1B – 2 SOHC ENGINE MECANICAL
DAEWOO M-150 BL2
DESCRIPTION AND OPERATION
ENGINE TYPE
The engine is 4-cycle, water-cooled, in-line 3 cylinders
with displacement of 796cc (68.5×72.0mm) (2.70×
2.83 in.).
Engine model
(Specifications)F8C Type SOHC /
2 Valve (MPI)
Maximum power (kw/rpm)37.5 / 6,000
Maximum torque (Nm/rpm)68.6 / 4,600
Compression ratio9.3 : 1
D102B001
ENGINE LUBRICATION
The engine lubrication is of the wetsump method to draw
up the oil forced by the oil pump. The oil pump is of a
trochoid type, and mounted on crankshaft at crankshaft
pulley side (a). Oil is drawn up through oil pump pickup
tube (b) and passed through pump (c) to oil filter (d). The
filtered oil flows into two paths in engine block. In one
path (e), oil reaches crankshaft journal bearings. Oil
from crankshaft journal bearings is supplied to connect-
ing rod bearings by means of intersecting passages
drilled in crankshaft, and then injected from a small hole
provided on big end of connecting rod to lubricate piston
(f), rings, and cylinder wall. In another path (g), oil goes
up to cylinder head and lubricates rocker arm (i), valve
(j), camshaft (k), etc. through the oil hole provided on the
rocker arm shaft (h).
D102B002
CYLINDER HEAD AND VALVE TRAIN
The cylinder head is made of cast aluminum alloy for
better strength in hardness with lightweight, and cam-
shaft (k) and rocker arm shaft (h) arranged in-line sup-
port.
D102B003
The combustion chambers are formed into the manifold
combustion chambers with increased squish parts for
better combustion efficiency and its intake and exhaust
1D – 2 ENGINE COOLING
DAEWOO M-150 BL2
DESCRIPTION AND OPERATION
GENERAL DESCRIPTION
The cooling system maintains the engine temperature at
an efficient level during all engine operating conditions.
When the engine is cold the cooling system cools the
engine slowly or not at all. This slow cooling of the en-
gine allows the engine to warm up quickly.
The cooling system includes a radiator(a) and cooling
fan(b), a thermostat and housing(c), a coolant pump(d),
a coolant pump drive belt and coolant hose. The timing
belt drives the coolant pump.
All components must function properly in order for the
cooling system to operate. The coolant pump draws the
coolant from the radiator. The coolant then circulates
through water jackets in the engine block and the cylin-
der head, distributor case(e), throttle body(f). When the
coolant reaches the operating temperature of the ther-
mostat, the thermostat opens. The coolant then goes
back to the radiator where it cools.
This system directs some coolant through the hoses to
the heater core(g). This provides for heating and de-
frosting. The surge tank(h) is connected to the radiator
and throttle body to recover the coolant displaced by ex-
pansion from the high temperatures. The surge tank
maintains the correct coolant level.
The cooling system for this vehicle has no radiator cap
and drain cock. The coolant is added to the cooling sys-tem through the surge tank. To drain the cooling system,
disconnect the lower radiator hose and drain the cool-
ant.
RADIATOR
This vehicle has a lightweight tube-and-fin aluminum ra-
diator.
SURGE TANK
The surge tank is a transparent plastic reservoir, similar
to the windshield washer reservoir.
The surge tank is connected to the radiator and throttle
body by a hose. As the vehicle is driven, the engine cool-
ant heats and expands. The portion of the engine cool-
ant displaced by this expansion flows from the radiator
into the surge tank. The air trapped in the radiator is de-
gassed into the surge tank.
When the engine is stops, the engine coolant cools and
contracts. The displaced engine coolant is then drawn
back into the radiator. This keeps the radiator filled with
the coolant to the desired level at all times and increases
the cooling efficiency.
Maintain the coolant level between the MIN and the
MAX marks on the surge tank when the system is cold.
D102D001
1F–16 ENGINE CONTROLS
DAEWOO M-150 BL2
the obstruction of the reference air and degrade the O2S
performance.
Misfire Monitor Diagnostic Operation
The misfire monitor diagnostic is based on crankshaft
rotational velocity (reference period) variations. The En-
gine Control Module (ECM) determines crankshaft rota-
tional velocity using the Crankshaft Position (CKP)
sensor and the Camshaft Position (CMP) sensor. When
a cylinder misfires, the crankshaft slows down momen-
tarily. By monitoring the CKP and CMP sensor signals,
the ECM can calculate when a misfire occurs.
For a non-catalyst damaging misfire, the diagnostic will
be required to monitor a misfire present for between
1000–3200 engine revolutions.
For catalyst-damaging misfire, the diagnostic will re-
spond to misfire within 200 engine revolutions.
Rough roads may cause false misfire detection. A rough
road will cause torque to be applied to the drive wheels
and drive train. This torque can intermittently decrease
the crankshaft rotational velocity. This may be falsely
detected as a misfire.
A rough road sensor, or “G sensor,” works together with
the misfire detection system. The rough road sensor
produces a voltage that varies along with the intensity of
road vibrations. When the ECM detects a rough road,
the misfire detection system is temporarily disabled.
Misfire Counters
Whenever a cylinder misfires, the misfire diagnostic
counts the misfire and notes the crankshaft position at
the time the misfire occurred. These “misfire counters”
are basically a file on each engine cylinder. A current
and a history misfire counter are maintained for each
cylinder. The misfire current counters (Misfire Current
#1–4) indicate the number of firing events out of the last
200 cylinder firing events which were misfires. The mis-
fire current counter will display real time data without a
misfire DTC stored. The misfire history counters (Misfire
Histtory #1–4) indicate the total number of cylinder firing
events which were misfires. The misfire history counters
will display 0 until the misfire diagnostic has failed and a
DTC P0300 is set. Once the misfire DTC P0300 is set,
the misfire history counters will be updated every 200
cylinder firing events. A misfire counter is maintained for
each cylinder.
If the misfire diagnostic reports a failure, the diagnostic
executive reviews all of the misfire counters before re-
porting a DTC. This way, the diagnostic executive re-
ports the most current information.
When crankshaft rotation is erratic, a misfire condition
will be detected. Because of this erratic condition, the
data that is collected by the diagnostic can sometimes
incorrectly identify which cylinder is misfiring.
Use diagnostic equipment to monitor misfire counter
data on EOBD compliant vehicles. Knowing which spe-
cific cylinder(s) misfired can lead to the root cause, evenwhen dealing with a multiple cylinder misfire. Using the
information in the misfire counters, identify which cylin-
ders are misfiring. If the counters indicate cylinders
numbers 1 and 4 misfired, look for a circuit or compo-
nent common to both cylinders number 1 and 4.
The misfire diagnostic may indicate a fault due to a tem-
porary fault not necessarily caused by a vehicle emis-
sion system malfunction. Examples include the following
items:
Contaminated fuel.
Low fuel.
Fuel-fouled spark plugs.
Basic engine fault.
Fuel Trim System Monitor Diagnostic
Operation
This system monitors the averages of short-term and
long-term fuel trim values. If these fuel trim values stay
at their limits for a calibrated period of time, a malfunc-
tion is indicated. The fuel trim diagnostic compares the
averages of short-term fuel trim values and long-term
fuel trim values to rich and lean thresholds. If either val-
ue is within the thresholds, a pass is recorded. If both
values are outside their thresholds, a rich or lean DTC
will be recorded.
The fuel trim system diagnostic also conducts an intru-
sive test. This test determines if a rich condition is being
caused by excessive fuel vapor from the controlled char-
coal canister. In order to meet EOBD requirements, the
control module uses weighted fuel trim cells to deter-
mine the need to set a fuel trim DTC. A fuel trim DTC
can only be set if fuel trim counts in the weighted fuel
trim cells exceed specifications. This means that the ve-
hicle could have a fuel trim problem which is causing a
problem under certain conditions (i.e., engine idle high
due to a small vacuum leak or rough idle due to a large
vacuum leak) while it operates fine at other times. No
fuel trim DTC would set (although an engine idle speed
DTC or HO2S DTC may set). Use a scan tool to observe
fuel trim counts while the problem is occurring.
A fuel trim DTC may be triggered by a number of vehicle
faults. Make use of all information available (other DTCs
stored, rich or lean condition, etc.) when diagnosing a
fuel trim fault.
Fuel Trim Cell Diagnostic Weights
No fuel trim DTC will set regardless of the fuel trim
counts in cell 0 unless the fuel trim counts in the
weighted cells are also outside specifications. This
means that the vehicle could have a fuel trim problem
which is causing a problem under certain conditions (i.e.
engine idle high due to a small vacuum leak or rough
due to a large vacuum leak) while it operates fine at oth-
er times. No fuel trim DTC would set (although an en-
gine idle speed DTC or HO2S DTC may set). Use a
scan tool to observe fuel trim counts while the problem is
occurring.
ENGINE CONTROLS 1F–247
DAEWOO M-150 BL2
Excessive engine overloading. Check for seized pul-
leys, pumps, or motors on the accessory drive,Overweight engine oil.
DTC P0505 Idle Air Control Valve (IACV) Circuit Fault
StepActionValue(s)YesNo
1
Perform an On-Board Diagnostic (EOBD) System
Check.
Was the check performed?
–
Go to Step 2
Go to
“On-Board
Diagnostic
System Check”
2
1. Install a scan tool to the Data Link Connector
(DLC).
2. Operate the engine to idle speed.
3. Transmission in park or neutral and the parking
brake set.
4. A/C is off.
5. Using scan tool, command the Idle Air Control
(IAC) valve up and down between the specified
value.
Does the rpm change smoothly when he
commanded by the scan tool?
900–1200
rpm
Go to Step 3Go to Step 5
3
1. Turn the ignition OFF.
2. Disconnect the IAC valve connector.
3. Measure the resistance between terminal C and
D of the IAC valve.
4. Measure the resistance between terminal B and A
of the IAC valve.
Is the resistance within the specified value?
40–80 ΩGo to Step 4Go to Step 13
4
1. Measure the resistance between terminal D and
B of the IAC valve.
2. Measure the resistance between terminal C and
A of the IAC valve.
Is the resistance equal to the specified value?
∞Go to Step 15Go to Step 13
5
1. Turn the ignition OFF.
2. Disconnect the IAC valve connector.
3. Turn the ignition ON.
4. With test light connected to ground, probe the
IAC connector terminals.
Does the test light illuminate on D terminals?
–
Go to Step 6Go to Step 7
6
With test light connected to B+, probe the IAC
connector terminals.
Does the test light illuminate on D terminals?
–
Go to Step 8Go to Step 9
7
Check for an open or short to ground in the IAC high
and low circuits and repair as needed.
Is the repair complete?
–
Go to Step 15Go to Step 10
8
1. Idle the engine.
2. Connect a test light to ground, probe the IAC
connector terminals.
Does the test light flash On and OFF for all
terminals?
–
Go to Step 11Go to Step 12
9
Check for an open or a short to voltage in the IAC
valve high and low circuits and repair as needed.
Is the repair complete?
–
Go to Step 15Go to Step 10
10
Check the Engine control Module (ECM) connector
for poor connections and repair as needed.
Is the repair complete?
–
Go to Step 15Go to Step 14