🏷️ Basic Information

Make:

Subaru

Model:

Impreza WRX STI

Model Variant:

STI (Turbo) / Impreza (Non-Turbo)

Year:

2005

Chassis Code:

GDB (Impreza chassis)

Engine Code Sti:

EJ257

Engine Code Non Turbo:

EJ204 (commonly found on non-STI Imprezas of this era)

👋 Introduction

Segment:

Performance Compact Sedan/Hatchback

Usp:

Iconic rally heritage, turbocharged performance (STI), symmetrical all-wheel-drive, driver-focused cockpit.

Competitors:

Mitsubishi Lancer Evolution, Honda Civic Si, Volkswagen GTI, Ford Focus SVT.

Performance Focus:

Emphasizes track-capable performance and engaging driving dynamics, particularly in the STI variant.

AWD Capability:

Subaru's renowned Symmetrical All-Wheel Drive system provides superior traction and stability in various conditions.

Durability:

Known for robust engineering and durability, especially in the boxer engine and AWD drivetrain.

📋 Manual Details

Coverage Scope:

All models and all repairs A-Z for 2005 Subaru Impreza WRX STI and non-turbo Impreza variants.

Estimated Page Count:

Approximately 2000+ pages (typical for full factory service manuals of this scope).

Type:

Factory Service Manual / Workshop Manual

Language:

English

Format:

Digital (likely PDF, often with searchable text and high-resolution diagrams)

📖 Manual Coverage

Engine Mechanical:

Engine assembly, disassembly, torque specifications, cylinder head, crankshaft, pistons, connecting rods, valve train, timing belt/chain, lubrication system, cooling system.

Engine Management:

Fuel injection system, ignition system, emission control systems (catalytic converter, EVAP), engine control unit (ECU) diagnosis, sensors and actuators, turbocharger system (STI).

Transmission Manual:

Clutch system, gearbox assembly, disassembly, internal components, gear ratios, shifting mechanisms, driveshafts, differentials.

Transmission Automatic:

If applicable to specific 2005 Impreza models covered, this would include gearbox assembly, hydraulics, torque converter, electronic controls.

Drivetrain:

All-Wheel Drive (AWD) system, viscous coupling, differentials (front, center, rear), hubs, wheel bearings.

Suspension:

Front suspension (struts, control arms, bushings), rear suspension (multi-link design), springs, shock absorbers, sway bars, alignment specifications.

Steering:

Power steering system, steering column, rack and pinion, tie rods, steering knuckle.

Brakes:

Hydraulic brake system, brake calipers, rotors, pads, master cylinder, brake booster, ABS system, parking brake.

Electrical System:

Battery, alternator, starter motor, lighting systems (headlights, taillights, interior), fuses, relays, wiring diagrams.

Body Exterior:

Body panel removal and installation, doors, hood, trunk lid, bumpers, glass, seals, trim.

Body Interior:

Dashboard, seats, upholstery, HVAC system components, interior trim, audio system, airbags.

HVAC:

Heating, ventilation, and air conditioning system components, refrigerant handling, diagnosis.

Routine Maintenance:

Oil changes, filter replacements, fluid checks and top-offs, spark plug replacement, brake fluid flush, coolant flush.

Troubleshooting:

Diagnostic procedures for common drivability issues, electrical faults, component failures, including specific symptom-based troubleshooting trees.

Component Replacement:

Step-by-step instructions for replacing major and minor components across all vehicle systems.

Rebuild Procedures:

Detailed instructions for the complete disassembly, inspection, repair, and reassembly of engine, transmission, and differential components.

Wiring Diagrams:

Comprehensive electrical wiring diagrams for all major systems, including engine control, body electronics, and lighting.

Torque Specifications:

Precise torque values for all critical fasteners, essential for proper assembly and preventing damage.

Special Tools:

Identification and usage of specialized tools required for specific repairs or diagnostics.

Tightening Sequences:

Specific sequences for tightening critical components such as cylinder heads and wheel nuts.

Depth:

Comprehensive, covering basic maintenance to complete engine and transmission rebuilds, including advanced diagnostics and troubleshooting.

📊 Manual Specifications

File Type:

PDF

Searchability:

Searchable text for quick information retrieval.

Image Quality:

High-resolution diagrams and images for clarity.

Print Readability:

Designed for clear readability when printed.

Binding:

N/A (Digital Format)

Paper Quality:

N/A (Digital Format)

⚙️ Engine Specifications

Sti Engine Type:

2.5L EJ257 Flat-Four (Boxer)

Sti Aspiration:

Turbocharged and Intercooled

Sti Horsepower:

Approx. 300 hp @ 6000 rpm (factory rating, often underestimated)

Sti Torque:

Approx. 300 lb-ft @ 4000 rpm (factory rating)

Non Turbo Engine Type:

2.0L EJ204 Flat-Four (Boxer) or similar naturally aspirated variant

Non Turbo Aspiration:

Naturally Aspirated

Non Turbo Horsepower:

Approx. 150-170 hp (typical for non-STI models)

Non Turbo Torque:

Approx. 140-150 lb-ft (typical for non-STI models)

Compression Ratio Sti:

8.0:1

Bore X Stroke Sti:

92.0 mm x 91.0 mm

Fuel Delivery:

Multi-point fuel injection (MPI)

Fuel Type:

Premium Unleaded (91 octane or higher recommended for STI)

Sti Engine Internals:

Forged pistons, stronger connecting rods, sodium-filled exhaust valves (STI specific).

🔧 Transmission

Sti Transmission Type:

6-speed manual

Non Turbo Transmission Type:

5-speed manual or 4-speed automatic (depending on trim/market)

AWD System:

Symmetrical All-Wheel Drive with Driver Controlled Center Differential (DCCD) on STI models.

Sti Gearbox Fluid:

Subaru ExtraS PS Fluid (or equivalent API GL-5 75W-90 synthetic gear oil)

AWD Differential Fluid:

Subaru ExtraS PS Fluid (or equivalent API GL-5 75W-90 synthetic gear oil)

📐 Dimensions

Wheelbase:

Approx. 103.1 inches (2619 mm)

Length:

Approx. 174.5 inches (4432 mm)

Width:

Approx. 69.7 inches (1770 mm)

Height:

Approx. 57.9 inches (1470 mm)

Curb Weight Sti:

Approx. 3200-3300 lbs (1450-1500 kg)

Curb Weight Non Turbo:

Approx. 2900-3100 lbs (1315-1406 kg)

Sti Wheel Size:

17-inch alloy wheels

Sti Tire Size:

225/45R17

Wheel Bolt Pattern:

5x100

🛡️ Safety Features

NHTSA Front Impact Driver:

Good (for comparable 2005 models, specific STI ratings may vary)

NHTSA Front Impact Passenger:

Good (for comparable 2005 models)

IIHS Small Overlap Front:

Not Tested (as this test was not standard for 2005 vehicles)

ABS:

Standard Anti-lock Braking System

AWD:

Symmetrical All-Wheel Drive (enhances stability and traction)

Ebd:

Electronic Brake-force Distribution

Airbags:

Front airbags, side curtain airbags (availability may vary by trim).

Seatbelts:

Three-point seatbelts with pre-tensioners.

Child Seat Anchors:

LATCH (Lower Anchors and Tethers for CHildren) system.

💡 Technology Features

Audio System:

Factory AM/FM/CD player with premium speaker options available.

Display:

Basic LCD or LED displays for clock, radio information, and climate control.

Cruise Control:

Standard cruise control.

Traction Control:

Standard Traction Control System (TCS).

Aux Input:

May be present on later models or as an aftermarket addition.

🔧 Maintenance

Oil Change Interval:

Every 3,750 miles or 6 months, whichever comes first (severe driving conditions), or 7,500 miles/12 months (normal conditions). STI models may require more frequent changes due to performance driving.

Air Filter Replacement:

Every 15,000 miles or 12 months.

Spark Plug Replacement Sti:

Platinum-tipped: 60,000 miles. Iridium-tipped: 100,000 miles (check specific plug type).

Timing Belt Replacement:

Every 90,000 - 105,000 miles (critical maintenance item for EJ engines).

Engine Oil Capacity Sti:

Approx. 5.5 US quarts (5.2 liters) with filter (5W-30 or 10W-30 synthetic recommended).

Engine Oil Capacity Non Turbo:

Approx. 4.5 US quarts (4.3 liters) with filter (5W-30 or 10W-30 recommended).

Coolant Type:

Subaru Super Coolant (Blue) or equivalent ethylene glycol-based coolant.

Brake Fluid Type:

DOT 3 or DOT 4

Head Gasket Failure:

While less common in the EJ257 than earlier versions, head gasket leaks are a potential concern. Vigilant maintenance is key.

Ringland Failure Sti:

Can occur in heavily modified or aggressively driven STI engines due to increased cylinder pressures. Proper tuning and maintenance are crucial.

Clutch Wear:

Performance driving can accelerate clutch wear.

Rear Differential Noise:

Some owners report occasional noise from the rear differential, often related to fluid condition or wear.

📚 Vehicle History

Subaru Motorsports:

Deep roots in rallying, with the Impreza WRX STI being a homologation special for WRC competition.

Generations:

The 2005 model represents the GD chassis generation of the Impreza, specifically the 'Bugeye'/'Blobeye' update.

Sti Launch:

The STI variant, originally a rally homologation special, became a production model offering enhanced performance over the WRX.

Manufacturing Location:

Japan (Ota, Gunma Prefecture)

🏆 Awards & Recognition

Car And Driver Щения:

Often featured on Car and Driver's '10Best' lists for its class and performance capabilities.

Ralley Championships:

The Impreza platform, particularly the STI, has a rich history of World Rally Championship (WRC) victories.