ignition CHEVROLET CAMARO 1982 Repair Guide

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recommended to have a qualified technici
an perform any further testing, if
needed.
FIELD SERVICE MODE
On fuel injected models, if the ALDL terminal B is grounded to terminal A with
the engine running, the system enters the Field Service Mode. In this mode, the
MIL will indicate whether the system is operating in open loop or closed loop.
If working in open loop, t he MIL will flash rapidly 2
1/2 times per second. In
closed loop, the flash rate slows to once per second. Additionally, if the system
is running lean in closed loop, the lamp will be off most of the cycle. A rich
condition in closed loop will cause the lamp to remain lit for most of the one
second cycle.
When operating in the Field Service M ode, additional codes cannot be stored
by the ECM. The closed loop timer is bypassed in this mode.
CLEARING CODES
Stored fault codes may be erased from me mory at any time by removing power
from the ECM for at least 30 seconds. It may be necessary to clear stored
codes during diagnosis to check for any re currence during a test drive, but the
stored should be written dow n when retrieved. The codes may still be required
for subsequent troubleshooting. Whenever a repair is complete, the stored
codes must be erased and the vehicle te st driven to confirm correct operation
and repair.
The ignition switch must be OFF any ti me power is disconnected or restored to
the ECM. Severe damage may result if this precaution is not observed.
Depending on the electric di stribution of the particular vehicle, power to the
ECM may be disconnected by removing the ECM fuse in the fusebox or
disconnecting the inline EC M power lead at the positive battery terminal.
Disconnecting the negative battery cable to clear codes will achieve the desired
result, but this will also clear other me mory data in the vehicle such as radio
presets or seat memory.

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SPARK PLUG HEAT RANGE
Spark plug heat range is
the ability of the plug to dissipate heat. The longer the
insulator (or the farther it extends in to the engine), the hotter the plug will
operate; the shorter the insulator (the cl oser the electrode is to the block's
cooling passages) the cooler it will operate. A plug that absorbs little heat and
remains too cool will quickly accumulate deposits of oil and carbon since it is
not hot enough to burn them off. This leads to plug fouling and consequently to
misfiring. A plug that absorbs too much heat will have no deposits but, due to
the excessive heat, the electrodes will burn away quickly and might possibly
lead to preignition or other ignition probl ems. Preignition takes place when plug
tips get so hot that they gl ow sufficiently to ignite the air/fuel mixture before the
actual spark occurs. This early igniti on will usually cause a pinging during low
speeds and heavy loads.

Fig. 3: Spark plug heat range
The general rule of thumb for choosing the correct heat range when picking a
spark plug is: if most of your driving is long distanc e, high speed travel, use a
colder plug; if most of your driving is stop and go, use a hotter plug. Original
equipment plugs are general ly a good compromise between the 2 styles and
most people never have the need to change their plugs from the factory-
recommended heat range.
REMOVAL & INSTALLATION
A set of spark plugs usually requi res replacement after about 20,000-30,000
miles (32,000-48,000 km), depending on y our style of driving. In normal
operation plug gap increases about 0.001 in. (0.025mm) for every 2500 miles
(4000 km). As the gap increases, the plug' s voltage requirement also increases.
It requires a greater voltage to jump t he wider gap and about two to three times

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as much voltage to fire the plug at hi
gh speeds than at idle. The improved
air/fuel ratio control of modern fuel injection combin ed with the higher voltage
output of modern ignition systems will often allow an engine to run significantly
longer on a set of standard spark plugs, but keep in mind that efficiency will
drop as the gap widens (along wit h fuel economy and power).
When you're removing spark plugs, work on one at a time. Don't start by
removing the plug wires all at once, because, unless you number them, they
may become mixed up. Take a minute before you begin and number the wires
with tape.
1. Disconnect the negative battery cabl e, and if the vehicle has been run
recently, allow the engine to thoroughly cool.
2. Carefully twist the spark plug wire boot to loosen it, then pull upward and
remove the boot from the plug. Be su re to pull on the boot and not on the
wire, otherwise the connector locat ed inside the boot may become
separated.
3. Using compressed air, blow any water or debris from the spark plug well
to assure that no harmful contam inants are allowed to enter the
combustion chamber when the spark plug is removed. If compressed air
is not available, use a rag or a brush to clean the area.
Remove the spark plugs when the engine is cold, if possible, to prevent damage
to the threads. If removal of the plugs is difficult, apply a few drops of
penetrating oil or silicone spray to t he area around the base of the plug, and
allow it a few minutes to work.
4. Using a spark plug socket that is equipped with a rubber insert to
properly hold the plug, turn the spar k plug counterclockwise to loosen
and remove the spark pl ug from the bore.
WARNING - Be sure not to use a flexible extension on the socket. Use of a
flexible extension may allow a shear fo rce to be applied to the plug. A shear
force could break the plug off in the cylinder head, leading to costly a\
nd
frustrating repairs.
To install:
5. Inspect the spark plug boot for t ears or damage. If a damaged boot is
found, the spark plug wire must be replaced.
6. Using a wire feeler gauge, check and adjust the spark plug gap. When
using a gauge, the proper size shoul d pass between the electrodes with
a slight drag. The next larger size should not be able to pass while the\

next smaller size should pass freely.
7. Carefully thread the plug into the bor e by hand. If resistance is felt before
the plug is almost completely th readed, back the plug out and begin
threading again. In small, hard to r each areas, an old spark plug wire and
boot could be used as a th reading tool. The boot will hold the plug while
you twist the end of the wire and t he wire is supple enough to twist
before it would allow t he plug to crossthread.

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ELECTRONIC IGNITION SYSTEM

GENERAL INFORMATION
The High Energy Ignition (HEI) system
controls the fuel combustion by
providing a spark to ignite the compress ed air/fuel mixture at the correct time.
To provide improved engine performance, fuel economy, and control of exhaust
emissions, the engine contro l module (ECM) controls distributor spark advance
(timing) with an ignition control system.
The distributor may have an internal, or ex ternal ignition coil. To be certain of
the type coil used for your vehicle, vis ually inspect the ignition system. If the
ignition coil is inside the distributor c ap, it connects through a resistance brush
to the rotor. If your vehicle is equipped with an external ignition coil, it connects
to the rotor through a high tension wire.

Fig. 1: Distributor with exterior ignition coil - 1987 vehicle shown
The distributor contains the ignition c ontrol module, and the magnetic triggering
device. The magnetic pickup assembly contains a permanent magnet, a pole
piece with internal "teeth", and a pickup co il (not to be confused with the ignition
coil).
All spark timing changes are done electr onically by the engine control module
(ECM) which monitors information from various engine sensors. The ECM
computes the desired spark timing and t hen signals the distributor ignition
module to change the timing accordingly. No vacuum or mechanical advance
systems are used.

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In the HEI system, as in other electr
onic ignition systems, the breaker points
have been replaced wit h an electronic switch - a tr ansistor - which is located
within the ignition module. This switching transistor pe rforms the same function
the points did in a conventi onal ignition system; it simply turns the coil's primary
current on and off at the correct time. Essentially, electronic and conventional
ignition systems operate on t he same principle.
The module which houses the switching transistor is controlled (turned on and
off) by a magnetically gener ated impulse induced in the pickup coil. When the
teeth of the rotating timer align with t he teeth of the pole piece, the induced
voltage in the pickup coil signals the elec tronic module to open the coil primary
circuit. The primary current then decreases, and a high voltage is induced in the
ignition coil secondary windings, which is then directed through the rotor and
high voltage leads (spark plug wires) to fire the spark plugs.
In essence, the pickup coil module system simply replaces the conventional
breaker points and condenser. The condenser found within the distributor is for
radio suppression purposes only and has nothing to do with the ignition
process. The ignition module automatically controls the dwell period, increasing
it with increasing en gine speed. Since dwell is co ntrolled in this manner, it
cannot be adjusted. The module itse lf is non-adjustable/non-repairable and
must be replaced if found defective.
SYSTEM PRECAUTIONS
Before proceeding with troubleshooting, ta ke note of the following precautions:
TIMING LIGHT USE
Care should be exercised when connec ting a timing light or other pick-up
equipment. Do not force anything between the boots and wiring, or through the
silicone jacket. Connections should be made in parallel using an adapter.
Inductive pickup timing lights are the bes t kind to use with the ignition systems
covered by this information.
SPARK PLUG WIRES
The plug wires used with these systems are of a different construction than
conventional wires. When replacing them, make sure you get the correct wires,
since conventional wires will not carry the voltage. Also, handle the wires
carefully to avoid cracking or splitti ng them, and NEVER pierce the wires.
TACHOMETER USE
Not all tachometers will operate or indi cate correctly when used on an HEI or
C
3I system. While some tachometers ma y give a reading, this does not
necessarily mean the reading is correct. In addition, some tachometers hook up
differently from others. If you cannot fi gure out whether or not your tachometer
will work on your car, check with the tachometer manufacturer.

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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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If, however, there is no spark or a weak
spark, then further ignition system
testing will have to be done. Troubleshooting techniques fall into various
categories, depending on t he nature of the problem and the system being
tested. Categories will include symptom s such as the engine cranks, but will not
start or the engine runs rough.
HEI SYSTEM
When testing the HEI system, there are 2 major categories of problems, (1)
Engine cranks, but will not star t or (2) Engine runs, but runs rough or cuts out.
If the engine will not start, perform a spar k test as described earlier. This will
narrow the problem area down considerab ly. If no spark occurs, check for the
presence of normal battery voltage at the battery ( BAT) terminal on the ignition
coil. The ignition switch must be in the ON position for this test. Either a
voltmeter or a test light wire may be us ed for this test. Connect the test light
wire to ground and the probe end to the BAT terminal at the coil. If the light
comes on, you have voltage to the distribut or and/or spark plug wires. If the light
fails to come on, this indicates an open circuit in the ignition primary wiring
leading to the distributor. In this case , you will have to check wiring continuity
back to the ignition switch using a test li ght. If there is battery voltage at the BAT
terminal, but no spark at the plugs, t hen the problem probably lies within the
distributor assembly.
If, on the other hand, the engine starts, but runs roughly or cuts out, make sure
the plug wires are in good shape first. There should be no obvious cracks or
breaks. You can check the plug wires with an ohmmeter, but do not pierce the
wires with a probe. Check the chart for th e correct plug wire resistance. If the
plug wires are OK, remove the cap asse mbly and check for moisture, cracks,
chips, or carbon tracks, or any other hi gh voltage leads or failures. Replace the
cap if any defects are found. Make su re the timer wheel rotates when the
engine is cranked.
If the trouble has been narrowed down to t he units within the distributor, the
following tests can help pinpoint the defective component. An ohmmeter with
both high and low ranges shou ld be used. These tests are made with the cap
assembly removed and the battery wir e disconnected. If a tachometer is
connected to the TACH terminal, disconnect it before making these tests.
IGNITION COIL
EXTERNALLY MOUNTED 1. Disconnect the coil wires and se t the ohmmeter on the high scale.
2. Connect the ohmmeter to the ignition co il as illustrated in Step 1 of the
accompanying figure.
3. The ohmmeter should read near infinite or very high.

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Fig. 1: Testing exte rnal ignition coil
4. Next, set the ohmmete r to the low scale and connect test leads as
illustrated in Step 2 of t he accompanying figure.
5. The reading should be very low or zero.
6. Now set the ohmmeter on the high scale and connect test leads as illustrated in Step 3 of the accom panying figure. The ohmmeter should
not read infinity.

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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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3. If no defects have been found at this
time, and you still have a problem,
then the module will have to be che cked. If you do not have access to a
module tester, the only possible alter native is a substitution test. If the
module fails the substitution test, replace it.
COMPONENT REPLACEMENT

CAUTION - When handling secondar y spark plug leads with the engine running
or starting, insulated pliers must be used and care exercised to prevent a
possible electrical shock.
HEI SYSTEM
IGNITION COIL
EXTERNALLY MOUNTED
1. Disconnect the negative battery cable.
2. Disconnect the ignition coil wire from the coil. Do so by pulling on the
boot of the wire while twisting it.
3. Disconnect the harness connecto r from the ignition coil.
4. Remove the coil mounting screws and the ignition coil. If necessary, drill
out and remove the rivets holding the coil to the bracket.
To install: 5. Place the ignition coil in position on the mounting bracket and install the
mounting screws.
6. Reconnect the harness connectors to the ignition coil. Confirm that the
harness connectors are firmly attached to the coil.
7. Install the secondary coil wire to the coil tower.
8. Connect the negative battery cable.