Engine General Information and Diagnosis: 1A-41
Engine Symptom Diagnosis
S7RS0B1104010
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 “APP Sensor Assembly Inspection in Section
1C”
Faulty ECT sensor or MAF sensor “ECT Sensor Inspection in Section 1C” or
“MAF and 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
“Oil Control Valve Inspection in Section 1D”
Faulty EGR system “EGR System Inspection in Section 1B”
Low oil pressure Improper 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
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”
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