connect the negative battery cable. With the engine OFF and the ignition
ON, check for fuel leaks.

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A more advanced set of tools, suit
able for tune-up work, can be drawn up
easily. While the tools are slightly more sophisticated, they need not be
outrageously expensive. There are severa l inexpensive tach/dwell meters on
the market that are every bit as good for the average mechanic as a
professional model. Just be sure that it goes to a least 1200-1500 rpm on the
tach scale and that it works on 4, 6 and 8-cylinder engines. The key to these
purchases is to make them with an eye towards adaptability and wide range. A
basic list of tune-up tools could include:
• Tach/dwell meter.
• Spark plug wrench and gapping tool.
• Feeler gauges for valve adjustment.
• Timing light.
The choice of a timing light should be made carefully. A light which works on the
DC current supplied by the vehicle's battery is the best choice; it should have a
xenon tube for brightness. On any vehi cle with an electronic ignition system, a
timing light with an inductive pickup that clamps around the No. 1 spark plug
cable is preferred.
In addition to these basic tools, ther e are several other tools and gauges you
may find useful. These include:
• Compression gauge. The screw-in type is slower to use, but eliminates
the possibility of a faulty r eading due to escaping pressure.
• Manifold vacuum gauge.
• 12V test light.
• A combination volt/ohmmeter
• Induction Ammeter. This is used for determining whether or not there is
current in a wire. These are handy fo r use if a wire is broken somewhere
in a wiring harness.
As a final note, you will probably find a torque wrench necessary for all but the
most basic work. The beam type models are perfectly adequate, although the
newer click types (breakaway) are eas ier to use. The click type torque
wrenches tend to be more expensive. Also keep in mind that all types of torque
wrenches should be periodically checked a nd/or recalibrated. You will have to
decide for yourself which better fits your pocketbook, and purpose.
SPECIAL TOOLS
Normally, the use of special factory tool s is avoided for repair procedures, since
these are not readily available for the do-it-yourself mechanic. When it is
possible to perform the job with more co mmonly available tools, it will be
pointed out, but occasionally, a special t ool was designed to perform a specific
function and should be used. Before s ubstituting another tool, you should be
convinced that neither your safety nor the performance of the vehicle will be
compromised.