🏷️ Basic Information Identification Make: Subaru Model: Impreza Trim: WRX STI Year: 2004 Powertrain: Gasoline Codes Chassis Code: GDB 👋 Introduction Market Position Vehicle Segment: Performance Compact Sedan/Wagon Competitors 2004: Mitsubishi Lancer Evolution VIII, Ford Focus SVT, Volkswagen GTI Competitive Analysis Unique Selling Proposition: Symmetrical All-Wheel Drive, turbocharged boxer engine, rally heritage Key Features Performance Focus: Engineered for high performance and handling, with a strong emphasis on driver engagement. Manual Value: Indispensable resource for owners and technicians seeking to maintain and repair the complex STI platform. 📋 Manual Details Coverage Areas Manual Type: Full Service Repair Manual Language: English Format: Digital (Likely PDF, though not explicitly stated, common for comprehensive manuals) Page Count Page Count Estimated: 1000+ 📖 Manual Coverage Systems Covered Engine: Engine mechanical, lubrication, cooling, fuel injection, ignition, emissions control, turbocharger system Transmission: Manual transmission (6-speed), clutch, driveline, limited-slip differentials (front, center, rear) Brakes: Front and rear disc brakes (Brembo calipers standard on STI), ABS, brake hydraulics, parking brake Suspension: Front MacPherson struts, rear multi-link independent suspension, springs, dampers, sway bars, alignment specifications Steering: Power assisted rack and pinion steering, steering column, tie rods Electrical: Battery, charging system, starting system, lighting, instrumentation, audio system, immobilizer, ECU wiring diagrams Body: Body panels, doors, hood, trunk, bumpers, interior trim, glass, locks, hinges HVAC: Heating, ventilation, air conditioning system, refrigerant, controls Diagnostics: OBD-II diagnostics, trouble codes, sensor data interpretation, testing procedures Procedures Included Maintenance: Routine maintenance, oil changes, filter replacements, fluid checks and changes, belt inspection and replacement, spark plug replacement Repair: Engine component replacement (pistons, rods, valves), turbocharger rebuild, transmission overhaul, brake caliper replacement, suspension component replacement, electrical component repair Troubleshooting: Step-by-step diagnostic procedures for common and uncommon faults, electrical circuit tracing, mechanical system diagnosis Installation: Component installation and removal, accessory fitting, timing belt installation Technical Depth Depth Level: Comprehensive (from basic maintenance to complete engine and transmission rebuilds) Diagnostic Complexity: Advanced diagnostic routines, including oscilloscope interpretation and component testing Wiring Diagrams: Detailed and specific wiring schematics for all major systems 📊 Manual Specifications File Format File Type: Likely PDF (Adobe Acrobat Reader compatible) Searchability: Typically includes text-searchable functionality for quick information retrieval Printability: Printable pages for on-the-go reference Print Quality Image Resolution: High-resolution images and diagrams for clarity Binding Type Binding: N/A (Digital Format) Paper Type Paper Quality: N/A (Digital Format) ⚙️ Engine Specifications Primary Engine Engine Code: EJ257 Engine Type: 2.5L DOHC 16-valve turbocharged horizontally opposed (boxer) 4-cylinder Performance Horsepower: 300 hp @ 6000 rpm (SAE Net) Torque: 300 lb-ft @ 3500 rpm (SAE Net) Redline: 7000 rpm Fuel System Fuel Type: Premium Unleaded Gasoline (91 octane or higher recommended) Fuel Delivery: Sequential multi-point fuel injection with electronic throttle control Turbocharger: IHI VF39 Ball Bearing Turbocharger with Top-Mount Intercooler Engine Management ECU Type: Denso ECU (specific part number for reference in manual) 🔧 Transmission Standard Transmission Type: 6-speed Manual Transmission Optional Optional Transmission: N/A for STI trim Features Drivetrain: Subaru Symmetrical All-Wheel Drive with Driver Controlled Center Differential (DCCD) Differential Type: Front Helical LSD, Rear Mechanical LSD, DCCD (center) Fluid Specs Transmission Fluid Type: Subaru Extra S (or equivalent API GL-5, 75W-90 synthetic) 📐 Dimensions Exterior Wheelbase: 100.0 inches Length: 173.8 inches Width: 70.1 inches Height: 56.3 inches Weights Curb Weight: 3285 lbs Wheels Tires Wheel Size: 17x8.0 inches Tire Size: 225/45R17 Bolt Pattern: 5x100 mm 🛡️ Safety Features Ratings NHTSA Front Crash Rating: 4 Stars NHTSA Side Crash Rating: 4 Stars IIHS Frontal Offset Rating: Good Active Features ABS: Standard Anti-lock Braking System AWD: Standard Symmetrical All-Wheel Drive Passive Features Airbags: Front dual-stage airbags, front side-impact airbags Seatbelts: Three-point seatbelts with pretensioners and load limiters 💡 Technology Features Infotainment Audio System: Factory AM/FM/CD player with 6 speakers (upgrade options available) Driver Assistance Traction Control: Standard Advanced Traction Control System (ATCS) integrated with AWD and DCCD. Connectivity Immobilizer: Factory immobilizer system for anti-theft protection. 🔧 Maintenance Service Intervals Oil Change Interval: Every 3,750 miles or 3 months (severe duty) / 7,500 miles or 6 months (normal duty) Timing Belt Replacement Interval: 105,000 miles or 7 years (critical for EJ257 engine) Fluid Specifications Engine Oil Type: 0W-30 or 5W-30 Synthetic (API SN or higher, ILSAC GF-5 or higher recommended) Engine Oil Capacity: 4.8 US quarts (with filter change) Coolant Type: Subaru Super Coolant (Blue) or equivalent Phosphate-Free Long Life Coolant Known Issues Piston Ringland Failure: Common issue with EJ257 engines under aggressive tuning or sustained high loads; manual provides diagnostic and repair procedures. Clutch Wear: Due to performance nature, clutch longevity can be impacted; manual covers clutch inspection and replacement. Turbocharger Failure: Improper break-in or lack of oil changes can lead to turbo issues; manual details inspection and rebuilds. 📚 Vehicle History Brand Heritage Subaru Rally Connection: Direct lineage from Subaru's successful World Rally Championship campaigns, influencing the STI's performance tuning. Model Evolution Gc8 To Gd Platform: This model...