Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-45
Engine Symptom DiagnosisS6RW0D1104010
Perform troubleshooting referring to the followings when ECM has detected no DTC and no abnormality has been
found in “Visual Inspection” and “Engine Basic Inspection”.
Condition Possible cause Correction / Reference Item
Hard starting (Engine
cranks OK)Faulty spark plug“Spark Plug Inspection in Section 1H”
Leaky high-tension cord“High-Tension Cord Inspection in Section 1H”
Loose connection or disconnection of
high-tension cord(s) or lead wire(s)“High-Tension Cord Removal and Installation
in Section 1H”
Faulty ignition coil“Ignition Coil Assembly (Including Ignitor)
Inspection in Section 1H”
Dirty or clogged fuel hose or pipe“Fuel Pressure Check”
Malfunctioning fuel pump“Fuel Pressure Check”
Air drawn in through intake manifold
gasket or throttle body gasket
Faulty electric throttle body assembly“Electric Throttle Body Assembly On-Vehicle
Inspection in Section 1C”
Faulty APP sensor assembly“Accelerator Pedal Position (APP) Sensor
Assembly Inspection in Section 1C”
Faulty ECT sensor or MAF sensor“Engine Coolant Temperature (ECT) Sensor
Inspection in Section 1C” or “Intake Air
Temperature (IAT) Sensor Inspection in
Section 1C”
Faulty ECM
Low compression“Compression Check in Section 1D”
Poor spark plug tightening or faulty
gasket“Spark Plug Removal and Installation in
Section 1H”
Compression leak from valve seat“Valves and Valve Guides Inspection in
Section 1D”
Sticky valve stem“Valves and Valve Guides Inspection in
Section 1D”
Weak or damaged valve springs“Valve Spring Inspection in Section 1D”
Compression leak at cylinder head
gasket“Cylinder Head Inspection in Section 1D”
Sticking or damaged piston ring“Cylinders, Pistons and Piston Rings
Inspection in Section 1D”
Worn piston, ring or cylinder“Cylinders, Pistons and Piston Rings
Inspection in Section 1D”
Malfunctioning PCV valve“PCV Valve Inspection in Section 1B”
Camshaft position control (VVT) system
out of order (for engine with VVT
system)“Oil Control Valve Inspection (For Engine with
VVT) in Section 1D”
Faulty EGR system“EGR System Inspection (If Equipped) in
Section 1B”
Low oil pressureImproper oil viscosity“Engine Oil and Filter Change in Section 0B”
Malfunctioning oil pressure switch“Oil Pressure Switch Inspection in Section 9C”
Clogged oil strainer“Oil Pan and Oil Pump Strainer Cleaning in
Section 1E”
Functional deterioration of oil pump“Oil Pump Inspection in Section 1E”
Worn oil pump relief valve“Oil Pump Inspection in Section 1E”
Excessive clearance in various sliding
parts
Downloaded from www.Manualslib.com manuals search engine 1A-46 Engine General Information and Diagnosis:
Engine noise – Valve
noise
NOTE
Before checking
mechanical noise, make
sure that:
• Specified spark plug is
used.
• Specified fuel is used.
Improper valve lash“Camshaft, Tappet and Shim Inspection in
Section 1D”
Worn valve stem and guide“Valves and Valve Guides Inspection in
Section 1D”
Weak or broken valve spring“Valve Spring Inspection in Section 1D”
Warped or bent valve“Valves and Valve Guides Inspection in
Section 1D”
Engine noise – Piston,
ring and cylinder noise
NOTE
Before checking
mechanical noise, make
sure that:
• Specified spark plug is
used.
• Specified fuel is used.
Worn piston, ring and cylinder bore“Cylinders, Pistons and Piston Rings
Inspection in Section 1D”
Engine noise –
Connecting rod noise
NOTE
Before checking
mechanical noise, make
sure that:
• Specified spark plug is
used.
• Specified fuel is used.
Worn piston, ring and cylinder bore“Cylinders, Pistons and Piston Rings
Inspection in Section 1D”
Worn rod bearing“Crank Pin and Connecting Rod Bearings
Inspection in Section 1D”
Worn crank pin“Crank Pin and Connecting Rod Bearings
Inspection in Section 1D”
Loose connecting rod nuts“Pistons, Piston Rings, Connecting Rods and
Cylinders Removal and Installation in Section
1D”
Low oil pressureCondition “Low oil pressure”
Engine noise –
Crankshaft noise
NOTE
Before checking
mechanical noise, make
sure that:
• Specified spark plug is
used.
• Specified fuel is used.
Low oil pressureCondition “Low oil pressure”
Worn bearing“Main Bearings Inspection in Section 1D”
Worn crankshaft journal“Crankshaft Inspection in Section 1D”
Loose bearing cap bolts“Main Bearings, Crankshaft and Cylinder Block
Removal and Installation in Section 1D”
Excessive crankshaft thrust play“Crankshaft Inspection in Section 1D” Condition Possible cause Correction / Reference Item
Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-47
Engine overheatingInoperative thermostat“Thermostat Inspection in Section 1F”
Poor water pump performance“Water Pump Inspection in Section 1F”
Clogged or leaky radiator“Radiator On-Vehicle Inspection and Cleaning
in Section 1F”
Improper engine oil grade“Engine Oil and Filter Change in Section 0B”
Clogged oil filter or oil strainer“Oil Pressure Check in Section 1E”
Poor oil pump performance“Oil Pressure Check in Section 1E”
Faulty radiator cooling fan control
system“Radiator Cooling Fan Control System Check”
Dragging brakesCondition “Dragging brakes” in “Brakes
Symptom Diagnosis in Section 4A”
Slipping clutch (for M/T model)Condition “Slipping clutch” in “Clutch System
Symptom Diagnosis in Section 5C” for M/T
model
Blown cylinder head gasket“Cylinder Head Inspection in Section 1D”
Air mixed in cooling system
Poor gasoline mileageLeaks or loose connection of high-
tension cord“High-Tension Cord Removal and Installation
in Section 1H”
Faulty spark plug (improper gap, heavy
deposits and burned electrodes, etc.)“Spark Plug Inspection in Section 1H”
Malfunctioning EGR valve“EGR Valve Inspection (If Equipped) in Section
1B”
High idle speedCondition “Improper engine idling or engine
fails to idle”
Poor performance of ECT sensor, MAF
sensor“Engine Coolant Temperature (ECT) Sensor
Inspection in Section 1C”, or “Intake Air
Temperature (IAT) Sensor Inspection in
Section 1C”
Faulty electric throttle body assembly“Electric Throttle Body Assembly On-Vehicle
Inspection in Section 1C”
Faulty APP sensor assembly“Accelerator Pedal Position (APP) Sensor
Assembly Inspection in Section 1C”
Faulty fuel injector(s)“Fuel Injector Circuit Check”
Faulty ECM
Low compression“Compression Check in Section 1D”
Poor valve seating“Valves and Valve Guides Inspection in
Section 1D”
Dragging brakesCondition “Dragging brakes” in “Brakes
Symptom Diagnosis in Section 4A”
Slipping clutch (for M/T model)Condition “Slipping clutch” in “Clutch System
Symptom Diagnosis in Section 5C” for M/T
model
Thermostat out of order“Thermostat Inspection in Section 1F”
Improper tire pressure“Tires Description in Section 2D”
Camshaft position control (VVT) system
out of order (for engine with VVT
system)“Oil Control Valve Inspection (For Engine with
VVT) in Section 1D”
Excessive engine oil
consumption – Oil
leakageBlown cylinder head gasket“Cylinder Head Inspection in Section 1D”
Leaky camshaft oil seals“Camshaft, Tappet and Shim Inspection in
Section 1D” Condition Possible cause Correction / Reference Item
Downloaded from www.Manualslib.com manuals search engine 1A-48 Engine General Information and Diagnosis:
Excessive engine oil
consumption – Oil
entering combustion
chamberSticky piston ring“Cylinders, Pistons and Piston Rings
Inspection in Section 1D”
Worn piston and cylinder“Cylinders, Pistons and Piston Rings
Inspection in Section 1D”
Worn piston ring groove and ring“Cylinders, Pistons and Piston Rings
Inspection in Section 1D”
Improper location of piston ring gap“Pistons, Piston Rings, Connecting Rods and
Cylinders Disassembly and Assembly in
Section 1D”
Worn or damaged valve stem seal“Valves and Valve Guides Inspection in
Section 1D”
Worn valve stem“Valves and Valve Guides Inspection in
Section 1D”
Engine hesitates –
Momentary lack of
response as accelerator
is depressed. Can occur
at all vehicle speeds.
Usually most severe when
first trying to make
vehicle move, as from a
stop sign.Spark plug faulty or plug gap out of
adjustment“Spark Plug Inspection in Section 1H”
Leaky high-tension cord“High-Tension Cord Inspection in Section 1H”
Fuel pressure out of specification“Fuel Pressure Check”
Malfunctioning EGR valve“EGR Valve Inspection (If Equipped) in Section
1B”
Poor performance of ECT sensor or
MAF sensor, “Engine Coolant Temperature (ECT) Sensor
Inspection in Section 1C” or “Intake Air
Temperature (IAT) Sensor Inspection in
Section 1C”
Faulty electric throttle body assembly“Electric Throttle Body Assembly On-Vehicle
Inspection in Section 1C”
Faulty APP sensor assembly“Accelerator Pedal Position (APP) Sensor
Assembly Inspection in Section 1C”
Faulty fuel injector“Fuel Injector Circuit Check”
Faulty ECM
Engine overheatingCondition “Engine overheating”
Low compression“Compression Check in Section 1D”
Camshaft position control (VVT) system
out of order (for engine with VVT
system)“Oil Control Valve Inspection (For Engine with
VVT) in Section 1D”
Surge – Engine power
variation under steady
throttle or cruise. Feels
like vehicle speeds up
and down with no change
in accelerator pedal.Leaky or loosely connected high-tension
cord“High-Tension Cord Removal and Installation
in Section 1H”
Faulty spark plug (excess carbon
deposits, improper gap, burned
electrodes, etc.)“Spark Plug Inspection in Section 1H”
Variable fuel pressure“Fuel Pressure Check”
Kinky or damaged fuel hose and lines
Faulty fuel pump (clogged fuel filter)
Malfunctioning EGR valve“EGR Valve Inspection (If Equipped) in Section
1B”
Poor performance of MAF sensor“Intake Air Temperature (IAT) Sensor
Inspection in Section 1C”
Faulty fuel injector“Fuel Injector Circuit Check”
Faulty ECM
Faulty electric throttle body assembly“Electric Throttle Body Assembly On-Vehicle
Inspection in Section 1C”
Faulty APP sensor assembly“Accelerator Pedal Position (APP) Sensor
Assembly Inspection in Section 1C” Condition Possible cause Correction / Reference Item
Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-49
Excessive detonation –
Engine makes
continuously sharp
metallic knocks that
change with throttle
opening. Sounds like pop
corn popping.Faulty spark plug“Spark Plug Inspection in Section 1H”
Loose connection of high-tension cord“High-Tension Cord Removal and Installation
in Section 1H”
Engine overheatingCondition “Engine overheating”
Clogged fuel filter (faulty fuel pump) or
fuel lines“Fuel Pressure Check” or “Fuel Pump and Its
Circuit Check”
Air drawn in through intake manifold or
throttle body gasket
Malfunctioning EGR valve“EGR Valve Inspection (If Equipped) in Section
1B”
Poor performance of knock sensor, ECT
sensor or MAF sensor“DTC P0327 / P0328: Knock Sensor Circuit
Low / High”, “Engine Coolant Temperature
(ECT) Sensor Inspection in Section 1C” or
“Intake Air Temperature (IAT) Sensor
Inspection in Section 1C”
Faulty fuel injector(s)“Fuel Injector Circuit Check”
Faulty ECM
Excessive combustion chamber
deposits“Cylinders, Pistons and Piston Rings
Inspection in Section 1D” and/or “Piston Pins
and Connecting Rods Inspection in Section
1D”
Camshaft position control (VVT) system
out of order (for engine with VVT
system)“Oil Control Valve Inspection (For Engine with
VVT) in Section 1D”
Engine has no powerFaulty spark plug“Spark Plug Inspection in Section 1H”
Faulty ignition coil with ignitor“Ignition Coil Assembly (Including Ignitor)
Inspection in Section 1H”
Leaks, loose connection or
disconnection of high-tension cord“High-Tension Cord Removal and Installation
in Section 1H”
Faulty knock sensor“DTC P0327 / P0328: Knock Sensor Circuit
Low / High”
Clogged fuel hose or pipe“Fuel Pressure Check”
Malfunctioning fuel pump“Fuel Pump and Its Circuit Check”
Air drawn in through intake manifold
gasket or throttle body gasket
Engine overheatingCondition “Engine overheating”
Malfunctioning EGR valve“EGR Valve Inspection (If Equipped) in Section
1B”
Poor performance of ECT sensor or
MAF sensor“Engine Coolant Temperature (ECT) Sensor
Inspection in Section 1C” or “Intake Air
Temperature (IAT) Sensor Inspection in
Section 1C”
Faulty electric throttle body assembly“Electric Throttle Body Assembly On-Vehicle
Inspection in Section 1C”
Faulty APP sensor assembly“Accelerator Pedal Position (APP) Sensor
Assembly Inspection in Section 1C”
Faulty fuel injector(s)“Fuel Injector Circuit Check”
Faulty ECM
Dragging brakesCondition “Dragging brakes” in “Brakes
Symptom Diagnosis in Section 4A”
Slipping clutch (for M/T model)Condition “Slipping clutch” in “Clutch System
Symptom Diagnosis in Section 5C” (for M/T
model)
Low compression“Compression Check in Section 1D”
Camshaft position control (VVT) system
out of order (for engine with VVT
system)“Oil Control Valve Inspection (For Engine with
VVT) in Section 1D” Condition Possible cause Correction / Reference Item
Downloaded from www.Manualslib.com manuals search engine 1A-50 Engine General Information and Diagnosis:
Improper engine idling or
engine fails to idleFaulty spark plug“Spark Plug Inspection in Section 1H”
Leaky or disconnected high-tension cord“High-Tension Cord Removal and Installation
in Section 1H”
Faulty ignition coil with ignitor“Ignition Coil Assembly (Including Ignitor)
Inspection in Section 1H”
Fuel pressure out of specification“Fuel Pressure Check”
Leaky manifold, throttle body, or cylinder
head gasket
Malfunctioning EGR valve“EGR Valve Inspection (If Equipped) in Section
1B”
Faulty evaporative emission control
system“EVAP Canister Purge Inspection in Section
1B”
Faulty EGR system“EGR System Inspection (If Equipped) in
Section 1B”
Faulty fuel injector(s)“Fuel Injector Circuit Check”
Poor performance of ECT sensor or
MAF sensor“Engine Coolant Temperature (ECT) Sensor
Inspection in Section 1C”, or “Intake Air
Temperature (IAT) Sensor Inspection in
Section 1C”
Faulty electric throttle body assembly“Electric Throttle Body Assembly On-Vehicle
Inspection in Section 1C”
Faulty APP sensor assembly“Accelerator Pedal Position (APP) Sensor
Assembly Inspection in Section 1C”
Faulty ECM
Loose connection or disconnection of
vacuum hoses
Malfunctioning PCV valve“PCV Valve Inspection in Section 1B”
Engine overheatingCondition “Engine overheating”
Low compression“Compression Check in Section 1D”
Camshaft position control (VVT) system
out of order (for engine with VVT
system)“Oil Control Valve Inspection (For Engine with
VVT) in Section 1D” Condition Possible cause Correction / Reference Item
Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-51
Excessive hydrocarbon
(HC) emission or carbon
monoxide (CO)Faulty spark plug“Spark Plug Inspection in Section 1H”
Leaky or disconnected high-tension cord“High-Tension Cord Removal and Installation
in Section 1H”
Faulty ignition coil with ignitor“Ignition Coil Assembly (Including Ignitor)
Inspection in Section 1H”
Low compression“Compression Check in Section 1D”
Lead contamination of three way
catalytic converterCheck for absence of filler neck restrictor.
Faulty evaporative emission control
system“EVAP Canister Purge Inspection in Section
1B”
Fuel pressure out of specification“Fuel Pressure Check”
Closed loop system (A/F feedback
compensation) fails (Poor performance
of ECT sensor or MAF sensor)“Engine Coolant Temperature (ECT) Sensor
Inspection in Section 1C” or “Intake Air
Temperature (IAT) Sensor Inspection in
Section 1C”
Faulty electric throttle body assembly“Electric Throttle Body Assembly On-Vehicle
Inspection in Section 1C”
Faulty APP sensor assembly“Accelerator Pedal Position (APP) Sensor
Assembly Inspection in Section 1C”
Faulty injector(s)“Fuel Injector Circuit Check”
Faulty ECM
Engine not at normal operating
temperature
Clogged air cleaner“Air Cleaner Filter Inspection and Cleaning in
Section 1D”
Vacuum leaks“Engine Vacuum Check in Section 1D”
Camshaft position control (VVT) system
out of order (for engine with VVT
system)“Oil Control Valve Inspection (For Engine with
VVT) in Section 1D”
Excessive nitrogen
oxides (NOx) emissionImproper ignition timing“Ignition Timing Inspection in Section 1H”
Lead contamination of catalytic
converterCheck for absence of filler neck restrictor.
Faulty EGR system“EGR System Inspection (If Equipped) in
Section 1B”
Fuel pressure out of specification“Fuel Pressure Check”
Closed loop system (A/F feedback
compensation) fails (Poor performance
of ECT sensor or MAF sensor)“Engine Coolant Temperature (ECT) Sensor
Inspection in Section 1C” or “Intake Air
Temperature (IAT) Sensor Inspection in
Section 1C”
Faulty electric throttle body assembly“Electric Throttle Body Assembly On-Vehicle
Inspection in Section 1C”
Faulty APP sensor assembly“Accelerator Pedal Position (APP) Sensor
Assembly Inspection in Section 1C”
Faulty injector(s)“Fuel Injector Circuit Check”
Faulty ECM
Camshaft position control (VVT) system
out of order (for engine with VVT
system)“Oil Control Valve Inspection (For Engine with
VVT) in Section 1D” Condition Possible cause Correction / Reference Item
Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-111
DTC Troubleshooting
NOTE
If the vehicle runs under fuel deficient condition (such as a condition in which the fuel pump is unable
to draw fuel properly), DTC of misfire may possibly be detected due to fuel pressure drop even though
there is no abnormal condition existing in the Engine and Emission System.
Therefore, if the DTC still cannot be detected with “Trouble Symptom Confirmation” executed in
accordance with “Engine and Emission Control System Check” the possible cause may be due to a
running condition under insufficient fuel supply at the time of detecting DTC of misfire.
Step Action Yes No
1Was “Engine and Emission Control System Check”
performed?Go to Step 2. Go to “Engine and
Emission Control
System Check”.
2Does fuel level meter indicate “E” level (empty)?Add fuel and recheck. Go to Step 3.
3Fuel quality check
1) Check that there is fuel of good quality in the fuel tank.
Is it OK?Go to Step 4. Clean in fuel system
circuit and change fuel.
4Ignition system check
1) Check spark plug and ignition spark of cylinder where
misfire occurs, referring to “Spark Plug Inspection in
Section 1H” and “Ignition Spark Test in Section 1H”.
Are they in good condition?Go to Step 5. Faulty ignition coil, wire
harness, spark plug or
other system parts.
5Fuel injector circuit check
1) Using sound scope, check each injector operating sound
at engine cranking or idling.
Do all injectors make operating sound?Go to Step 6. Check coupler
connection and wire
harness of injector not
making operating sound
and injector itself. If OK,
substitute a known-
good ECM and recheck.
6Fuel pressure check
1) Check fuel pressure referring to “Fuel Pressure Check”.
Is check result satisfactory?Go to Step 7. Repair or replace fuel
system.
7Fuel injector check
1) Check fuel injector(s) referring to “Fuel Injector
Inspection in Section 1G”.
Is check result satisfactory?Go to Step 8. Replace defective
injector.
8Ignition timing check
1) Check ignition timing referring to “Ignition Timing
Inspection in Section 1H”.
Is check result satisfactory?Go to Step 9. Check related sensors.
9EGR system check
1) Check EGR system referring to “EGR System Inspection
(If Equipped) in Section 1B”.
Is check result satisfactory?Go to Step 10. Repair or replace EGR
system.
10Exhaust system check
1) Check exhaust system for exhaust gas clogged.
Is it OK?Go to Step 11. Repair clogged of
exhaust system.