Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual - part 86

ME(STI)-106

Crankshaft

MECHANICAL

24.Crankshaft

A: SPECIFICATION

Refer to “Cylinder Block” for removal and installa-

tion  procedures  of  the  crankshaft.  <Ref.  to

ME(STI)-80, REMOVAL, Cylinder Block.> <Ref. to

ME(STI)-84, INSTALLATION, Cylinder Block.>

ME(STI)-107

Engine Trouble in General

MECHANICAL

25.Engine Trouble in General

A: INSPECTION

NOTE:

The “RANK” shown in the chart shows the possibilities of the cause of trouble in order from “Very often” to

“Rarely”.

A — Very often

B — Sometimes

C — Rarely

Symptoms

Problem parts etc.

Possible cause

RANK

1. Engine does not start.

 

1) Starter does not turn.

Starter

Defective battery-to-starter harness

B

Defective starter switch

C

Defective starter

B

Battery

Improper connection of terminal

A

Run-down battery

A

Defective charging system

B

Friction

Seizure of crankshaft and connecting rod bearing

C

Seized camshaft

C

Seized or stuck piston and cylinder

C

Immobilizer system <Ref. to IM(diag)-2, Basic Diagnostic Procedure.>

A

2) Initial combustion does 
not occur.

Starter

Defective starter

C

Engine control system <Ref. to EN(H4DOTC)(diag)-2, Basic Diagnostic Procedure.>

A

Fuel line

Defective fuel pump and relay

A

Clogged fuel line

C

Lack of fuel or insufficient fuel

B

Timing belt

Degradation, etc.

B

Defective timing

B

Compression

Incorrect valve clearance

C

Loosened spark plug or defective gasket

C

Loosened cylinder head bolt or defective cylinder head 
gasket

C

Improper valve sealing

C

Defective valve stem

C

Worn or broken valve spring

B

Worn or stuck piston rings, cylinder and piston

C

Incorrect valve timing

B

Improper engine oil (low viscosity)

B

ME(STI)-108

Engine Trouble in General

MECHANICAL

3) Initial combustion occurs.

Engine control system <Ref. to EN(H4DOTC)(diag)-2, Basic Diagnostic Procedure.>

A

Intake system

Defective intake manifold gasket

B

Defective throttle body gasket

B

Fuel line

Defective fuel pump and relay

C

Clogged fuel line

C

Lack of fuel or insufficient fuel

B

Timing belt

Degradation, etc.

B

Defective timing

B

Compression

Incorrect valve clearance

C

Loosened spark plug or defective gasket

C

Loosened cylinder head bolt or defective cylinder head 
gasket

C

Improper valve sealing

C

Defective valve stem

C

Worn or broken valve spring

B

Worn or stuck piston rings, cylinder and piston

C

Incorrect valve timing

B

Improper engine oil (low viscosity)

B

4) Engine stalls after initial 
combustion.

Engine control system <Ref. to EN(H4DOTC)(diag)-2, Basic Diagnostic Procedure.>

A

Intake system

Loosened or cracked intake duct

B

Loosened or cracked PCV hose

C

Loosened or cracked vacuum hose

C

Defective intake manifold gasket

B

Defective throttle body gasket

B

Dirty air cleaner element

C

Fuel line

Clogged fuel line

C

Lack of fuel or insufficient fuel

B

Timing belt

Degradation, etc.

B

Defective timing

B

Compression

Incorrect valve clearance

C

Loosened spark plug or defective gasket

C

Loosened cylinder head bolt or defective cylinder head 
gasket

C

Improper valve sealing

C

Defective valve stem

C

Worn or broken valve spring

B

Worn or stuck piston rings, cylinder and piston

C

Incorrect valve timing

B

Improper engine oil (low viscosity)

B

Symptoms

Problem parts etc.

Possible cause

RANK

ME(STI)-109

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