Engine Symptom Diagnosis
Precautions: General safety (00)
Perform troubleshooting referring to the following points when ECM has detected no DTC and no abnormality has been found in Visual Inspection:M16A and Engine Basic Inspection:M16A.
| Condition | Possible Cause | Action |
|---|---|---|
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Hard starting (Engine can be cranked)
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Faulty spark plug
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Faulty ignition coil
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Dirty or clogged fuel hoses or pipes
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Malfunctioning fuel pump
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Air drawn in through intake manifold gasket or throttle body gasket
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Check air intake system.
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Faulty electric throttle body assembly
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Faulty APP sensor
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Faulty ECT sensor or MAP sensor
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Faulty ECM
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Low compression
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Poor spark plug tightening or faulty gasket
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Compression leakage from valve seat
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Sticky valve stem
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Weak or damaged valve springs
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Compression leakage at cylinder head gasket
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Sticky or damaged piston ring
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Worn piston, piston ring or cylinder
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Malfunctioning PCV valve
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VVT system out of order
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•VVT actuator: VVT Actuator, Camshaft, Tappet and Shim Inspection:M16A
•Valve timing: Timing Chain and Chain Tensioner Inspection:M16A •OCV oil circuit: Timing Chain Cover Inspection:M16A |
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Low oil pressure
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Improper oil viscosity
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Malfunctioning oil pressure switch
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Clogged oil strainer
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Check oil strainer for clog.
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Functional deterioration of oil pump
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Worn oil pump relief valve
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Excessive clearance in various sliding parts
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—
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Engine noise – Valve noise
NOTE:
Before checking mechanical noise, check that:
•Specified spark plug is used.
•Specified fuel is used. |
Improper valve clearance
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Worn valve stem and guide
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Weak or broken valve spring
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Warped or bent valve
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Engine noise – Piston, piston ring and cylinder noise
NOTE:
Before checking mechanical noise, check that:
•Specified spark plug is used.
•Specified fuel is used. |
Worn piston, piston ring and cylinder bore
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Engine noise – Connecting rod noise
NOTE:
Before checking mechanical noise, check that:
•Specified spark plug is used.
•Specified fuel is used. |
Worn piston, piston ring and cylinder bore
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Worn connecting rod bearing
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Worn crankshaft pin
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Loose connecting rod bolts
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Low oil pressure
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Condition “Low oil pressure”
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Engine noise – Crankshaft noise
NOTE:
Before checking mechanical noise, check that:
•Specified spark plug is used.
•Specified fuel is used. |
Low oil pressure
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Condition “Low oil pressure”
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Worn main bearing
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Worn crankshaft journal
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Loose bearing cap bolts
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Excessive crankshaft thrust play
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Engine overheating
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Inoperative thermostat
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Poor water pump performance
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Clogged or leaky radiator
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Improper engine oil grade
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Clogged oil filter or oil strainer
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Poor oil pump performance
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Faulty radiator cooling fan control system
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Dragging brakes
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Condition “Dragging brakes” in Brake Symptom Diagnosis
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Slipping clutch (M/T model)
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Condition “Slipping” in Clutch System Symptom Diagnosis:5 M/T
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Blown cylinder head gasket
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Air mixed in cooling system
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Poor fuel mileage
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Faulty spark plug (improper gap, heavy deposits and burned electrodes, etc.)
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High idle speed
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Condition “Improper engine idling or engine fails to idle”
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Poor performance of ECT sensor or MAP sensor
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Faulty electric throttle body assembly
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Faulty APP sensor
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Faulty fuel injector
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Faulty ECM
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Low compression
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Poor valve seating
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Dragging brakes
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Condition “Dragging brakes” in Brake Symptom Diagnosis
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Slipping clutch (M/T model)
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Condition “Slipping” in Clutch System Symptom Diagnosis:5 M/T
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Thermostat out of order
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Improper tire pressure
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VVT system out of order
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•VVT actuator: VVT Actuator, Camshaft, Tappet and Shim Inspection:M16A
•Valve timing: Timing Chain and Chain Tensioner Inspection:M16A •OCV oil circuit: Timing Chain Cover Inspection:M16A |
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Excessive engine oil consumption – Oil leakage
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Broken cylinder head gasket
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Leaky crankshaft pulley oil seal
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Leaky crankshaft rear oil seal
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Leaky cylinder head cover gasket
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Excessive engine oil consumption – Oil entering combustion chamber
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Sticky piston ring
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Worn piston and cylinder
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Worn piston ring groove and ring
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Improper location of piston ring gap
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Worn or damaged valve stem seal
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Worn valve stem
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Engine hesitates – Momentary lack of response as accelerator is depressed. Can occur at all vehicle speeds. Usually severest when moving out from a stop at stop signal etc.
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Faulty spark plug or plug gap out of adjustment
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Fuel pressure out of specification
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Poor performance of ECT sensor or MAP sensor
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Faulty electric throttle body assembly
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Faulty APP sensor
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Faulty fuel injector
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Faulty ECM
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Engine overheating
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Condition “Engine overheating”
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Low compression
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Surge – Engine power variation under steady throttle or cruise. Vehicle speed changes up and down with no change in accelerator pedal position.
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Faulty spark plug (excessive carbon deposits, improper gap, burned electrodes, etc.)
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Variable fuel pressure
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Kinky or damaged fuel lines
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Faulty fuel pump (clogged fuel filter)
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Poor performance of MAP sensor
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Faulty fuel injector
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Faulty ECM
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Faulty electric throttle body assembly
|
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Faulty APP sensor
|
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VVT system out of order
|
•VVT actuator: VVT Actuator, Camshaft, Tappet and Shim Inspection:M16A
•Valve timing: Timing Chain and Chain Tensioner Inspection:M16A •OCV oil circuit: Timing Chain Cover Inspection:M16A |
|
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Excessive detonation – Engine continuously generates sharp, metallic knocking sound that changes with throttle opening.
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Faulty spark plug
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Engine overheating
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Condition “Engine overheating”
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Clogged fuel filter (faulty fuel pump) or fuel lines
|
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Air drawn in through intake manifold or throttle body gasket
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Check air intake system.
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Poor performance of knock sensor, ECT sensor or MAP sensor
|
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Faulty fuel injector
|
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Faulty ECM
|
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Excessive combustion chamber deposits
|
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VVT system out of order
|
•VVT actuator: VVT Actuator, Camshaft, Tappet and Shim Inspection:M16A
•Valve timing: Timing Chain and Chain Tensioner Inspection:M16A •OCV oil circuit: Timing Chain Cover Inspection:M16A |
|
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Poor engine power
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Faulty spark plug
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Faulty ignition coil assembly
|
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Faulty knock sensor
|
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Clogged fuel hoses or pipes
|
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Malfunctioning fuel pump
|
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Air drawn in through intake manifold gasket or throttle body gasket
|
Check air intake system.
|
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Engine overheating
|
Condition “Engine overheating”
|
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Poor performance of ECT sensor or MAP sensor
|
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Faulty electric throttle body assembly
|
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Faulty APP sensor
|
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Faulty fuel injector
|
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Faulty ECM
|
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Dragging brakes
|
Condition “Dragging brakes” in Brake Symptom Diagnosis
|
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Slipping clutch (M/T model)
|
Condition “Slipping” in Clutch System Symptom Diagnosis:5 M/T
|
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Low compression
|
||
|
VVT system out of order
|
•VVT actuator: VVT Actuator, Camshaft, Tappet and Shim Inspection:M16A
•Valve timing: Timing Chain and Chain Tensioner Inspection:M16A •OCV oil circuit: Timing Chain Cover Inspection:M16A |
|
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Improper engine idling or engine fails to idle
|
Faulty spark plug
|
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Faulty ignition coil assembly
|
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Fuel pressure out of specification
|
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Leaky manifold, throttle body or cylinder head gasket
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Check air intake system.
|
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Faulty evaporative emission control system
|
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Faulty fuel injector
|
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Poor performance of ECT sensor or MAP sensor
|
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Faulty electric throttle body assembly
|
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Faulty APP sensor
|
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Faulty ECM
|
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Loose connection or disconnection of vacuum hoses
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Check connection of vacuum hoses.
|
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Malfunctioning PCV valve
|
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Engine overheating
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Condition “Engine overheating”
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Low compression
|
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Faulty generator and/or its circuit
|
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VVT system out of order
|
•VVT actuator: VVT Actuator, Camshaft, Tappet and Shim Inspection:M16A
•Valve timing: Timing Chain and Chain Tensioner Inspection:M16A •OCV oil circuit: Timing Chain Cover Inspection:M16A |
|
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Excessive hydrocarbon (HC) emission or carbon monoxide (CO) emission
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Faulty spark plug
|
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Faulty ignition coil assembly
|
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Low compression
|
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Lead contamination of TWC
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Check for absence of filler neck restrictor.
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Faulty evaporative emission control system
|
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Fuel pressure out of specification
|
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Faulty closed loop system (A/F feedback compensation) (Poor performance of ECT sensor or MAP sensor)
|
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Faulty electric throttle body assembly
|
||
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Faulty APP sensor
|
||
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Faulty fuel injector
|
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Faulty ECM
|
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Engine not at normal operating temperature
|
—
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Clogged air cleaner
|
||
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Vacuum leakage
|
||
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VVT system out of order
|
•VVT actuator: VVT Actuator, Camshaft, Tappet and Shim Inspection:M16A
•Valve timing: Timing Chain and Chain Tensioner Inspection:M16A •OCV oil circuit: Timing Chain Cover Inspection:M16A |
|
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Excessive nitrogen oxides (NOx) emission
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Improper ignition timing
|
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Lead contamination of TWC
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Check for absence of filler neck restrictor.
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Fuel pressure out of specification
|
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Faulty closed loop system (A/F feedback compensation) (Poor performance of ECT sensor or MAP sensor)
|
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Faulty electric throttle body assembly
|
||
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Faulty APP sensor
|
||
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Faulty fuel injector
|
||
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Faulty ECM
|
||
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VVT system out of order
|
•VVT actuator: VVT Actuator, Camshaft, Tappet and Shim Inspection:M16A
•Valve timing: Timing Chain and Chain Tensioner Inspection:M16A •OCV oil circuit: Timing Chain Cover Inspection:M16A |