Positioning:
The 2004 Subaru Impreza WRX STI (also known as GDB) is a rally-bred, turbocharged performance sedan, a homologation special designed for motorsport. It is positioned as a premium, high-performance compact car.
Competitors:
Competes with other performance-oriented compacts of its era, such as the Mitsubishi Lancer Evolution, Volkswagen Golf GTI, and Ford Focus RS.
Performance Highlights:
Symmetrical All-Wheel Drive (AWD), turbocharged boxer engine, advanced differential systems, potent braking, and a driver-focused chassis.
Manual Purpose:
Provides authoritative, in-depth technical information for accurate diagnosis, repair, and maintenance, crucial for preserving the performance and longevity of this specialized vehicle.
Powertrain:
Engine, Transmission, Drivetrain, Fuel System, Exhaust System.
Chassis:
Suspension (front and rear), Steering System, Braking System, Wheels and Tires.
Electrical:
Wiring Diagrams, Ignition System, Starting System, Charging System, Lighting, Instrumentation, ECUs.
Body And Interior:
Body Panels, Doors, Windows, Seats, Trim, HVAC System, Restraint Systems (Airbags).
Maintenance:
Scheduled maintenance, oil changes, filter replacements, fluid checks and top-offs.
Diagnostics:
Troubleshooting guides, diagnostic trouble codes (DTCs) interpretation, component testing.
Repair And Rebuild:
Step-by-step repair procedures for major components (engine, transmission, suspension, brakes).
Adjustments:
Valve clearance adjustments, clutch adjustments, alignment procedures.
Depth:
Detailed diagnostic procedures, component removal and installation, specifications, tolerances, and torque values for most repairs.
Engine Type:
Horizontally Opposed (Boxer), Turbocharged, Intercooled
Displacement:
2.0 Liters (1994 cc)
Horsepower Ps:
265 PS (approx. 261 hp)
Torque Nm:
343 Nm (approx. 253 lb-ft)
Injection Type:
Multi-Point Fuel Injection (MPI), Electronic Fuel Injection (EFI)
Fuel Type:
Premium Unleaded Gasoline (98 RON recommended)
Crankshaft:
Cross-plane, forged
Coolant Type:
Subaru Super Coolant or equivalent (Ethylene Glycol based)
Transmission Type:
6-Speed Manual Transmission
Optional Transmission:
N/A (Manual transmission only for STI)
Drivetrain:
Symmetrical All-Wheel Drive (AWD) with Driver-Controlled Center Differential (DCCD)
Differentials:
Front: Helical LSD, Rear: Viscous LSD
Transmission Fluid Type:
API GL-5, SAE 75W-90 (manual gearbox); Subaru Extra LPS Fluid (transfer case/rear diff, if applicable)
NHTSA Front Impact:
Not rated (historical data may vary)
IIHS Front Impact:
Good (for 2004 model year Impreza range, STI specific rating may differ)
ABS:
Standard (4-wheel ABS)
Traction Control:
Standard (Symmetrical AWD, DCCD)
Airbags:
Driver and Front Passenger Airbags
Seatbelts:
3-point front and rear seatbelts with pretensioners
Body Structure:
Reinforced chassis with crumple zones and energy-absorbing structure.
Audio System:
Factory AM/FM/CD stereo system with basic speaker configuration. Aftermarket upgrades are common.
Stability Control:
Not equipped with Electronic Stability Control (ESC) in the modern sense; relies on AWD and differential systems for stability.
Auxiliary Input:
Typically no auxiliary input; older models may have tape decks or limited CD functionality.
Dashboard Features:
Driver-focused layout with tachometer, speedometer, boost gauge, oil pressure, and temperature gauges.
Oil Change Interval Km:
Every 5,000 km or 6 months (severe use), 7,500-10,000 km or 12 months (normal use)
Spark Plug Replacement Km:
100,000 km (Iridium type)
Timing Belt Replacement Km:
105,000 km or 7 years (whichever comes first)
Engine Oil Type:
API SG/SH/SJ/SL/SM, ACEA A3/B3 or A3/B4, Viscosity: 0W-30, 5W-30, 5W-40, 10W-30, 10W-40 (refer to manual for specific conditions)
Engine Oil Capacity Liters:
4.2 L (without filter), 4.5 L (with filter)
Coolant Capacity Liters:
7.5 L
Brake Fluid Type:
DOT 3 or DOT 4
Engine Reliability:
EJ207 engine is robust but susceptible to ringland failure if consistently abused or poorly tuned. Regular maintenance is critical. Head gasket failures can occur with age/heat cycles.
Transmission Wear:
The 6-speed transmission is strong, but clutch wear is expected with spirited driving. Synchro wear can occur on high-mileage units.
Suspension Components:
Worn suspension bushings (control arms, sway bars) are common due to spirited driving and age. Wheel bearings can also wear.
Electronics:
Intermittent issues with sensors (e.g., MAF, O2) and wiring harnesses can arise due to heat and vibration.
Subaru Rally Heritage:
Subaru's deep roots in World Rally Championship (WRC) with legendary drivers like Colin McRae and Petter Solberg heavily influenced the development and performance of the Impreza STI.
Gdb Generation:
This 2004 model represents the later part of the 'GDB' (second generation) Impreza, known for significant chassis and engine improvements over earlier versions.
Manufacturing Location:
Japan
Key Market:
Homologation special primarily for European and Japanese markets, with limited availability in North America for specific model years.
Performance Awards:
Consistently recognized in automotive press for its performance, handling, and rally-inspired driving dynamics.
Enthusiast Ratings:
Highly regarded by enthusiasts for its raw performance, tuner-friendliness, and motorsport pedigree.
Manual Endorsement:
This workshop manual is essential for any owner or technician seeking to maintain or repair the 2004 Subaru Impreza WRX STI to factory specifications.
