YH4
GRAND
VITARA
ENGINE DIAGNOSIS (G16/J20 ENGINES) 6-29
ENGINE DIAGNOSIS TABLE
Perform troubleshooting referring to following table when ECM (PCM) has detected no DTC and no abnormality
has been found in visual inspection and engine basic inspection previously.
Condition
Possible Cause Reference Item
Hard starting
(Engine cranks OK)
Engine and emission control system
out of order.
Faulty idle air control system
Faulty ECT sensor or MAF sensor
Faulty ECM (PCM)
Low compression.
Faulty hydraulic valve lash adjuster
Compression leak from valve seat
Sticky valve stem
Weak or damaged valve springs
Compression leak at cylinder head
gasket
Sticking or damaged piston ring
Worn piston, ring or cylinder
Others
Malfunctioning PCV valve
DTC P0505 Diag. Flow Table or Table
B-4 in this Section.
ECT sensor or MAF sensor in Engine
and Emission Control System
Section.
Inspection of ECM (PCM) and its
circuit in this Section.
Compression check in Engine
Mechanical Section.
Valve lash adjuster in Engine
Mechanical Section.
Valves inspection in Engine
Mechanical Section.
Valves inspection in Engine
Mechanical Section.
Valves spring inspection in Engine
Mechanical Section.
Cylinder head inspection in Engine
Mechanical Section.
Piston ring inspection in Engine
Mechanical Section.
Cylinders, pistons and piston rings
inspection in Engine Mechanical
Section.
PCV system inspection in Engine and
Emission Control System Section.
Engine has no power Engine overheating.
Ignition system out of order.
Defective spark plug.
Faulty ignition coil with ignitor
Fuel system out of order.
Fuel pressure out of specification
– Dirty fuel filter
– Dirty or clogged fuel hose or pipe
– Malfunctioning fuel pressure regulator
– Malfunctioning fuel pump
Engine and emission control system
out of order.
Maladjusted TP sensor installation
angle
Faulty EGR system
Faulty injector
Faulty TP sensor, ECT sensor or
MAF sensor
Faulty ECM (PCM)
Low compression.
Others
Dragging brakes
Slipping clutch
Refer to “Overheating” Section.
Spark plugs in Ignition System
Section.
Ignition coil in Ignition System
Section.
Diag. Flow Table B-3 in this Section.
TP sensor in Engine and Emission
Control System Section.
DTC P0400 Diag. Flow Table in this
Section.
Fuel injector in Engine and Emission
Control System Section.
TP sensor, ECT sensor or MAF
sensor in Engine and Emission
Control System Section.
Inspection of ECM (PCM) and its
circuit in this Section.
Previously outlined.
Diagnosis in BRAKES Section.
Diagnosis in Clutch Section.
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