Subaru IMPREZA 2002 Service Manual page 190

Fuel line
Defective throttle body gasket B
Defective PCV valve B
Loosened oil filler cap B
Dirty air cleaner element A
Defective fuel pump and relav
B
Belt
Compression
Defective timing B
Incorrect valve clearance B
Loosened spark plugs or defective gasket B
Loosened cvlinder head bolts or defective aasket B
Lubrication svstem
Worn or stuck piston rings, cylinder and piston C
Incorrect valve timing A
Improper engine oil (low viscosity) B
Incorrect oil pressure B
Cooling system Overheating I C
Over
coolina I C
Others
Engine control system <Ref. to EN(SOHC)Q, Basic Diagnostic Procedure.>
Intake system
I
Malfunction of evaporative emission control system
Loosened or cracked intake duct
Loosened or cracked PCV hose
A
A
A
A
Defective throttle body gasket
Defective PCV valve
Loosened oil filler caD
B
B
B
Lack of or insufficient fuel
Defective timing
Incorrect valve clearance
Loosened spark Dluas or defective aasket
C
B
B
C
Defective valve stem
Worn or broken valve spring
Worn or stuck piston rings, cylinder and piston
Incorrect valve timina
C
C
C
A
ENGINE TROUBLE IN GENERAL
MECHANICAL
-PROBLEM PARTS, ETC.
I
POSSIBLE CAUSE
I
RANK
I
TROUBLE
3. Low output, hesitation and
ioor acceleration
Engine control system <Ref. to EN(S0HC)-2, Basic Diagnostic Procedure.>
I A
Intake system Loosened or cracked intake duct
Loosened or cracked PCV hose
I A
I A
I *
Loosened or cracked vacuum hose
1 B 1
I
Defective intake manifold gasket
1 B 1
I
Clogged fuel line
1 B 1
I
Lack of or insufficient fuel
I C 1
I
Improper valve seating
1 B 1
I
Defective valve stem
I C 1
I
Worn or broken valve spring
1 B 1
4. Surging
I
Loosened or cracked vacuum hose
I A I
I
Defective intake manifold gasket
1 B 1
I
Dirty air cleaner element
I
Defective fuel pump and relav
I B
I B
Fuel line
I
Clogged fuel line
1 B 1
Belt
Compression
r*
Loosened cvlinder head bolts or defective gasket
I
C
I
I
Improper valve seating
I C 1
I
Improperengine oil (low viscosity)
I B
Coolina svstem
I
Overheating I B
Others
I
Malfunction of evaporative emission control system
I
C
I
ME(S0HC)-92