GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 547
EXHAUST GAS RECIRCULATION (EGR) SYSTEM
OPERATION
All models are equipped with
this system, which consists of a metering valve, a
vacuum line to the carburet or or intake manifold, and cast-in exhaust passages
in the intake manifold. The EGR valve is controlled by vacuum, which opens
and closes in response to the vacuum signals to admit exhaust gases into the
air/fuel mixture. The exhaust gases lower peak combustion temperatures,
reducing the formation of NOx. The valve is closed at idle and wide open
throttle, but is open between the two extreme positions.
There are actually four types of EGR systems: Ported, Positive Back-Pressure,
Negative Backpressure and Digital. The pr inciple of all the systems are the
same; the only difference is in the me thod used to control how the EGR valve
opens.
Too much EGR flow at idle, cruise or during cold operation may result in the
engine stalling after cold start, the engine stalling at idle after deceleration,
vehicle surge during cruise and rough idle . If the EGR valve is always open, the
vehicle may not idle. Too little or no EGR flow allows combustion temperatures
to rise, which could result in spar k knock (detonation), engine overheating
and/or emission test failure.
A Thermal Vacuum Switch (TVS) or vacuum control solenoid may sometimes\
be used in combination with the EGR va lve. The TVS will close off vacuum
during cold operation. A va cuum control solenoid uses Pulse Width Modulation
(PWM) to turn the solenoid ON and OFF numerous times a second and varies
the amount of ON time (pulse width) to vary the amount of ported vacuum
supplied the EGR valve.
PORTED VALVE
In the ported system, the amount of ex haust gas admitted into the intake
manifold depends on a ported vacuum signal. A ported vacuum signal is one
taken from the carburetor above the th rottle plates; thus, the vacuum signal
(amount of vacuum) is dependent on how far the throttle plates are opened.
When the throttle is closed (idle or dec eleration) there is no vacuum signal.
Thus, the EGR valve is closed, and no exhaust gas enters the intake mani\
fold.
As the throttle is opened, a vacuum is produced, which opens the EGR valve,
admitting exhaust gas into the intake manifold.
POSITIVE BACKPRE SSURE VALVE
This valve operates the same as the ported, except, it has an internal air bleed
that acts as a vacuum regulator. T he bleed valve controls the amount of
vacuum inside the vacuum chamber duri ng operation. When the valve receives
sufficient exhaust backpressure through the hollow shaft, it closes the bleed; at
this point the EGR valve opens.
GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 581
Fig. 1: Coolant temperature sensor. The in take air temperature sensor is similar
in appearance
IDLE AIR CONTROL (IAC) VALVE
OPERATION
Engine idle speeds are controlled by the ECM through the IAC valve mounted
on the throttle body. The ECM sends volt age pulses to the IAC motor windings
causing the IAC motor shaft and pintle to move IN or OUT a given distance
(number of steps) for each pulse (called counts). The movement of the pintle
controls the airflow around the throttle plat e, which in turn, controls engine idle
speed. IAC valve pintle position counts ca n be observed using a scan tool. Zero
counts correspond to a fully closed passage, while 140 counts or more
corresponds to full flow.
Idle speed can be categorized in 2 ways : actual (controlled) idle speed and
minimum idle speed. Contro lled idle speed is obtained by the ECM positioning
the IAC valve pintle. Resulting idle speed is determined by total air fl\
ow
(IAC/passage + PCV + throttle valve + ca librated vacuum leaks). Controlled idle
speed is specified at normal operating c onditions, which consists of engine
coolant at normal operating temper ature, air conditioning compressor OFF,
manual transmission in neutral or automatic transmission in D.
Minimum idle air speed is set at t he factory with a stop screw. This setting
allows a certain amount of air to bypas s the throttle valves regardless of IAC
valve pintle positioning. A co mbination of this air flow and IAC pintle positioning
allows the ECM to control engine idle speed. During normal engine idle
operation, the IAC valve pintle is positioned a calibrated number of steps
(counts) from the seat. No adjustment is required during routine maintenance.
Tampering with the minimum idle speed adjustment may result in premature
failure of the IAC valve or imprope rly controlled engine idle operation.
GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 651
Fig. 6: Removing the distri butor cap. Notice that all towers on cap are labeled
with the corresponding engine cylinder number.
ROTOR 1. Disconnect the negative battery cable.
2. Remove the distributor cap.
3. Unscrew the two rotor attaching screws and then lift off the rotor.
4. For installation, make sure the roto r is positioned in the correct direction
and tighten the retaining screws.
CAPACITOR
The capacitor, if equipped, is part of the ignition coil wire harness assembly.
Since the capacitor is used only for radio noise suppres sion, it will seldom need
replacement.
1. Disconnect the negative battery cable.
2. Remove the distributor cap and rotor.
3. Remove the capacitor attaching screws and unplug the connector from
the module. Remove the module.
To install: 4. Plug the connector into the capacitor. Install the capacitor and secure in
place using the mounting screws. Be sure the ground lead is under the
screw.
5. Install the rotor and distributor cap.
GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 708
rapidly. Failure to replace all parts s
upplied with the kit (especially gaskets) can
result in poor performance later.
Some carburetor manufacturers supply overhaul kits for three basic types:
minor repair; major repair; and gasket kits. Certain parts may be expected in
most kits based on the desired degree of overhaul.
MINOR REPAIR KITS
• All gaskets
• Float needle valve
• All diaphragms
• Spring for the pump diaphragm
MAJOR REPAIR KITS
• All jets and gaskets
• All diaphragms
• Float needle valve
• Pump ball valve
• Float
• Complete intermediate rod
• Intermediate pump lever
• Some cover hold-down screws and washers
GASKET KITS
• All gaskets
Efficient carburetion depends greatly on careful cleaning and inspection during
overhaul, since dirt, gum, water, or varnis h in or on the carburetor parts are
often responsible for poor performance.
Overhaul your carburetor in a clean, dust-free area. Carefully disassemble the
carburetor, referring often to the explod ed views and directions packaged with
the rebuilding kit. Keep all similar and look-alike parts separated during
disassembly and cleaning to avoid accidental interchange during assembly\
.
Make a note of all jet sizes.
When the carburetor is disassembled, wash all parts (except diaphragms,
electric components, pump pl unger, and any other plastic, leather, fiber, or
rubber parts) in clean carbur etor solvent. Do not leave parts in the solvent any
longer than is necessary to sufficiently loosen the deposits. Excessive cleaning
may remove the special finish from the float bowl and choke valve bodies,
leaving these parts unfit for service. Rinse all parts in clean solvent and blow
them dry with compressed air or allow them to air dry. Wipe clean all cork,
plastic, leather, and fiber parts with a clean, lint-free cloth.
Blow out all passages and jets with comp ressed air and be sure that there are
no restrictions or blockages. Never use wi re or similar tools to clean jets, fuel
GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 709
passages, or air bleeds. Clean all jets and va
lves separately to avoid accidental
interchange.
Check all parts for wear or damage. If we ar or damage is found, replace the
defective parts. Especially check the following:
1. Check the float needle and seat for wear.
2. Check the float hinge pin for wear and the float(s) for dents or distortion.
Replace the float if fuel has leaked into it.
3. Check the throttle and choke sha ft bores for wear or an out-of-round
condition. Damage or wear to the thro ttle arm, shaft, or shaft bore will
often require replacement of the throttle body. These parts require a
close tolerance of fit; wear may allow air leakage, which could affect
starting and idling.
Throttle shafts and bushings are not included in overhaul kits. They can be
purchased separately or repaired by a qualified carburetor overhaul shop.
4. Inspect the idle mixt ure adjusting needles for bu rrs or grooves. Any such
condition requires replacement of t he needle, since you will not be able
to obtain a satisfactory idle.
5. Test the accelerator pump check va lves. They should pass air one way
but not the other. Test for proper s eating by blowing and sucking on the
valve. Replace the valve check ball and spring as necessary. If the valve
is satisfactory, wash the valve part s again to remove breath moisture.
6. Check the bowl cover for war ped surfaces with a straightedge.
7. Closely inspect the accelerato r pump plunger for wear and damage,
replacing as necessary.
8. After the carburetor is assembled, check the choke valve for freedom of
operation.
9. Check, repair or replace parts, if the following problems are encountered:
FLOODING
• Inspect the float valve and seat for dirt, deep wear grooves, scores and
improper sealing
• Inspect the float valve pull clip for proper installation; be careful no\
t to
bend the pull clip
• Inspect the float, the float arms and the hinge pin for distortion, binds,
and burrs. Check the density of the mate rial in the float; if heavier than
normal, replace the float
• Clean or replace the fuel inlet f ilter and check the valve assembly
HESITATION
• Inspect the pump plunger for cracks, scores or cup excessive wear. A
used pump cup will shrink w hen dry. If dried out, soak in fuel for 8 hours
before testing
• Inspect the pump duration and return springs for weakness or distortion \
GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 761
MAINTENANCE OR REPAIR?
Maintenance includes routine inspecti
ons, adjustments, and replacement of
parts which show signs of normal wear . Maintenance compensates for wear or
deterioration. Repair implies that someth ing has broken or is not working. A
need for a repair is often caused by lack of maintenance. for example: draining
and refilling automatic transmission fl uid is maintenance recommended at
specific intervals. Failure to do this can shorten the life of the
transmission/transaxle, requiring very expen sive repairs. While no maintenance
program can prevent items from eventually breaking or wearing out, a general
rule is true: MAINTENANCE IS CHEAPER THAN REPAIR.
Two basic mechanic's rules should be mentioned here. First, whenever the left
side of the vehicle or engine is refe rred to, it means the driver's side.
Conversely, the right side of the vehi cle means the passenger's side. Second,
screws and bolts are removed by turn ing counterclockwise, and tightened by
turning clockwise unless specifically noted.
Safety is always the most important rule. Constantly be aware of the dangers
involved in working on an automobile and take the proper precautions. Please
refer to the information in this se ction regarding SERVICING YOUR VEHICLE
SAFELY and the SAFETY NOTICE on the acknowledgment page.
AVOIDING THE MOST COMMON MISTAKES
Pay attention to the instructions prov ided. There are 3 common mistakes in
mechanical work:
1. Incorrect order of assembly, di sassembly or adjustment. When taking
something apart or putting it toget her, performing steps in the wrong
order usually just costs you ex tra time; however, it CAN break
something. Read the entire proc edure before beginning. Perform
everything in the order in which the instructions say you should, even if
you can't see a reason for it. When you' re taking apart something that is
very intricate, you might want to draw a picture of how it looks when
assembled in order to make sure you get everything back in its proper
position. When making adjustments, per form them in the proper order.
One adjustment possibly will affect another.
2. Overtorquing (or undertorquing). While it is more common for overtorquing to cause damage, undertorquing may allow a fastener to
vibrate loose causing serious dam age. Especially when dealing with
aluminum parts, pay attention to tor que specifications and utilize a torque
wrench in assembly. If a torque figure is not available, remember that if
you are using the right tool to perfo rm the job, you will probably not have
to strain yourself to get a fast ener tight enough. The pitch of most
threads is so slight that the te nsion you put on the wrench will be
multiplied many times in actual fo rce on what you are tightening.
There are many commercial products avai lable for ensuring that fasteners won't
come loose, even if they are not torqued just right (a very common brand is
GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 801
Fig. 3: Note location of power steering fluid on indicator. Do not overfill power
steering pump when adding fluid.
Power steering fluid level s hould be checked at least twice a year. To prevent
possible overfilling, check the fluid le vel only when the fluid has warmed to
operating temperatures and the wheels are turned straight ahead. If the level is
low, fill the pump reservoir until the flui d level measures between the COLD and
HOT marks on the reservoir dipstick. Low fluid level usually produces a
moaning sound as the wheels are turned (especially when standing still or
parking) and increases st eering wheel effort.
STEERING GEAR
FLUID RECOMMENDATIONS
The 1982-92 vehicles are equipped with a pow er steering gear. All vehicles use
GM power steering fluid, or equivalent.
CHASSIS GREASING
Chassis lubrication can be performed with a pressurized grease gun or by using
a hand-operated grease gun. Wipe the grease fittings clean before greasing in
order to prevent the possibility of fo rcing any dirt into the component.
GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 810
Fig. 14: After the bearings are adjusted, install the dust cap by gently tapping on
the flange - DO NOT damage the c ap by hammering on the center
JUMP STARTING A DEAD BATTERY
Whenever a vehicle is jump started, pr ecautions must be followed in order to
prevent the possibility of personal inju ry. Remember that batteries contain a
small amount of explosive hydrogen gas which is a by-product of battery
charging. Sparks should always be av oided when working around batteries,
especially when attaching jumper cabl es. To minimize the possibility of
accidental sparks, follow the procedure carefully.
Fig. 1: Connect the jumper cables to the batteries and engine in the order
shown