Downloaded from www.Manualslib.com manuals search engine ENGINE GENERAL INFORMATION AND DIAGNOSIS 6-25
Excessive detonation
(The engine makes
sharp metallic knocks
that change with throt-
tle opening.
Sounds like pop corn
popping.)Engine overheating Refer to “Overheating” of this table.
Faulty spark plug Spark plugs in Section 6F.
Clogged fuel filter and fuel lines Diagnostic Flow Table B-3
Malfunctioning EGR valve (if equipped) EGR system in Section 6E.
Poor performance of knock sensor, ECT
sensor or MAP sensorKnock sensor in this section, ECT
sensor or MAP sensor in Section 6E.
Faulty injector Diagnostic Flow Table B-1
Faulty ECM Inspection of ECM and its circuit in
this section.
Excessive combustion chamber deposits Piston and cylinder head in Section
6A1.
Overheating
Inoperative thermostat Thermostat in Section 6B.
Faulty A/C condenser fan motor or its cir-
cuitA/C condenser fan control system
check in Section 6E.
Loose or slip water pump belt ITEM1-1 Drive belt inspection and
change in Section 0B.
Poor water pump performance Water pump in Section 6B.
Clogged or leaky radiator Radiator in Section 6B.
Improper engine oil grade ITEM1-3 Engine oil and oil filter
change in Section 0B.
Clogged oil filter or oil strainer Oil pressure check in Section 6A1.
Poor oil pump performance Oil pressure check in Section 6A1.
Dragging brakes Diagnosis Table in Section 5.
Slipping clutch Diagnosis Table in Section 7C.
Blown cylinder head gasket Valves and cylinder head in Section
6A1.
Poor gasoline mileage
Faulty ignition coil Ignition coil assembly in Section 6F.
Fuel pressure out of specification Diagnostic Flow Table B-3
Faulty TP sensor, ECT sensor or MAP
sensorTP sensor, ECT sensor or MAP sen-
sor in Section 6E.
Faulty injector Diagnostic Flow Table B-1
Faulty ECM Inspection of ECM and its circuit in
this section.
Malfunctioning EGR valve (if equipped) EGR system in Section 6E.
High idle speed Refer to item “Improper Engine Idle
Speed” previously outlined.
Low compression Previously outlined.
Poor valve seating Valves and cylinder head in Section
6A1.
Dragging brakes Diagnosis Table in Section 5.
Slipping clutch Diagnosis Table in Section 7C.
Thermostat out of order Thermostat in Section 6B.
Improper tire pressure Refer to Section 3F. Condition Possible Cause Reference Item
Downloaded from www.Manualslib.com manuals search engine 6-26 ENGINE GENERAL INFORMATION AND DIAGNOSIS
Excessive engine oil
consumptionSticky piston ring Pistons, piston rings, connecting rods
and cylinders in Section 6A1.
Worn piston and cylinder Pistons, piston rings, connecting rods
and cylinders in Section 6A1.
Worn piston ring groove and ring Pistons, piston rings, connecting rods
and cylinders in Section 6A1.
Improper location of piston ring gap Pistons, piston rings, connecting rods
and cylinders in Section 6A1.
Worn or damaged valve stem seal Valves and cylinder head in Section
6A1.
Worn valve stem Valves and cylinder head in Section
6A1.
Low oil pressure
Improper oil viscosity ITEM1-3 Engine oil and oil filter
change in Section 0B.
Malfunctioning oil pressure switch Oil pressure switch in Section 8.
Clogged oil strainer Oil pan and oil pump strainer in Sec-
tion 6A1.
Functional deterioration of oil pump Oil pump in Section 6A1.
Worn oil pump relief valve Oil pump in Section 6A1.
Excessive clearance in various sliding
partsRefer to Section 6A1.
Engine noise
See NOTE below.Improper valve lash Valve lash in Section 6A1.
Worn valve stem and guide Valves and cylinder head in Section
6A1.
Weak or broken valve spring Valve springs in Section 6A1.
Warped or bent valve Valves and cylinder head in Section
6A1.
Loose camshaft housing bolts Camshaft in Section 6A1.
Worn piston, ring and cylinder bore Pistons and cylinders in Section 6A1.
Worn crankpin bearing Crankpin and connecting rod bearing
in Section 6A1.
Worn crankpin Crankpin and connecting rod bearing
in Section 6A1.
Loose connecting rod nuts Connecting rod in Section 6A1.
Low oil pressure Previously outlined.
Worn crankshaft journal bearing Main bearings, Crankshaft and cylin-
der block in Section 6A1.
Worn crankshaft journal Main bearings, Crankshaft and cylin-
der block in Section 6A1.
Loose lower crankcase (bearing cap) bolts Main bearings, Crankshaft and cylin-
der block in Section 6A1.
Excessive crankshaft thrust play Main bearings, Crankshaft and cylin-
der block in Section 6A1. Condition Possible Cause Reference Item
NOTE:
Before checking the mechanical noise, make sure that :
Ignition timing is properly adjusted.
Specified spark plug is used.
Specified fuel is used.
Downloaded from www.Manualslib.com manuals search engine ENGINE GENERAL INFORMATION AND DIAGNOSIS 6-27
Condition Possible Cause Reference Item
Excessive hydrocar-
bon (HC) emission or
Excessive carbon mon-
oxide (CO) emissionFaulty ignition coil Ignition coil assembly in Section 6F.
Fuel pressure out of specification Diagnostic Flow Table B-3
Lead contamination of three way catalytic
converterMaintenance in Section 6K.
Malfunctioning PCV system PCV system in Section 6E.
Faulty EVAP control system EVAP control system in Section 6E.
Closed loop system (A/F feed back com-
pensation) fails
–Faulty TP sensor
–Faulty ECT sensor or MAP sensor
–Faulty oxygen sensorCheck oxygen sensor output voltage.
Refer to DTC P0130 (No.14) Table in
this section.
Faulty injector Diagnostic Flow Table B-1
Faulty ECM Inspection of ECM and its circuit in
this section.
Low compression Previously outlined.
Excessive nitrogen
oxides (NOx) emissionFuel pressure out of specification Diagnostic Flow Table B-3
Lead contamination of three way catalytic
converterMaintenance in Section 6K.
Closed loop system (A/F feed back com-
pensation) fails
–Faulty TP sensor
–Faulty ECT sensor or MAP sensor
–Faulty oxygen sensorCheck oxygen sensor output voltage
Refer to DTC P0130 (No.14) Table in
this section.
Faulty injector Diagnostic Flow Table B-1
Faulty ECM Inspection of ECM and its circuit in
this section.
Faulty EGR system (if equipped) EGR system in Section 6E.
Downloaded from www.Manualslib.com manuals search engine ENGINE GENERAL INFORMATION AND DIAGNOSIS 6-33
Inspection of ECM and Its Circuits
ECM and its circuits can be checked at ECM wiring connectors by
measuring voltage and resistance.
VOLTAGE CHECK
1) Remove ECM from body referring to Section 6E.
2) Check voltage at each terminal of connectors connected.CAUTION:
ECM cannot be checked by itself. It is strictly prohibited
to connect voltmeter or ohmmeter to ECM with connector
disconnected from it.
NOTE:
As each terminal voltage is affected by the battery volt-
age, confirm that it is 11 V or more when ignition switch
is ON.
1. ECM
2. ECM connectors (Viewed from harness side)
Downloaded from www.Manualslib.com manuals search engine 6-48 ENGINE GENERAL INFORMATION AND DIAGNOSIS
DTC P0105 (DTC No.11) Manifold Absolute Pressure (MAP) Circuit Malfunc-
tion
CIRCUIT DESCRIPTION
DTC CONFIRMATION PROCEDURE
1) Clear DTC, start engine and keep it at idle for 1 min.
2) Select “DTC” mode on scan tool and check DTC.
INSPECTION
DTC DETECTING CONDITION POSSIBLE CAUSE
MAP sensor signal is 0.19 V or lower.
(Low pressure – High vacuums – Low voltage)
MAP sensor signal is 4.5 V or higher.
(High pressure – Low vacuums – High voltage)“B/Bl” circuit open
“Lg/R” circuit open or shorted to ground
“G” circuit open or shorted to ground
MAP sensor malfunction
ECM malfunction
NOTE:
When DTC P0120 is indicated together, it is possible that “Lg/R” circuit is open.
When DTC P0105 (No.11), P0110 (No.18) P0115 (No.19) P0120 (No.13) and P0460 are indicated
together, it is possible that “B/Bl” circuit is open.
Step Action Yes No
1Was “Engine Diag. Flow Table” performed? Go to Step 2. Go to “Engine Diag. Flow
Table”.
2 Check MAP Sensor and Its Circuit.
1) Connect scan tool to DLC with ignition
switch OFF. See Fig. 1.
2) Turn ignition switch ON.
3) Check intake manifold pressure.
Is it 126 kPa (37.2 inHg) or 0 kPa (0 inHg)?Go to Step 3. Intermittent trouble.
Check for intermittent
referring to “Intermittent
and Poor Connection” in
Section 0A.
Downloaded from www.Manualslib.com manuals search engine ENGINE GENERAL INFORMATION AND DIAGNOSIS 6-51
DTC P0110 (DTC No.18) Intake Air Temp. (IAT) Circuit Malfunction
CIRCUIT DESCRIPTION
DTC CONFIRMATION PROCEDURE
1) Clear DTC, start engine and keep it at idle for 1 min.
2) Select “DTC” mode no scan tool and check DTC.
INSPECTION
DTC DETECTING CONDITION POSSIBLE CAUSE
Low intake air temperature (High voltage-High resistance)
High intake air temperature (Low voltage-Low resistance)“Lg/R” circuit open or shorted to power.
“B/Bl” circuit open
IAT sensor malfunction
ECM malfunction
NOTE:
When DTC P0105 (No.11), P0110 (No.18), P046, P0115 (No.19) and P0120 (No.13) are indicated
together, it is possible that “B/Bl” circuit is open.
Before inspecting, be sure to check that ambient temperature is higher than –40 °C (–40 °F).
Step Action Yes No
1Was “Engine Diag. Flow Table” performed? Go to Step 2. Go to “Engine Diag. Flow
Table”.
2 Check IAT Sensor and Its Circuit.
1) Connect scan tool to DLC with ignition
switch OFF. See Fig. 1.
2) Turn ignition switch ON.
3) Check intake air temp. displayed on scan
tool.
Is –40 °C (–40 °F) or 119 °C (246 °F) indicated?Go to Step 3. Intermittent trouble.
Check for intermittent
referring to “Intermittent
and Poor Connection” in
Section 0A.
Downloaded from www.Manualslib.com manuals search engine 6-54 ENGINE GENERAL INFORMATION AND DIAGNOSIS
INSPECTION
[A] Fig. 1 for Step 2 / [B] Fig. 2 for Step 5 / [C] Fig. 3 for Step 6Step Action Yes No
1Was “Engine Diag. Flow Table” performed? Go to Step 2. Go to “Engine Diag. Flow
Table”.
2 Check ECT Sensor and Its Circuit.
1) Connect scan tool with ignition switch OFF.
See Fig. 1.
2) Turn ignition switch ON.
3) Check engine coolant temp. displayed on
scan tool.
Is –40 °C (–40 °F) or 119 °C (246 °F) indicated?Go to Step 3. Intermittent trouble.
Check for intermittent
referring to “Intermittent
and Poor Connection” in
Section 0A.
3 Check Wire Harness.
1) Disconnect ECT sensor connector.
2) Check engine coolant temp. displayed on
scan tool.
Is –40 °C (–40 °F) indicated?Replace ECT sensor.“G/B” wire shorted to
ground.
If wire is OK, substitute a
known-good ECM and
recheck.
4 Does scan tool indicate –40 °C (–40 °F) at Step
2.Go to Step 6. Go to Step 5.
5 Check Wire Harness.
1) Disconnect ECT sensor connector with igni-
tion switch OFF.
2) Check for proper connection to ECT sensor
at “B/Bl” and “G/B” wire terminals.
See Fig. 2.
3) If OK, then with ignition switch ON.
Is voltage applied to “B/Bl” wire terminal about
4 – 6 V?Go to Step 4.“G/B” wire open or
shorted to power, or poor
E19-14 connection.
If wire and connection are
OK, substitute a known-
good ECM and recheck.
6 Check Wire Harness.
1) Using service wire, connect ECT sensor
connector terminals. See Fig. 3.
2) Turn ignition switch ON and check engine
coolant temp. displayed on scan tool.
Is 119 °C (246 °F) indicated?Replace ECT sensor.“B/Bl” wire open or poor
E19-10 connection.
If wire and connection are
OK, substitute a known-
good ECM and recheck.
Downloaded from www.Manualslib.com manuals search engine 6-56 ENGINE GENERAL INFORMATION AND DIAGNOSIS
INSPECTION
[A] Fig. 1 for Step 2 / [B] Fig. 2 for Step 3 / [C] Fig. 3 for Step 4Step Action Yes No
1Was “Engine Diag. Flow Table” performed? Go to Step 2. Go to “Engine Diag. Flow
Table”.
2 Check TP Sensor and Its Circuit.
1) Connect scan tool to DLC with ignition
switch OFF and then turn ignition switch ON.
See Fig. 1.
2) Check throttle valve opening percentage dis-
played on scan tool.
Is it displayed 0% or 100%?Go to Step 3. Intermittent trouble.
Check for intermittent
referring to “Intermittent
and Poor Connection” in
Section 0A.
3 Check Wire Harness.
1) Disconnect connector from TP sensor with
ignition switch OFF.
2) Check for proper connection to TP sensor at
“Lg/R”, “Lg” and “B/Bl” wire terminal.
3) If OK, then with ignition switch ON, check
voltage at each of “Lg/R” and “Lg” wire ter-
minals and body ground. See Fig. 2.
Is voltage about 4 – 6 V at each terminal?Go to Step 4.“Lg/R” wire open, “Lg/R”
wire shorted to ground cir-
cuit or power circuit or
“B/Bl” wire, “Lg” wire open
or shorted to ground cir-
cuit or poor E19-22 or
E19-16 connection.
If wire and connection are
OK, substitute a known-
good ECM and recheck.
4 Check TP Sensor.
1) Check resistance between terminals of TP
sensor. See Fig. 3.
TP sensor resistance
Between 1 and 3 : 4.0 – 6.0 k
Ω
ΩΩ Ω
Between 2 and 3 : Varying according to
throttle valve opening (0.02 – 6.0 k
Ω
ΩΩ Ω)
Are measured values within specifications?“B/Bl” wire open or poor
E19-10 connection.
If wire and connection are
OK, substitute a known-
good ECM and recheck.Replace TP sensor.