🏷️ Basic Information Identification Make: Audi Model: 100 / 100 Avant Year: 1991 Chassis Codes: 4A (Sedan), 4A2 (Sedan), 2A5 (Avant - likely an internal or variant code, 4A chassis generally applies to Avant as well) Market Segment: Executive/Mid-size Luxury 👋 Introduction Market Position Positioning: The Audi 100 (Typ 4A) represented Audi's entry into the more premium mid-size sedan and wagon segment, competing with established European luxury brands. Competitive Analysis Competitors: BMW 5 Series, Mercedes-Benz E-Class, Volvo 240/740/940 series, Saab 9000. Key Features Audi Advancements: Known for its aerodynamic styling, advanced Quattro all-wheel-drive system, and a focus on build quality and driver comfort. Manual Purpose Purpose: To provide technicians and knowledgeable owners with the precise factory-level repair and maintenance procedures for the 1991 Audi 100/Avant. 📋 Manual Details Coverage Areas Primary Coverage: All 1991 Audi 100 and 100 Avant models Repair Scope: Comprehensive A-Z, vehicle-specific Page Count Estimated Page Count: Likely 800-1200+ pages (typical for comprehensive dealer-level manuals of this era) Manual Type Type: Service and Repair Manual Language Language: English Format Format: Print 📖 Manual Coverage Systems Covered Engine: Engine mechanical, diagnostics, fuel injection, ignition, emissions, cooling, lubrication, timing Transmission: Manual and Automatic transmission overhaul, diagnostics, operation, fluids Drivetrain: Front-wheel drive, Quattro all-wheel drive system (differentials, driveshafts, hubs) Suspension: Front and rear suspension components, alignment, shocks, springs, bushings Brakes: Hydraulic system, ABS (if equipped), brake pads, rotors, calipers, lines, master cylinder Steering: Power steering system, steering rack, tie rods, column Electrical: Complete wiring diagrams, starter, alternator, battery, lighting, instruments, power windows, locks, mirrors, climate control electronics Body: Body panel removal/installation, interior trim, glass, seals, chassis components HVAC: Heating, Ventilation, and Air Conditioning system operation, diagnostics, component replacement Procedures Included Maintenance: Scheduled maintenance, fluid changes, filter replacements, tune-ups Diagnostics: Troubleshooting guides, symptom-based diagnostics, fault code interpretation (OBD I era) Repair: Component disassembly, reassembly, adjustment, and replacement for all systems Technical Specifications: Torque specifications, clearances, fluid capacities, electrical resistance values Technical Depth Depth: Dealer-level comprehensive, covering everything from routine maintenance to full engine and transmission rebuilds. Diagnostic Tools: Information on necessary special tools and diagnostic equipment for effective repair. 📊 Manual Specifications File Format Format: Printed Publication Print Quality Quality: High-quality, durable paper stock, clear diagrams and text. Binding Type Binding: Likely a sturdy comb or perfect binding, designed for workshop use. Paper Type Paper Quality: Durable, often coated paper to resist grease and workshop grime. ⚙️ Engine Specifications Primary Engine Engine Type: Inline 5-cylinder, naturally aspirated Displacement: 2.3 Liters (2309 cc) Bore X Stroke: 76.4 mm x 101.0 mm Compression Ratio: 10.0:1 (typical) Performance Horsepower: 130 PS (96 kW) @ 5,500 rpm (typical for the 2.3E) Torque: 182 Nm (134 lb-ft) @ 4,000 rpm (typical for the 2.3E) Fuel System Injection: Bosch KE-Jetronic CIS-E (CIS-Electronic Fuel Injection) Fuel Type: Unleaded Gasoline (Premium recommended) Engine Management Ignition: Electronic Ignition system (e.g., Digifant or similar) Emissions Control: Catalytic Converter, Lambda Sensor (O2 sensor), EGR (Exhaust Gas Recirculation) 🔧 Transmission Standard Standard Transmission: 5-speed Manual Optional Optional Transmission: 4-speed Automatic (ZF 4HP22) Features Drivetrain Options: Front-Wheel Drive (FWD) standard, Quattro All-Wheel Drive (AWD) optional on most models. Fluid Type Automatic Transmission Fluid: Dexron III or equivalent (refer to manual for specific Audi part number) Manual Transmission Fluid: Gear Oil GL-4 75W-90 or similar (refer to manual) Differential Fluid: API GL-5 75W-90 or similar (refer to manual) 📐 Dimensions Exterior Length: Approx. 4790 mm (Sedan) / 4817 mm (Avant) Width: Approx. 1778 mm Height: Approx. 1410 mm (Sedan) / 1450 mm (Avant) Wheelbase: Approx. 2760 mm Wheel Bolt Pattern: 5x112 Weights Curb Weight: Approx. 1450-1550 kg (depending on drivetrain and equipment) Gross Vehicle Weight: Refer to vehicle's VIN plate/sticker 🛡️ Safety Features Ratings Crash Test Era Context: Testing standards in 1991 were less stringent than today; specific NCAP ratings are unlikely to be readily available but the vehicle was designed with European safety standards of the time in mind. Active Features ABS: Anti-lock Braking System (ABS) often standard or optional on higher trims/Quattro models. Passive Features Airbags: Driver's airbag typically standard for 1991. Passenger airbag less common for this year/model. Seatbelts: Three-point inertia-reel seatbelts, height-adjustable front belts. Body Structure: Designed with crumple zones and a safety cage for occupant protection. 💡 Technology Features Infotainment Audio System: Factory-installed Audi sound systems, often with cassette player and AM/FM radio. Pre-wiring for CD changer might be present on later models. Driver Assistance ABS Implementation: ABS was a significant technology for its time, improving braking stability and reducing stopping distances under hard braking. Connectivity Pre Wiring: Limited by modern standards, but might have provisions for early cellular phones or aftermarket cruise control installations. Comfort Features Power Accessories: Power windows, power locks, and power mirrors were available, often standard on higher trims. 🔧 Maintenance Service Intervals Oil Change Interval: Typically every 10,000-15,000 km or 6-12 months (refer to manual...