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GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 640
The tachometer terminal should never
be allowed to touch ground, as damage
to the computer control module and/or ignition coil assembly can result.
CONNECTORS
When disengaging connectors, do not use a screw driver or other tool to release
the locking tab, as this mi ght break the connector.
SYSTEM TESTERS
Instruments designed specific ally for testing HEI or C
3I systems are available
from several tool manufactur ers. Some of these will even test the module itself.
However, the tests given in the followin g section will require only an ohmmeter
and a voltmeter.
TESTING
The symptoms of a defective component within the HEI or C
3I system are
exactly the same as those you woul d encounter in a conventional system.
Some of these symptoms are:
• Hard or no starting
• Rough Idle
• Poor fuel economy
• Engine misses under load or while accelerating
PRELIMINARY CHECKS
If you suspect a problem in your igniti on system, there are certain preliminary
checks which you should carry out befor e you begin to check the electronic
portions of the system. First, it is extrem ely important to make sure the vehicle
battery is in a good state of charge. A defective or poorly charged battery will
cause the various components of the ignition system to read incorrectly when
they are being tested. Second, make su re all wiring connections are clean and
tight, not only at the battery, but also at the distributor cap (if so equipped),
ignition coil, camshaft and/or crankshaft sensors (if so equipped) and at the
control module.
Since the only difference between these ignition systems lies before the spark
plug wiring, it is important to check the secondary ig nition circuit first. If the
secondary circuit checks out properly (ther e is spark), then the engine condition
is probably not the fault of the ignition system. To check the secondary ignition
system, perform a simple spark test. Remove one of the plug wires and insert
some sort of extension in the plug socket. An old spark plug with the ground
electrode removed makes a good extension. Hold the wire and extension using
an insulated tool (NOT BY HAND) about
1/4 in. (6mm) away from the block and
crank the engine. If a normal spark occurs, then the problem is most likely not in
the ignition system. Check for fuel system problems, or fouled spark plugs.
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7. If any results of the 3 tests lis
ted above do not agree with the desired
readings, replace the ignition coil.
INTERNALLY MOUNTED 1. Connect an ohmmeter between the TACH and BAT terminals on the
ignition coil. The primary coil resi stance should be less than ohms;.
2. To check the coil secondary resistance, connect an ohmmeter between the high tension terminal and the BAT terminal. Note the reading.
Connect the ohmmeter between the high tension terminal and the TACH
terminal. Note the reading. The resi stance in both cases should be
6,000-30,000 ω. Be sure to test between the high tension terminal and
both the BAT and TACH terminals.
3. Replace the coil only if the reading s in Step 1 and Step 2 are infinite.
These resistance checks will not disclose shorted coil windings. This condition
can only be detected with scope analysis or a suitably designed coil tester. If
these instruments are unavaila ble, replace the coil with a known good coil as a
final coil test.
Fig. 2: Testing interna lly mounted ignition coil
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GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 644
PICKUP COIL
1. To test the pickup coil, firs t disconnect the white and green module
leads. Set the ohmmeter on the high scale and connect it between a
ground and either the wh ite or green lead. Any resistance measurement
less than infinity requires repl acement of the pickup coil.
Fig. 3: Testing Pickup coil - Test 1 should read infinite at all times. Test 2 should
read a steady value of 500-1500 ohms.
2. Pickup coil continuity is test ed using an ohmmeter (on low range)
between the white and gr een leads. Normal resistance is 500-1,500ω. If
a vacuum unit is used, move the vacuum advance arm while performing
this test. This will detect any break in coil continuity. Such a condition can
cause intermittent misfiring. Replac e the pickup coil if the reading is
outside the specified limits.
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VALVE LASH
All models utilize a hydraulic valve lifter system to obtain zero lash. No periodic
adjustment is necessary. An initial adjustm
ent is required anytime that the lifters
are removed or the valve tr ain is disturbed. This procedure is covered in Engine
& Engine Overhaul .
IDLE SPEED AND MIXTURE ADJUSTMENTS
Mixture adjustments are factory set and sealed; no adjustment attempt should
be made, except by an aut horized GM dealer or reputable shop equipped with
the necessary equipment.
IDLE SPEED
2-BBL CARBURETOR
WITHOUT AIR CONDITIONING
The engine must be running in "Closed Loop" mode (engine fully warmed) when
making all idle speed adjustments. In this mode, the oxygen sensor affects
control of the fuel delivery.
1. Refer to the emission label on the vehicle and prepare the engine for
adjustments (set the timing). Remove the air cleaner and set the parking
brake. Connect a tachometer to the distributor connector.
2. Place the transmission in DRIVE for automatic transmission, or
NEUTRAL for manual transmission; make sure that the solenoid is
energized.
3. Open the throttle slightly to allow the solenoid plunger to extend. Adjust
the curb idle speed to the specified rpm by turning the solenoid screw.
4. De-energize the solenoid by disconnecting the electrical lead.
5. Set the basic idle speed rpm by turning the idle speed screw. After
adjustment, reconnect the solenoid electrical lead.
6. Remove the tachometer and install the air cleaner.
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Fig. 1: Idle speed adjustm ents - 2-bbl carburetor (without air conditioning)
WITH AIR CONDITIONING
The engine must be running in "Closed Loop" mode (engine fully warmed) when
making all idle speed adjustments. In this mode, the oxygen sensor affects
control of the fuel delivery.
1. Refer to the emission label on the vehicle and prepare the engine for
adjustments (set the timing). Remove the air cleaner and set the parking
brake. Connect a tachometer to the distributor connector.
2. Place the transmission in DRIVE for automatic transmission, or
NEUTRAL for manual transmission. Tu rn the air conditioning OFF and
set the curb idle speed by turning the idle speed screw.
3. Disconnect the electrical lead at the A/C compressor, then turn the A/C
switch ON.
4. With the solenoid e nergized, open the throttle slightly to allow the
solenoid plunger to extend.
5. Turn the solenoid screw to adjust to the specified rpm. After adjustment,
reconnect the A/C compressor lead and turn the air conditioning OFF.
6. Remove the tachometer and install the air cleaner.
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Fig. 2: Idle speed adjustm ents - 2-bbl carburetor (with air conditioning)
4-BBL CARBURETOR
WITHOUT AIR CONDITIONING
The engine must be running in "Closed Loop" mode (engine fully warmed) when
making all idle speed adjustments. In this mode, the oxygen sensor affects
control of the fuel delivery.
1. Refer to the emission label on the vehicle and prepare the engine for
adjustments (set the timing). Se t the parking brake. Connect a
tachometer to the dist ributor connector.
2. Place the transmission in DRIVE for automatic transmission, or
NEUTRAL for manual transmission.
3. De-energize the idle speed solenoid by disconnecting the electrical lead.
4. Set the basic idle speed rpm by turning the idle speed screw.
5. Connect a jumper wire from a 12-vo lt power supply to the solenoid.
6. Open the throttle partially to ensure that the solenoid plunger is fully
extended, and allow the throttle lever to close on the plunger.
7. Turn the solenoid plunger to adj ust to the specified rpm. After
adjustment, disconnect the jumper wire and reconnect the solenoid
electrical lead.
8. Remove the tachometer and install the air cleaner.
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Fig. 3: Idle speed adjustm ents - 4-bbl carburetor
WITH AIR CONDITIONING
The engine must be running in "Closed Loop" mode (engine fully warmed) when
making all idle speed adjustments. In this mode, the oxygen sensor affects
control of the fuel delivery.
1. Refer to the emission label on the vehicle and prepare the engine for
adjustments (set the timing). Se t the parking brake. Connect a
tachometer to the dist ributor connector.
2. Place the transmission in DRIVE for automatic transmission, or
NEUTRAL for manual transmission. Tu rn the air conditioning OFF.
3. De-energize the idle speed solenoid by disconnecting the electrical lead.
4. Set the basic idle speed rpm by turning the idle speed screw. After
adjustment, reconnect the solenoid electrical lead.
5. Disconnect the electrical lead from the A/C compressor and turn the A/C
switch ON.
6. Open the throttle partially to ensure that the solenoid plunger is fully
extended, and allow the throttle lever to close on the plunger.
7. Turn the solenoid plunger to adj ust to the specified rpm. After
adjustment, reconnect the A/C co mpressor lead and turn the air
conditioning OFF.
8. Remove the tachometer and install the air cleaner.
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Fig. 3: Be careful not to spill fuel when removing the pump from the engine
TESTING
To determine if the pump is in good condition, tests for both volume and
pressure should be performed. The test s are made with the pump installed, the
engine at normal operating temperatur e and operating at idle speed. Never
replace a fuel pump without first performing these simple tests.
Ensure the fuel filter has been changed at the specified interval. If in doubt,
install a new filter first. Always check fo r broken or deteriorated fuel hoses. If a
line has a crack or split, the pump may be operating properly, but the pump will
only draw air, not fuel.
PRESSURE TEST
1. Disconnect the fuel line at the carburetor, then connect a fuel pump
pressure gauge. Ensure the carburet or float bowl has a sufficient amount
of gasoline.
2. Start the engine and c heck the pressure with the engine at idle. If the
pump has a vapor return hose, squeeze it off so that an accurate reading
can be obtained. Pressure should be 5
1/2-61/2 psi.
3. If the pressure is incorrect, replace t he pump. If it is within specifications,
go on to the volume test.
VOLUME TEST