Suzuki 2000 Grand Vitara SQ625 Service Manual page 35

Condition
Surges
(Engine power variation
under steady throttle or
cruise.
Feels like the vehicle
speeds up and down
with no change in the
accelerator pedal.)
Excessive detonation
(The engine makes
sharp metallic knocks
that change with throttle
opening.
Sounds like pop corn
popping.)
Possible Cause
Ignition system out of order.
D Defective spark plug (excess carbon
deposits, improper gap, and burned
electrodes, etc.)
Fuel system out of order.
D Variable fuel pressure
– Clogged fuel filter
– Kinky or damaged fuel hose and line
– Faulty fuel pressure regulator
Engine and emission control system out
of order.
D Faulty EGR system
D Faulty MAF sensor
D Faulty injector
D Faulty ECM (PCM)
Engine overheating
Ignition system out of order.
D Faulty spark plug
D Improper ignition timing
Fuel system out of order.
D Clogged fuel filter and fuel lines
Engine and emission control system
out of order.
D Faulty EGR system
D Faulty ECT sensor or MAF sensor
D Faulty injector
D Faulty ECM (PCM)
Others
D Excessive combustion chamber
deposits
ENGINE DIAGNOSIS (G16 / J20 ENGINES) 6-31
Reference Item
Spark plugs in Ignition System
Section.
Diag. Flow Table B-3 in this Section.
DTC P0400 Diag. Flow Table in this
Section.
MAF sensor in Engine and Emission
Control System Section.
Fuel injector in Engine and Emission
Control System Section.
Inspection of ECM (PCM) and its
circuit in this Section.
Refer to "Overheating" Section.
Spark plugs in Ignition System
Section.
Ignition timing in Ignition System
Section.
Fuel pressure check in Engine and
Emission Control System Section.
DTC P0400 Diag. Flow Table in this
Section.
ECT sensor or MAF sensor in Engine
and Emission Control System
Section.
Fuel injector in Engine and Emission
Control System Section.
Inspection of ECM (PCM) and its
circuit in this Section.
Piston and cylinder head cleaning in
Engine Mechanical Section.