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6-28 ENGINE GENERAL INFORMATION AND DIAGNOSIS
Condition
Poor gasoline mile-
age
Excessive engine
oil consumption
Engine hesitates
(Momentary lack of
response as accel-
erator is depressed.
Can occur at all
vehicle speeds.
Usually most severe
when first trying to
make vehicle move,
as from a stop sign.)
Surge
(Engine power vari-
ation under steady
throttle or cruise.
Feels like vehicle
speeds up and
down with no
change in accelera-
tor pedal.)
Possible Cause
Leaks or loose connection of high-tension
cord
Faulty spark plug (improper gap, heavy
deposits and burned electrodes, etc.)
Malfunctioning EGR valve (if equipped)
High idle speed
Poor performance of TP sensor, ECT sensor
or MAP sensor
Faulty EGR valve (if equipped)
Faulty fuel injector(s)
Faulty ECM
Poor valve seating
Dragging brakes
Slipping clutch
Thermostat out of order
Improper tire pressure
Low Compression
Blown cylinder head gasket
Leaky camshaft oil seals
Sticky piston ring
Worn piston and cylinder
Worn piston ring groove and ring
Improper location of piston ring gap
Worn or damaged valve stem seal
Worn valve stem
Spark plug faulty or plug gap out of adjust-
ment
Leaky high-tension cord
Fuel pressure out of specification
Malfunctioning EGR valve (if equipped)
Poor performance of TP sensor, ECT sensor
or MAP sensor
Faulty fuel injector
Faulty ECM
Engine overheating
Low compression
Leaky or loosely connected high-tension cord High-tension cords in Section 6F1.
Faulty spark plug (excess carbon deposits,
improper gap, and burned electrodes, etc.)
Variable fuel pressure
Kinky or damaged fuel hose and lines
Faulty fuel pump (clogged fuel filter)
Malfunctioning EGR valve
Poor performance of MAP sensor
Faulty fuel injector
Faulty ECM
Correction
High-tension cords in Section 6F1.
Spark plugs in Section 6F1.
EGR system in Section 6E1.
Refer to item "Improper engine idle
speed" previously outlined.
TP sensor, ECT sensor or MAP sensor
in Section 6E1.
EGR system in Section 6E1.
Diagnostic Flow Table B-1.
Valves inspection in Section 6A1.
Trouble diagnosis in Section 5.
Trouble diagnosis in Section 7C.
Thermostat in Section 6B.
Refer to Section 3F.
Previously outlined
Cylinder head in Section 6A1.
Camshaft in Section 6A1.
Piston cleaning in Section 6A1.
Pistons and cylinders inspection in Sec-
tion 6A1.
Pistons inspection in Section 6A1.
Pistons assembly in Section 6A1.
Valves removal and installation in Sec-
tion 6A1.
Valves inspection in Section 6A1.
Spark plugs in Section 6F1.
High-tension cords in Section 6F1.
Diagnostic Flow Table B-3.
EGR system in section 6E1.
TP sensor, ECT sensor or MAP sensor
in Section 6E1.
Diagnostic Flow Table B-1.
Refer to "Overheating" section.
Previously outlined.
Spark plugs in Section 6F1.
Diagnostic Flow Table B-3.
EGR system in Section 6E1.
MAP sensor in Section 6E1.
Diagnostic Flow Table B-1.
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