2004 SUBARU IMPREZA WRX sti Service Repair Manual

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🏷️ Basic Information Identification Make: Subaru Model: Impreza WRX STI Year: 2004 Codes Chassis Code: GDB Engine Code Primary: EJ257 Trim Level: STI 👋 Introduction Market Position Positioning: Performance sedan/coupe,...

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Sku: 394369

Tags: 2004 Car Cars IMPREZA WRX sti Misc Subaru

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Description

🏷️ Basic Information

Identification

Make:

Subaru

Model:

Impreza WRX STI

Year:

Codes

Chassis Code:

Engine Code Primary:

EJ257

Trim Level:

👋 Introduction

Market Position

Positioning:

Performance sedan/coupe, rally-bred homologation special, enthusiast vehicle.

Competitive Analysis

Competitors:

Mitsubishi Lancer Evolution, Subaru WRX (non-STI variants), Ford Focus RS, VW Golf R.

Key Features

Performance Focus:

Turbocharged Boxer engine, Symmetrical All-Wheel Drive, advanced differential systems.

Driving Dynamics:

Legendary handling, driver-focused cockpit, responsive steering.

Manual Value

Target Audience:

Enthusiast owners, independent repair shops, performance tuners.

Distinctiveness:

Provides dealership-level technical data not typically available to the public.

📋 Manual Details

Coverage Areas

Primary Coverage:

Vehicle Service and Repair

Secondary Coverage:

Diagnostics, Troubleshooting, Maintenance, Overhaul

Page Count

Estimated Pages:

2000+

Manual Type

Type:

Factory Service Manual / Workshop Manual

Language

Language:

English

Format

Format:

📖 Manual Coverage

Systems Covered

Engine Mechanical:

Complete overhaul, component replacement (pistons, rods, crankshaft, valves, camshafts), timing belt/chain system, lubrication system, cooling system.

Engine Management:

ECU diagnostics, fuel injection system, ignition system, emission control systems (catalytic converter, EGR, secondary air injection), sensors and actuators.

Transmission Manual:

Driveshaft, differential, gearbox overhaul, clutch replacement, shift linkage.

Transmission Automatic:

Not applicable for this STI model.

Drivetrain AWD:

Center differential, viscous coupling, rear differential, hub assemblies, CV joints.

Suspension:

Front and rear suspension components (struts, springs, control arms, bushings, sway bars), alignment specifications.

Brakes:

Brake system hydraulics, ABS system, rotor and pad replacement, caliper overhaul, brake bleeding procedures.

Steering:

Power steering system, steering rack, tie rods, wheel alignment.

Electrical System:

Battery, charging system, starting system, lighting, instrumentation, power windows, locks, HVAC controls, audio system.

Body And Interior:

Body panel removal and installation, door mechanisms, interior trim, seats, dashboard components, glass replacement.

HVAC:

Air conditioning system, heating system, blower motor, climate controls, refrigerant handling.

Procedures Included

Maintenance:

Oil changes, filter replacements, spark plug replacement, fluid checks and changes, brake inspections.

Troubleshooting:

Diagnostic flowcharts for common issues, symptom-based problem diagnosis.

Repair:

Step-by-step instructions for component replacement, system repair, and adjustments.

Diagnostics:

OBD-II diagnostic trouble codes (DTCs), sensor data interpretation, scan tool usage.

Rebuilds:

Detailed procedures for engine and transmission rebuilding, including torque specifications and clearances.

Wiring Diagrams:

Comprehensive electrical schematics for all vehicle systems.

Technical Depth

Depth:

Expert level, suitable for professional technicians and advanced DIY enthusiasts.

Scope:

Full vehicle service and repair, from routine maintenance to complete engine rebuilds.

📊 Manual Specifications

File Format

Format:

Searchability:

Searchable text content

Printability:

Printable pages

Print Quality

Quality:

High-resolution scans for clear text and diagrams

Binding Type

Binding:

N/A (Digital PDF)

Paper Type

Paper Type:

N/A (Digital PDF)

⚙️ Engine Specifications

Primary Engine

Engine Type:

Horizontally Opposed Turbocharged (Boxer)

Displacement:

2.5 Liters (2457 cc)

Engine Code:

EJ257

Performance

Horsepower Est:

300 hp @ 6000 rpm (SAE Net)

Torque Est:

300 lb-ft @ 4000 rpm (SAE Net)

Fuel System

Fuel Delivery:

Multi-point Fuel Injection (MPI), Electronic Throttle Control (ETC)

Turbocharger:

IHI VF30 (or similar depending on market), Intercooled

Engine Components

Cylinder Head:

Dual Overhead Camshaft (DOHC), 16 valves

Compression Ratio:

8.0:1

Fluid Specifications

Oil Type:

SAE 5W-30 Synthetic (API SG or SH)

Oil Capacity:

4.5 US quarts (4.3 L) with filter

Coolant Type:

Subaru Super Coolant (Blue)

🔧 Transmission

Standard

Transmission Type:

6-Speed Manual Transmission

Features

Driver Control:

Driver Controlled Center Differential (DCCD) with automatic and manual modes.

Fluid Type:

GL-5 75W-90 Gear Oil (Transmission and Front Differential)

Gear Ratios Primary

1St Gear:

3.636

2Nd Gear:

2.063

3Rd Gear:

1.448

4Th Gear:

1.094

5Th Gear:

0.970

6Th Gear:

0.777

Reverse:

3.545

Final Drive:

3.545

Drivetrain Spec

AWD System:

Symmetrical All-Wheel Drive with DCCD and Helical Front/Limited Slip Rear Differentials.

📐 Dimensions

Exterior

Length:

173.8 in (4415 mm)

Width:

69.7 in (1770 mm)

Height:

56.1 in (1425 mm)

Wheelbase:

103.0 in (2615 mm)

Front Track:

60.0 in (1525 mm)

Rear Track:

59.4 in (1510 mm)

Weights

Curb Weight Est:

3329 lbs (1510 kg)

Gross Weight Rating Est:

4343 lbs (1970 kg)

Wheel And Tire

Wheel Size:

17 x 8.0 inches

Bolt Pattern:

5 x 100 mm

Tire Size Std:

225/45R17

Fuel Capacity

Fuel Tank Capacity:

15.6 US gallons (59 L)

🛡️ Safety Features

Ratings

NHTSA Front Crash Rating:

4/5 Stars (Driver/Passenger)

NHTSA Side Impact Rating:

4/5 Stars (Front/Rear Passenger)

IIHS Crashworthiness:

Good (Frontal Offset)

Active Features

Standard Anti-lock Braking System (ABS) with Electronic Brakeforce Distribution (EBD).

Traction Control:

Standard Traction Control System (TCS) and Vehicle Stability Control (VDC).

Passive Features

Airbags Front:

Driver and front passenger airbags

Airbags Side:

Optional front side-impact airbags (market dependent)

Seatbelts:

3-point seatbelts with pretensioners and load limiters.

Body Structure:

Reinforced unibody construction with front and rear crumple zones.

💡 Technology Features

Infotainment

Head Unit:

Factory AM/FM/CD player, optional premium audio system.

Display:

Basic digital display for clock, temperature, and audio information.

Driver Assistance

Cruise Control:

Standard electronic cruise control.

Dccd:

Driver Controlled Center Differential provides advanced AWD torque management.

Connectivity

Bluetooth:

Not standard, aftermarket integration common.

Instrumentation

Gauge Cluster:

Includes tachometer, speedometer, fuel gauge, coolant temperature gauge, and multi-function display.

Boost Gauge:

Integrated factory boost gauge in the center console or dashboard.

🔧 Maintenance

Service Intervals

Oil Change Interval:

Every 3,750 miles (6,000 km) or 6 months, whichever comes first (under severe driving conditions).

Engine Air Filter:

Inspect every 15,000 miles (24,000 km), replace as needed.

Cabin Air Filter:

Replace every 15,000 miles (24,000 km) or 12 months.

Spark Plugs:

Iridium type: 105,000 miles (168,000 km).

Timing Belt:

Not applicable. Uses a timing chain.

Coolant Flush:

Every 30,000 miles (48,000 km) or 24 months.

Transmission Fluid Change:

Every 30,000 miles (48,000 km) or 24 months (for performance use).

Fluid Specifications

Brake Fluid Type:

DOT 3 or DOT 4

Power Steering Fluid Type:

Subaru Genuine ATF-HP or Dexron III compatible

Differential Fluid Type:

GL-5 75W-90 Gear Oil (Front and Rear)

Known Issues

Head Gaskets:

Less prone to failure than earlier EJ series engines, but still a potential concern under high heat/stress.

Ringland Failure:

Common issue on EJ257 engines, especially if modified or run with improper fueling/tuning, leading to piston ringland damage.

Clutch Wear:

Can wear prematurely with aggressive driving or repeated launches.

Turbocharger Failure:

Can occur due to lack of oil changes or improper warm-up/cool-down procedures.

📚 Vehicle History

Brand Heritage

Subaru Rally:

Strong lineage from Subaru's extensive World Rally Championship (WRC) success.

Model Evolution

Generation:

Second Generation Impreza (GD/GG) - Introduced 2000, facelifted in 2002 and 2005.

Gdb Sti Introduction:

The 2004 model year marked the introduction of the GDB chassis STI to the North American market.

Production

Manufacturing Location:

Gunma Prefecture, Japan

Production Years:

2004-2007 (for this specific chassis generation STI variant)

🏆 Awards & Recognition

Recognitions

Car And Driver 10Best:

The Impreza WRX (non-STI) was a frequent recipient of Car and Driver's 10Best list, highlighting its performance-to-value ratio.

Sports Car International World Performance Car:

The STI variant received accolades for its rally-bred performance and handling capabilities.

Ratings

Jdpowers Initial Quality:

Generally average to below average for initial quality during its production years, typical for performance vehicles.

Certifications

Emissions Standards:

Compliant with EPA and CARB emissions standards for its model year.