Suzuki Engine 2002 GRAND VITARA SQ625, Service Manual

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6-1-38 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H25 ENGINE)
Excessive detona-
tion (The engine
makes sharp
metallic knocks
that change with
throttle opening.
Sounds like pop
corn popping.) Engine overheating Refer to “Overheating” in this table.
Ignition system out of order.
• Faulty spark plug
“Spark Plugs” in Section 6F2.
• Improper ignition timing “Ignition Timing Check and Adjustment” in
Section 6F2.
Fuel system out of order.
• Clogged fuel filter and fuel lines
“Fuel Pressure Check” in Section 6E2.
Engine and emission control system out of
order.
• Faulty EGR system
“DTC P0400 Diag. Flow Table” in this sec-
tion.
• Faulty ECT sensor or MAF sensor “ECT Sensor” or “MAF Sensor” in Section
6E2.
• Faulty injector “Fuel Injector” in Section 6E2.
• Faulty ECM (PCM) “Inspection of ECM (PCM) and Its Circuit” in
this section.
Others
• Excessive combustion chamber depos-
its
“Valves and Cylinder Heads” and “Pistons,
Piston Rings, Connecting Rods and Cylin-
ders” in Section 6A2.
Overheating • Inoperative thermostat “Thermostat” in Section 6B.
• Poor water pump performance “Water Pump” in Section 6B.
• Clogged or leaky radiator “Radiator” in Section 6B.
• Improper engine oil grade “Engine Oil and Oil Filter Change” in Sec-
tion 0B.
• Clogged oil filter or oil strainer “Oil Pressure Check” in Section 6A2.
• Poor oil pump performance “Oil Pressure Check” in Section 6A2.
• Dragging brakes “Diagnosis Table” in Section 5.
• Slipping clutch “Diagnosis Table” in Section 7C.
• Blown cylinder head gasket “Valves and Cylinder Heads” in Section
6A2.
• Faulty A/C condenser fan control system “Diag. Flow Table B-5” in this section.
Condition Possible Cause Correction