Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Service manual - part 243
EN(H4DOTC)(diag)-196
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
13
CHECK CAUSE OF MISFIRE.
Was the cause of misfire identi-
fied when the engine is run-
ning?
Finish diagnostics
operation, if the
engine has no
abnormality.
Repair the poor
contact of connec-
tor.
NOTE:
In this case, repair
the following item:
• Poor contact of
ignition coil con-
nector
• Poor contact of
fuel injector con-
nector on faulty
cylinders
• Poor contact of
ECM connector
• Poor contact of
coupling connector
14
CHECK AIR INTAKE SYSTEM.
Is there any fault in air intake
system?
Repair the air
intake system.
NOTE:
Check the follow-
ing items.
• Are there air
leaks or air suction
caused by loose or
dislocated
nuts
and bolts?
• Are there cracks
or any disconnec-
tion of hoses?
15
CHECK ALL CYLINDERS.
Is there a fault in any cylinder? Repair or replace
the faulty part of
the faulty cylinder.
NOTE:
Check the follow-
ing items.
• Spark plug
• Fuel injector
• Ignition coil
• Compression ra-
tio
• Skipping timing
belt teeth
Step
Check
Yes
No