Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual - part 181
ME(w/o STI)-105
Engine Trouble in General
MECHANICAL
2. Rough idle and engine
stall
Engine control system <Ref. to EN(H4DOTC)(diag)-2, Basic Diagnostic Procedure.>
A
Intake system
Loosened or cracked intake duct
A
Loosened or cracked PCV hose
A
Loosened or cracked vacuum hose
A
Defective intake manifold gasket
B
Defective throttle body gasket
B
Defective PCV valve
C
Loosened oil filler cap
B
Dirty air cleaner element
C
Fuel line
Defective fuel pump and relay
C
Clogged fuel line
C
Lack of fuel or insufficient fuel
B
Timing belt
Defective timing
C
Compression
Incorrect valve clearance
B
Loosened spark plug or defective gasket
B
Loosened cylinder head bolt or defective cylinder head
gasket
B
Improper valve sealing
B
Defective valve stem
C
Worn or broken valve spring
B
Worn or stuck piston rings, cylinder and piston
B
Incorrect valve timing
A
Improper engine oil (low viscosity)
B
Lubrication system
Incorrect oil pressure
B
Defective rocker cover gasket
C
Cooling system
Over-heating
C
Others
Evaporative emission control system malfunction
A
Stuck or damaged throttle valve
B
Symptoms
Problem parts etc.
Possible cause
RANK