🏷️ Basic Information Identification Make: Porsche Model: 928 S4 Year: 1991 Generation Generation Name: Third Generation (1987-1991) Generation Code: Series 4 Codes Chassis Code: 928 👋 Introduction Market Position Market Segment: Luxury Grand Tourer (GT), High-Performance Sports Car. Competitors 1991: Ferrari 412, Aston Martin Virage, Jaguar XJ-S, Chevrolet Corvette ZR-1. Key Features Design Philosophy: Front-engine, rear-wheel-drive layout for optimal weight distribution, advanced aerodynamics, luxury appointments. Unique Selling Proposition: V8 power, transaxle layout for balanced handling, distinctive coupe styling, Porsche engineering and prestige. 📋 Manual Details Coverage Areas Manual Type: Owner's Manual Language: English Format: Printed Booklet Page Count Page Count: Approximately 250-300 pages (typical for this era/model) 📖 Manual Coverage Systems Covered Powertrain: Engine operation, cooling system, fuel system, ignition system, exhaust system. Drivetrain: Transmission operation (automatic), drive shafts, differential. Chassis: Braking system, steering system, suspension system (front and rear), wheel and tire information. Electrical: Lighting systems, dashboard indicators and warnings, fuses, basic electrical component operation (radio, wipers, etc.). Body And Interior: Doors, windows, seats, climate control, dashboard layout, interior features, locking mechanisms. Safety Features: Seat belts, airbags (if equipped, though less common in 1991), child safety features. Procedures Included Operation: Starting and stopping the engine, driving instructions, gear selection, use of controls. Maintenance: Checking fluid levels (oil, coolant, brake fluid, power steering fluid), tire pressure checks, basic cleaning procedures. Troubleshooting: Explanation of dashboard warning lights, basic troubleshooting for common minor issues. Emergency: Information on emergency procedures, spare tire and jack location and usage. Technical Depth Depth Level: Owner-level understanding and basic operational guidance. Focuses on safe and correct usage, not detailed repair procedures. 📊 Manual Specifications File Format Digital Format: PDF (if scanned/digitized) Print Quality Print Quality Description: Original factory print quality, typically good with clear diagrams and text. Binding Type Binding Type Description: Original perfect bound or stapled booklet. Paper Type Paper Type Description: Standard quality paper for owner's manuals of the era. ⚙️ Engine Specifications Primary Engine Engine Code: M64/01 (or similar variant for 1991 S4) Engine Type: V8, naturally aspirated Displacement: 5.0 Liters (4957 cc) Bore X Stroke: 97.0 mm x 84.0 mm Compression Ratio: 10.0:1 Valve Train: Dual Overhead Camshafts (DOHC), 4 valves per cylinder (32 valves total) Performance Horsepower Net: 320 bhp @ 6,000 rpm (approx.) Torque Net: 317 lb-ft @ 3,000 rpm (approx.) Fuel System Fuel Injection: Bosch Motronic M2.2 Fuel Type: Unleaded Premium Gasoline (91 octane or higher) Cooling System Coolant Type: Porsche specified coolant (typically propylene glycol based), 50/50 mix with distilled water. Coolant Capacity: Approximately 10.5 Liters (11.1 US Quarts) 🔧 Transmission Standard Transmission Type: 4-speed Automatic Transaxle (Tiptronic optional in later years, but 1991 likely standard auto) Optional Transmission Type: 5-speed Manual Transaxle (available, but less common than automatic for S4) Features Drive Layout: Rear-Wheel Drive (RWD) with rear transaxle configuration. Fluid Specifications Automatic Transmission Fluid Type: Porsche approved ATF (e.g., Mobil ATF 220 or equivalent specified by Porsche). Fluid Capacities Automatic Transmission Fluid Capacity: Approximately 8.0 Liters (8.5 US Quarts) for complete fill. 📐 Dimensions Exterior Length: 4650 mm (183.1 in) Width: 1780 mm (70.1 in) Height: 1280 mm (50.4 in) Wheelbase: 2500 mm (98.4 in) Front Track: 1520 mm (59.8 in) Rear Track: 1510 mm (59.4 in) Weights Curb Weight: Approximately 1540-1620 kg (3395-3571 lbs), depending on options. Gross Vehicle Weight Rating Gvwr: Approximately 2030 kg (4475 lbs) Towing Capacity: Not Recommended/Specified by Manufacturer. 🛡️ Safety Features Ratings Crash Test Ratings: No standardized crash test ratings (e.g., NHTSA/IIHS) were universally applied or readily available for this era of European luxury cars in the same way as modern vehicles. Active Features Braking System: Four-wheel disc brakes with internal ventilation. ABS (Anti-lock Braking System) standard. Suspension Features: Transaxle design contributes to balanced weight distribution. Independent suspension front and rear. Passive Features Seat Belts: Three-point inertia-reel seat belts with pretensioners (front), three-point belts (rear). Airbags: Driver's side airbag standard. Structural Integrity: Integrated safety cage, crumple zones. 💡 Technology Features Infotainment Audio System: Original Porsche (Blaupunkt or Becker) AM/FM Cassette stereo system, often with amplifier. CD changer might be an optional accessory. Climate Control Climate Control System: Automatic climate control (Thermatronic) standard on S4, with manual AC and heating. Driver Assistance Cruise Control: Standard. ABS: Standard (Anti-lock Braking System). Connectivity Connectivity Features: No modern connectivity features like Bluetooth or USB. Analog systems only. 🔧 Maintenance Service Intervals Oil Change Interval: Every 10,000 km (6,000 miles) or annually. Timing Belt Interval: Every 72,000 km (45,000 miles) or 5 years (critical for this engine to prevent catastrophic failure). Brake Fluid Flush: Every 2 years. Coolant Flush: Every 2 years. Fluid Specifications Engine Oil Type: API SG or higher, viscosity grade SAE 0W-40, 5W-40, 10W-40, or 5W-50 depending on climate. Porsche A40 approval is ideal. Engine Oil Capacity: Approximately 8.5 Liters (9.0 US Quarts) with filter change. Power Steering Fluid Type: Pentosin CHF 11S...