1982 CHEVROLET CAMARO check engine

GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 574
In the event of an ECM failure, the system
will default to a pre-programmed set
of values. These are compromise values which allow the engine to operate,
although possibly at reduced e fficiency. This is variously known as the default,
limp-in/limp-home or back-up mode. Driveability is almost always affected when
the ECM enters this mode.

Fig. 1: Computer Co mmand Control schematic

GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 576
The temporary nature
of the integrator's control is expanded by the block learn
function. The name is derived from the fact that the entire engine operating
range (load vs. rpm) is divided into sect ions or blocks. Within each memory
block is stored the correct fuel delivery value for that combination of load and
engine speed. Once the operating range enters a certain block, that stored
value controls the fuel delivery unless th e integrator steps in to change it. If
changes are made by the integrator, t he new value is memorized and stored
within the block. As the block learn makes the correction, the integrator
correction will be reduced until the integrator returns to 128; the block learn then
controls the fuel delivery with the new value.

Fig. 4: Inexpensive scan tools, such as this Auto Xray®, are available to
interface with your General Motors vehicle
The next time the engine operates within the block's range, the new value will
be used. The block learn data can also be read by a scan tool; the range is the
same as the integrator and should also center on 128. In this way, the systems
can compensate for engine wear, small air or vacuum leaks or reduced
combustion.
Any time the battery is disconnected, the block learn values are lost and must
be relearned by the ECM. This loss of corrected values may be noticed as a
significant change in driveab ility. To re-teach the system, make certain the
engine is fully warmed up. Drive the v ehicle at part throttle using moderate
acceleration and idle until normal performance is felt.

GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 577
MALFUNCTION INDICATOR LAMP
The primary function of the MIL is to adv
ise the operator and the technician that
a fault is detected, and, in most cases, a code is stored. Under normal
conditions, the malfunction indicator la mp will illuminate when the ignition is
turned ON. Once the engine is started and running, the ECM will perform a
system check and extinguish the lamp if no fault is found.
Additionally, the lamp can be used to retrieve stored codes after the system is
placed in the Diagnostic Mode. Codes ar e transmitted as a series of flashes
with short or long pauses. When the syst em is placed in the Field Service
Mode, the dash lamp will indicate open loop or closed loop function to the
technician.
INTERMITTENTS
If a fault occurs intermittently, such as a loose connector pin breaking contact
as the vehicle hits a bump, the ECM will note the fault as it occurs and energize
the dash warning lamp. If the problem se lf-corrects, as with the terminal pin
again making contact, the dash lamp will extinguish after 10 seconds but\
a code
will remain stored in the ECM memory.
When an unexpected code appe ars during diagnostics, it may have been set
during an intermittent failure that self-c orrected; the codes are still useful in
diagnosis and should not be discounted.
OXYGEN SENSOR
OPERATION
An oxygen sensor is used on all models. The sensor protrudes into the exhaust
stream and monitors the oxygen content of the exhaust gases. The difference
between the oxygen content of the exhaust gases and that of the outside air
generates a voltage si gnal to the ECM. The ECM monitors this voltage and,
depending upon the value of the signal rece ived, issues a command to adjust
for a rich or a lean condition.
No attempt should ever be made to meas ure the voltage output of the sensor.
The current drain of any conventional vo ltmeter would be such that it would
permanently damage the sensor.

GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 579

Fig. 2: The oxygen sensor can be locat ed on either the left, right or both
exhaust manifolds
REMOVAL & INSTALLATION
The sensor may be difficult to remove when the engine temperature is below
120°F (48°C). Excessive removal force may damage the threads in the exhaust
manifold or pipe; follow the removal procedure carefully.
1. Disconnect the negative battery cable.
2. Locate the oxygen sensor. It protr udes from the exhaust manifold (it
looks somewhat like a spark plug).
3. Disconnect the electrical wiring from the oxygen sensor harness.

GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 580
4. Spray a commercial solvent onto the sensor threads and allow it to soak
in for at least five minutes.
5. Carefully remove the sensor wit h a special oxygen sensor socket.
To install: 6. First coat the new sensor's th reads with GM anti-seize compound No.
5613695 or the equivalent. This is not a conventional anti-seize paste.
The use of a regular compound may el ectrically insulate the sensor,
rendering it inoperative. Y ou must coat the threads with an electrically
conductive anti-seize compound. Installati on torque is 30 ft. lbs. (41 Nm).
Do not overtighten.
7. Reconnect the electric al wiring. Be careful not to damage the electrical
pigtail. Check the sensor boot fo r proper fit and installation.
8. Reconnect the negative battery cable.
COOLANT TEMPERATURE SENSOR
OPERATION
Most engine functions are affected by the coolant temperature. Determining
whether the engine is hot or cold is largely dependent on the temperature of the
coolant. An accurate temperature signal to the ECM is supplied by the coolant
temperature sensor. The coolant temperatur e sensor is a thermistor mounted in
the engine coolant stream. A thermistor is an electrical device that varies its
resistance in relation to changes in temperature. Low coolant temperature
produces a high resistance and high coolant temperature produces low
resistance. The ECM supplies a signal of 5 volts to the coolant temperature
sensor through a resistor in the ECM and measures the voltage. The voltage
will be high when the engine is cold and low when the engine is hot.
REMOVAL & INSTALLATION
1. Disconnect the negative battery cable.
2. Drain the cooling system to an appropr iate and clean container for reuse.
3. Disconnect the electrical wiring fr om the coolant temperature sensor.
4. Remove the coolant temperature sensor.
To install: 5. Install the coolant temperature sensor.
6. Connect the electrical wiring.
7. Fill the cooling system.
8. Connect the negative battery cable.
9. Start the engine and check for leaks.

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) 582
REMOVAL & INSTALLATION
On some models it may be necessary
to remove the air inlet assembly.
1. Disconnect the negative battery cable. Disconnect the IAC valve
electrical wiring.
2. Remove the IAC valve by performing the following: a. On thread-mounted units, use a 1
1/4 inch (32mm) wrench.
b. On flange-mounted units, remove the mounting screw assemblies.
3. Remove the IAC valve ga sket or O-ring and discard.
To install: 4. Clean the mounting surfaces by performing the following:
a. If servicing a thread-mounted valve, remove the old gasket material from the surf ace of the throttle body to ensure proper
sealing of the new gasket.
b. If servicing a flange-mounted valve, clean the IAC valve surfaces on the throttle body to assure pr oper seal of the new O-ring and
contact of the IAC valve flange.
5. If installing a new IAC valve, meas ure the distance between the tip of the
IAC valve pintle and the mounting flange. If the distance is greater than
1.102 inch (28mm), use finger pressure to slowly retract the pintle. The
force required to retract the pintle of a new valve will not cause damage
to the valve. If reinstalling the origin al IAC valve, do not attempt to adjust
the pintle in this manner.
6. Install the IAC valve into the thro ttle body by performing the following:
a. With thread-mounted valves, in stall with a new gasket. Using a
1
1/4 inch (32mm) wrench, tighten to 13 ft. lbs. (18 Nm).
b. With flange-mounted valves, lubricate a new O-ring with
transmission fluid and install on the IAC valve. Install the IAC
valve to the throttle body. Inst all the mounting screws using a
suitable thread locking compound. Tight en to 28 inch lbs. (3 Nm).
7. Connect the IAC valve electrical wiring.
8. Connect the negative battery cable.
9. No physical adjustment of the IAC valve assembly is required after installation. Reset the IAC valve pintle position by performing the
following:
a. Depress the accelerator pedal slightly.
b. Start the engine and run for 5 seconds.
c. Turn the ignition switch to the OFF position for 10 seconds.
d. Restart the engine and check for proper idle operation.

GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 585
MANIFOLD ABSOLUTE PRESSURE SENSOR
OPERATION
The MAP sensor measures the changes in
intake manifold pressure, which
result from engine load/ speed changes and converts this information to a
voltage output. The MAP sensor reading is the opposite of a vacuum gauge
reading: when manifold pressu re is high, MAP sensor value is high and vacuum
is low. A MAP sensor will produce a low output on engine coast-down with a
closed throttle while a wide open throttle will produce a high output. The high
output is produced because the pressure inside the manifold is the same as
outside the manifold, so 100 percent of t he outside air pressure is measured.
The MAP sensor is also used to meas ure barometric pressure under certain
conditions, which allows the ECM to autom atically adjust for different altitudes.
The MAP sensor changes the 5 volt signal supplied by the ECM, which reads
the change and uses the information to cont rol fuel delivery and ignition timing.

Fig. 1: MAP sensor
REMOVAL & INSTALLATION 1. Disconnect the negative battery cable.
2. Disconnect the vacuum connection.
3. Release the electrical wiring lo cking tab and disconnect the connector.
4. Remove the bolts or release the MAP sensor locking tabs and remove
the sensor.
To install: 5. Install the bolts or snap sensor onto the bracket.