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
