The 1990 Audi 100, part of the C3 generation, represents a significant era in German automotive engineering, renowned for its sophisticated design and robust construction. As an executive sedan and wagon, it competed with established luxury brands, offering a comfortable ride, advanced features for its time, and a distinct aerodynamic "tear drop" design. A key differentiator was the availability of the groundbreaking quattro all-wheel-drive system, underscoring Audi's commitment to performance and all-weather capability. This model exemplifies German engineering quality, focusing on durability and a refined driving experience for discerning owners. This comprehensive Factory Service Manual (FSM) is your authoritative guide to the service and repair of the 1990 Audi 100. With over 1500 pages of detailed information, it covers all major systems, including engine variants, manual and automatic transmissions, front-wheel and quattro drivetrains, suspension, brakes, steering, electrical systems, and climate control. The manual provides essential procedures for scheduled maintenance, diagnostics, component repair, and major component rebuilds, along with critical technical specifications like torque values and fluid capacities. It is an indispensable resource for owners, mechanics, and technicians aiming to maintain the optimal performance and longevity of their Audi 100. 🏷️ Basic Information Identification Make: Audi Model: 100 Year: 1990 Generation Code: C3 👋 Introduction Market Position Segment: Executive Sedan/Wagon Competitive Analysis Competitors: BMW 5 Series, Mercedes-Benz E-Class, Volvo 740/940 Key Features Design: Aerodynamic 'Tear Drop' Design, Audi Space Frame (ASF) precursor elements Drivetrain: Available quattro AWD system was a significant differentiator Engineering: German engineering, focus on build quality and comfort 📋 Manual Details Coverage Areas Primary Focus: Service and Repair Page Count Estimated Pages: 1500+ Manual Type Type: Factory Service Manual (FSM) Language Language: English Format Format: PDF Download 📖 Manual Coverage Systems Covered Engine: All Engine Variants (e.g., 2.3L 5-cylinder) Transmission: Manual and Automatic Transmissions Drivetrain: Front-Wheel Drive (FWD) and quattro All-Wheel Drive (AWD) Suspension: Front and Rear Suspension Systems Brakes: Brake System Components and Service Steering: Power Steering System Electrical: Complete Electrical Schematics and Component Testing Body And Chassis: Bodywork, Doors, Windows, and Chassis Climate Control: Heating, Ventilation, and Air Conditioning (HVAC) Fuel System: Fuel Injection System (CIS-E, KE-Jetronic) Exhaust System: Exhaust System Components and Repair Procedures Included Maintenance: Scheduled Maintenance, Fluid Changes, Filter Replacements Diagnostics: Troubleshooting Guides, Symptom-Based Diagnostics Repair: Component Removal, Disassembly, Assembly, and Installation Rebuilds: Engine, Transmission, and Major Component Rebuild Procedures Adjustments: Alignment, Valve Clearances, Fuel System Adjustments Specifications: Torque Specifications, Clearances, Fluid Capacities Technical Depth Depth: Comprehensive (from basic maintenance to complete engine rebuilds) 📊 Manual Specifications File Format Searchability: Likely Searchable Text (depending on PDF conversion quality) Print Quality Readability: High (designed for clarity and detail) Binding Type Binding: N/A (Digital PDF) Paper Type Paper: N/A (Digital PDF) ⚙️ Engine Specifications Primary Engine Engine Code: JN, NF, KU, AAN (example variants) Configuration: Inline 5-Cylinder (typically) Displacement: 2.3 Liters (2309 cc) Performance Horsepower: Approx. 130-140 hp (naturally aspirated), 165 hp (turbocharged 20v in later models/S4) Torque: Approx. 137-150 lb-ft Fuel System Injection Type: Bosch CIS-E (Continuous Injection System - Electronic) or KE-Jetronic Fuel Type: Unleaded Gasoline Ignition System System: Electronic Ignition 🔧 Transmission Standard Type: 5-Speed Manual Optional Type: 4-Speed Automatic (ZF 4HP22) Features Drivetrain Options: FWD or quattro AWD 📐 Dimensions Exterior Body Styles: 4-door Sedan, 5-door Avant (Wagon) Weights Curb Weight: Approx. 3,000-3,400 lbs (depending on configuration) 🛡️ Safety Features Ratings Crash Testing: NHTSA (US) and Euro NCAP (Europe) data may vary by model year and region Active Features ABS: Available Anti-lock Braking System (ABS) Passive Features Airbags: Driver Airbag (standard on most later models) Seatbelts: Front and Rear Seatbelts 💡 Technology Features Infotainment Audio System: Factory AM/FM Cassette Stereo System, often with premium options available. Driver Assistance ABS: ABS availability as mentioned in safety. Connectivity Features: Basic for its era; focus was on mechanical engineering and comfort, not extensive electronic connectivity. 🔧 Maintenance Service Intervals Oil Change: Typically every 5,000-7,500 miles or 6-12 months, consult manual for exact specification. Timing Belt: Crucial replacement interval, often around 60,000 miles or 5 years. **Extremely important for 5-cylinder engines.** Fluid Specifications Engine Oil: Typically 5W-40 or 10W-40 synthetic, refer to manual for specific viscosity and API rating. Coolant: G11 (Blue) or G12 (Red) Antifreeze/Coolant (check manual for correct type). Transmission Fluid Auto: Dexron III or equivalent automatic transmission fluid. Brake Fluid: DOT 3 or DOT 4 Brake Fluid. Known Issues Electrical System: Degradation of wiring insulation, failing dashboard components (e.g., VDO gauges), door lock actuators. Fuel System: CIS-E issues, failing fuel accumulators or pressure regulators, injector seal leaks. Engine: Timing belt failure (catastrophic), coolant leaks from plastic components, valve cover gasket leaks. Suspension: Worn ball joints, control arm bushings, and strut mounts. 📚 Vehicle History Brand Heritage Heritage: Audi, known for its pioneering spirit in quattro AWD and engineering. Model Evolution Generation: The 1990 model year falls within the C3 generation (1982-1994). Production...