ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10) 6-25
ConditionPossible CauseReferring Item
Engine hesitates
(Momentary lack of
response as
accelerator is
depressed.
Can occur at all
vehicle speeds.
Usually most severe
when first trying to
make vehicle move,
as from a stop sign.)Ignition system out of order
Spark plug faulty or plug gap out of adjustment
Leaky high-tension cord
Fuel system out of order
Fuel pressure out of specification
Engine and emission control system out of
order
Poor performance of TP sensor, ECT sensor or
MAP sensor
Faulty fuel injector
Faulty ECM (PCM)
Engine overheating
Low compression
Spark plugs in Section 6F
High-tension cords in Section 6F
Diagnostic Flow Table B-3
Trouble diagnosis in Section 6
TP sensor, ECT sensor or MAP
sensor in Section 6E1
Diagnostic Flow Table B-1
Refer to “Overheating” section
Previously outlined
Surge
(Engine power
variation under
steady throttle or
cruise.
Feels like vehicle
speeds up and down
with no change in
accelerator pedal.)Ignition system out of order
Leaky or loosely connected high-tension cord
Faulty spark plug (excess carbon deposits,
improper gap, and burned electrodes, etc.)
Fuel system out of order
Variable fuel pressure
Kinky or damaged fuel hose and lines
Faulty fuel pump (clogged fuel filter)
Engine and emission control system out of
order
Poor performance of MAP sensor
Faulty fuel injector
Faulty ECM (PCM)
High-tension cords in Section 6F
Spark plugs in Section 6F
Diagnostic Flow Table B-3
MAP sensor in Section 6E1
Diagnostic Flow Table B-1
Excessive
detonation
(Engine makes
continuously
sharp metallic
knocks that change
with throttle opening.
Sounds like pop corn
popping.)Engine overheating
Ignition system out of order
Faulty spark plug
Loose connection of high-tension cord
Fuel system out of order
Clogged fuel filter (faulty fuel pump) or fuel lines
Air inhaling from intake manifold or throttle body
gasket
Engine and emission control system out of
order
Poor performance of ECT sensor or MAP sensor
Faulty fuel injector
Faulty ECM (PCM)
Excessive combustion chamber depositsRefer to “Overheating” section
Spark plugs in Section 6F
High-tension cords in Section 6F
Diagnostic Flow Table B-1 or B-2
Trouble diagnosis in Section 6
ECT sensor or MAP sensor in
Section 6E1
Diagnostic Flow Table B-1
Piston and cylinder head cleaning
in Section 6A
ENGINE GENERAL INFORMATION AND DIAGNOSIS (SFI FOR G13) 6-1-25
ConditionPossible CauseReferring Item
Engine hesitates
(Momentary lack of
response as
accelerator is
depressed.
Can occur at all
vehicle speeds.
Usually most severe
when first trying to
make vehicle move,
as from a stop sign.)Ignition system out of order
Spark plug faulty or plug gap out of adjustment
Leaky high-tension cord
Fuel system out of order
Fuel pressure out of specification
Engine and emission control system out of
order
Malfunctioning EGR valve
Poor performance of TP sensor, ECT sensor or
MAP sensor
Faulty fuel injector
Faulty ECM (PCM)
Engine overheating
Low compression
Spark plugs in Section 6F1
High-tension cords in Section 6F1
Diagnostic Flow Table B-3
EGR system in section 6E2
TP sensor, ECT sensor or MAP
sensor in Section 6E2
Diagnostic Flow Table B-1
Refer to “Overheating” section
Previously outlined
Surge
(Engine power
variation under
steady throttle or
cruise.
Feels like vehicle
speeds up and down
with no change in
accelerator pedal.)Ignition system out of order
Leaky or loosely connected high-tension cord
Faulty spark plug (excess carbon deposits,
improper gap, and burned electrodes, etc.)
Fuel system out of order
Variable fuel pressure
–Kinky or damaged fuel hose and lines
–Faulty fuel pump (clogged fuel filter)
Engine and emission control system out of
order
Malfunctioning EGR valve
Poor performance of MAP sensor
Faulty fuel injector
Faulty ECM (PCM)
High-tension cords in Section 6F1
Spark plugs in Section 6F1
Diagnostic Flow Table B-3
EGR system in Section 6E2
MAP sensor in Section 6E2
Diagnostic Flow Table B-1
Excessive
detonation
(Engine makes
continuously
sharp metallic
knocks that change
with throttle opening.
Sounds like pop corn
popping.)Engine overheating
Ignition system out of order
Faulty spark plug
Loose connection of high-tension cord
Fuel system out of order
Clogged fuel filter (faulty fuel pump) or fuel lines
Air inhaling from intake manifold or throttle body
gasket
Engine and emission control system out of
order
Malfunctioning EGR valve
Poor performance of ECT sensor or MAP sensor
Faulty fuel injector(s).
Faulty ECM (PCM)
Excessive combustion chamber depositsRefer to “Overheating” section
Spark plugs in Section 6F1
High-tension cords in Section 6F1
Diagnostic Flow Table B-1 or B-2
EGR system in Section 6E2
ECT sensor or MAP sensor in
Section 6E2
Diagnostic Flow Table B-1
Piston and cylinder head cleaning
in Section 6A1
