Positioning:
The 2006 Impreza WRX STI represents the pinnacle of Subaru's rally-bred performance in the compact segment, targeting enthusiasts seeking a potent AWD platform with exceptional handling.
Competitors:
Competes directly with performance variants like the Mitsubishi Lancer Evolution, Honda Civic Type R, and Volkswagen Golf GTI of its era.
Performance Focus:
Emphasis on turbocharged power, advanced all-wheel drive, and track-tuned suspension.
Rally Heritage:
Direct lineage from Subaru's successful World Rally Championship (WRC) efforts.
Engine:
Comprehensive coverage of the EJ257 engine (2.5L Turbocharged Boxer)
Transmission:
6-speed manual transmission (TY856) repair and maintenance
Drivetrain:
All-Wheel Drive (AWD) system, differentials (front, center, rear), DCCD (Driver Controlled Center Differential) operation and adjustment
Suspension:
Front MacPherson strut, rear multi-link suspension, springs, dampers, bushings, alignment specifications
Brakes:
Front Brembo 4-piston calipers, rear Brembo 2-piston calipers, ABS system, brake fluid specifications and bleeding procedures
Electrical:
Wiring diagrams, component locations, diagnostic procedures for ECUs, sensors, lighting, audio, and HVAC
Body:
Body panel repair, collision repair, door, hood, trunk, glass, and trim component service
Routine Maintenance:
Oil changes, filter replacements, spark plug service, fluid checks and replacements
Troubleshooting:
Diagnostic flowcharts, common fault codes, symptom-based troubleshooting for engine, transmission, and electrical systems
Engine Repair:
Engine assembly/disassembly, cylinder head service, piston and connecting rod installation, crankshaft bearing replacement
Transmission Repair:
Transmission disassembly, gear inspection and replacement, clutch service, driveshaft and CV joint service
Suspension Steering:
Strut and shock absorber replacement, control arm bush replacement, steering rack overhaul, wheel bearing replacement
Brake System Repair:
Brake pad and rotor replacement, caliper service, brake line repair, ABS sensor diagnostics
Electrical Diagnostics:
ECM/PCM diagnostic strategies, sensor testing, actuator testing, CAN bus communication troubleshooting
Depth:
Comprehensive, covering everything from basic maintenance to complete engine and transmission rebuilds
Engine Type:
2.5L (2457cc) DOHC 16-valve turbocharged boxer-four
Horsepower:
300 hp @ 6000 rpm (USDM)
Torque:
290 lb-ft @ 4000 rpm (USDM)
Fuel Delivery:
Multi-point fuel injection (MPI) with Denso 550cc fuel injectors
Turbocharger:
IHI VF37 twin-scroll turbocharger
Intercooler:
Top-mounted air-to-air intercooler
ECU:
Denso Engine Control Unit (ECU)
Type:
6-speed Manual Transmission
Availability:
Not applicable, manual transmission standard on WRX STI
Dccd:
Driver Controlled Center Differential (DCCD) for variable torque split
Transmission Fluid Spec:
Subaru Extra Syn Gear Oil (75W-90) or equivalent
Transfer Case Fluid Spec:
Subaru Extra Syn Gear Oil (75W-90) or equivalent
NHTSA Frontal Crash:
4/5 stars (Driver/Passenger)
NHTSA Side Impact:
4/5 stars (Front/Rear Passenger)
ABS:
Standard Anti-lock Braking System (ABS)
E Brake:
Electronic Brake Force Distribution (EBD)
AWD:
Symmetrical All-Wheel Drive (SAWD) with DCCD
Airbags:
Driver and front passenger airbags, front side-impact airbags
Seatbelts:
Pre-tensioner seatbelts with force limiters
Chassis:
Ring-shaped reinforcement frame
Oil Change:
Every 3,750 miles or 6 months, whichever comes first (severe duty)
Air Filter:
Replace every 15,000 miles or 12 months
Spark Plugs:
Replace every 30,000 miles (iridium)
Coolant Flush:
Every 30,000 miles or 24 months
Engine Oil Spec:
SAE 5W-30 (API SJ/SL or ILSAC GF-3)
Coolant Type:
Subaru Super Coolant (Blue)
Ring Land Failure:
Potential for ring land failure on pistons due to detonation, especially with aggressive tuning or poor fuel quality. Requires careful attention to engine management and detonation prevention.
Clutch Wear:
High-performance nature can lead to accelerated clutch wear with aggressive driving.
Turbo Failure:
IHI VF37 turbo can be susceptible to failure if oil starvation or excessive heat is present. Proper warm-up and cool-down procedures are critical.
Head Gasket Leaks:
While less common than on earlier EJ engines, can still occur, particularly if overheating incidents happen.
Rally Connection:
Subaru's long and successful history in the World Rally Championship (WRC) directly influences the WRX STI's development and design.
Generation:
This 2006 model is part of the second generation (GD chassis) Impreza, specifically the 'hawkeye' facelift introduced for 2006.
Performance Leap:
The STI variant marked a significant upgrade over the standard WRX with a larger engine, improved brakes, suspension, and the introduction of DCCD.
Manufacturing Location:
Japan
