1F–42 ENGINE CONTROLS
DAEWOO M-150 BL2
MAA1F070
IDLE AIR CONTROL SYSTEM CHECK
Circuit Description
The Engine Control Module (ECM) controls the engine
idle speed with the Idle Air Control (IAC) valve. To in-
crease the idle speed, the ECM pulls the IAC pintle
away from its seat, allowing more air to pass by the
throttle body. To decrease the idle speed, it extends the
IAC valve pintle toward its seat, reducing bypass air
flow. A scan tool will read the ECM commands to the
IAC valve in counts. The higher counts indicate more air
bypass (higher idle). The lower counts indicate less air is
allowed to bypass (lower idle).
Diagnostic Aids
If the idle is too high, stop the engine. Fully extend the
Idle Air Control (IAC) valve with a IAC driver. Start the
engine. If the idle speed is above 950 rpm, locate and
repair the vacuum leak. Also, check for a binding throttle
plate or throttle linkage or an incorrect base idle setting.
Idle Air Control Valve Reset Procedure
Whenever the battery cable or the Engine Control Mod-
ule (ECM) connector or the ECM fuse EF6 is discon-nected or replaced, the following idle learn procedure
must be performed:
1. Turn the ignition ON for 5 seconds.
2. Turn the ignition OFF for 10 seconds.
3. Turn the ignition ON for 5 seconds.
4. Start the engine in park/neutral.
5. Allow the engine to run until the engine coolant is
above 85C (185F ).
6. Turn the A/C ON for 10 seconds, if equipped.
7. Turn the A/C OFF for 10 seconds, if equipped.
8. If the vehicle is equipped with an automatic trans-
axle, apply the parking brake. While pressing the
brake pedal, place the transaxle in D (drive).
9. Turn the A/C ON for 10 seconds, if equipped.
10. Turn the A/C OFF for 10 seconds, if equipped.
11. Turn the ignition OFF. The idle learn procedure is
complete.
1F–246 ENGINE CONTROLS
DAEWOO M-150 BL2
MAA1F070
DIAGNOSTIC TROUBLE CODE (DTC) 0505
IDLE AIR CONTROL VALVE (IACV) CIRCUIT FAULT
Circuit Description
The Engine Control Module (ECM) controls the air en-
tering into the engine with an Idle Air Control (IAC)
Valve. To increase the idle rpm, the ECM commands the
pintle inside the IAC valve away from the throttle body
seat. This allows more air to bypass through the throttle
blade. To decrease the rpm the ECM commands the
pintle towards the throttle body seat. This reduces the
amount of air bypassing the throttle blade. A scan tool
will read the IAC valve pintle position in counts. The
higher the counts, the more air that is allowed to bypass
the throttle blade. This Diagnostic Trouble Code (DTC)
determines if a low idle condition exists as defined as
100 rpm below the desired idle rpm.
Conditions for Setting the DTC
No intrusive tests are active.
DTC(s) P0106, P0107, P0108, P0112, P0113,
P0117, P0118, P0122, P0123, P0131, P0132,
P0133, P1133, P1134, P0171, P1171, P0172, P0201,
P0202, P0203, P0204, P0300, P0336, P0337,
P0341, P0342, P0351, P0352, P0402, P0404,
P1404, P0405, P0406, P0443, and P0502 are not
set.
Engine is running more than 60 seconds.
Barometric Pressure (BARO) is greater than 72 kPa
(10.4 psi).
Engine Coolant Temperature (ECT) is greater than
60C (140F).
Ignition voltage is between 11 and 16 volts.
The Intake Air Temperature (IAT) is greater than
–20C (–4F).
Manifold Absolute Pressure is less than 60 kPa (8.7
psi).IAC valve is controlled fully opened.
All of the above must be met for greater than 5 sec-
onds.
Action Taken When the DTC Sets
The Malfunction Indicator Lamp (MIL) will illuminate.
The ECM will record operating conditions at the time
the diagnostic fails. This information will be stored in
the Freeze Frame and Failure Records buffers.
A history DTC is stored.
Conditions for Clearing the MIL/DTC
The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
A history DTC will clear after 40 consecutive warm-up
cycles without a fault.
DTC(s) can be cleared by using the scan tool.
Disconnecting the ECM battery feed for more than 10
seconds.
Diagnostic Aids
Inspect the IAC valve electrical connection for proper
mating.
Inspect the wiring harness for damage.
Inspect the throttle stop screw for signs of tampering.
Inspect the throttle linkage for signs of binding or exces-
sive wear.
A slow or unstable idle may be caused by one of the fol-
lowing conditions:
Fuel system too rich or too lean.
Foreign material in the throttle body bore or in the air
induction system.
A leaking or restricted intake manifold.
1F–292 ENGINE CONTROLS
DAEWOO M-150 BL2
HESITATION, SAG, STUMBLE
Definition: Momentary lack of response as the accelera-
tor is pushed down. This can occur at any vehicle speed.
It is usually the most severe when first trying to make the
vehicle move, as from a stop. Hesitation, sag, or
stumble may cause the engine to stall if severe enough.Important: Before diagnosing this condition, check ser-
vice bulletins for PROM updates.
StepActionValue(s)YesNo
1
Were the Important Preliminary Checks performed?
–
Go to Step 2
Go to
“Important
Preliminary
Checks”
2
1. Check the fuel system pressure. If the pressure is
not within the value specified, service the fuel
system as needed.
2. Inspect the Throttle Position (TP) sensor for
binding or sticking. The TP sensor voltage should
increase at a steady rate as the throttle is moved
toward Wide Open Throttle (WOT).
Is the problem found?
380 kPa
(55 psi)
Go to Step 3Go to Step 4
3Repair or replace any components as needed.
Is the repair complete?–System OK–
4
1. Check the Manifold Absolute Pressure (MAP)
sensor response and accuracy.
2. Inspect the fuel for water contamination.
3. Check the Evaporative Emission (EVAP) Canister
Purge System for proper operation.
Is the problem found?
–
Go to Step 5Go to Step 6
5Repair or replace any components as needed.
Is the repair complete?–System OK–
6
1. Disconnect all of the fuel injector harness
connectors.
2. Connect an injector test light between the
harness terminals of each fuel injector.
3. Note the test light while cranking the engine.
Does the test light blink on all connectors?
–
Go to Step 8Go to Step 7
7
1. Repair or replace the faulty fuel injector drive
harness, the connector, or the connector terminal.
2. If the connections and the harnesses are good,
replace the Engine Control Module (ECM).
Is the repair complete?
–
System OK
–
8
Measure the resistance of each fuel injector.
Is the fuel injector resistance within the value
specified (the resistance will increase slightly at
higher temperatures)?
11.6–12.4 ΩGo to Step 10Go to Step 9
9
Replace any of the fuel injectors with a resistance
that is out of specifications.
Is the repair complete?
–
System OK
–
10Perform an injector diagnosis.
Is the problem found?–Go to Step 11Go to Step 12
11Replace any restricted or leaking fuel injectors.
Is the repair complete?–System OK–
12
Check the fuel system pressure after a cold start or
during moderate or full throttle acceleration.
Is the fuel pressure within specifications?
380 kPa
(55 psi)
Go to Step 14Go to Step 13
2B – 2 WHEEL ALIGNMENT
DAEWOO M-150 BL2
DESCRIPTION AND OPERATION
FOUR WHEEL ALIGNMENT
The first responsibility of engineering is to design safe
steering and suspension systems. Each component
must be strong enough to withstand and absorb extreme
punishment. Both the steering system and the front and
the rear suspension must function geometrically with the
body mass.
The steering and the suspension systems require that
the front wheels self-return and that the tire rolling effort
and the road friction be held to a negligible force in order
to allow the customer to direct the vehicle with the least
effort and the most comfort.
A complete wheel alignment check should include mea-
surements of the rear toe and camber.
Four-wheel alignment assures that all four wheels will be
running in precisely the same direction.
When the vehicle is geometrically aligned, fuel economy
and tire life are at their peak, and steering and perfor-
mance are maximized.
TOE
D16A006A
Toe–in is the turning in of the tires, while toe–out is the
turning out of the tires from the geometric centerline or
thrust line. The toe ensures parallel rolling of the wheels.
The toe serves to offset the small deflections of the
wheel support system which occur when the vehicle is
rolling forward. The specified toe angle is the setting
which achieves–degrees (0) of toe when the vehicle is
moving.
Incorrect toe-in or toe-out will cause tire wear and re-
duced fuel economy. As the individual steering and sus-
pension components wear from vehicle mileage,
additional toe will be needed to compensate for the
wear.
Always correct the toe dimension last.
CASTER
D16A008A
Caster is the tilting of the uppermost point of the steering
axis either forward or backward from the vertical when
viewed from the side of the vehicle. A backward tilt is
positive, and a forward tilt is negative. Caster influences
directional control of the steering but does not affect tire
wear. Weak springs or overloading a vehicle will affect
caster. One wheel with more positive caster will pull to-
ward the center of the car. This condition will cause the
car to move or lean toward the side with the least
amount of positive caster. Caster is measured in de-
grees and is not adjustable.
CAMBER
D16A007A
Camber is the tilting of the top of the tire from the vertical
when viewed from the front of the vehicle. When the
tires tilt outward, the camber is positive. When the tires
tilt inward, the camber is negative. The camber angle is
measured in degrees from the vertical. Camber in-
fluences both directional control and tire wear.
If the vehicle has too much positive camber, the outside
shoulder of the tire will wear. If the vehicle has too much
negative camber, the inside shoulder of the tire will wear.
Camber is measured in degrees and is not adjustable.