🏷️ Basic Information Identification Make: Pontiac Model: Grand Prix Year: 1991 Generation Chassis Code: W-body Codes Engine Code Primary: LQ1 (3.4L V6) Engine Code Secondary: LG5 (3.1L V6) 👋 Introduction Market Position Positioning: A premium personal luxury coupe and sedan in its era, competing with models like Ford Thunderbird and Chevrolet Lumina/Monte Carlo. Competitive Analysis Competitors: Ford Thunderbird, Chevrolet Lumina, Chevrolet Monte Carlo, Chrysler LeBaron Coupe/Sedan. Key Features Design: Aerodynamic styling, often featuring pop-up headlights (on earlier W-bodies, but not typically the 1991 model), and a comfortable, often sporty interior. Powertrain Options: V6 engines, known for a balance of performance and refinement. Manual Benefit Diy Advantage: Enables owners to perform maintenance and repairs themselves, saving on labor costs and providing a deeper understanding of their vehicle. Diagnostic Value: Provides the same diagnostic trees and schematics used by professional technicians, allowing for accurate problem identification. 📋 Manual Details Coverage Areas All Models And Trims: Yes Repair Scope: A-Z, all repairs Page Count Estimated Page Count: Typically 1000+ pages for a complete factory service manual of this era. Manual Type Type: Factory Service Manual / Repair Manual Language Language: English Format Format: PDF File Compatibility: Windows (Vista32/64, XP, ME, 98, NT, 2000) and Mac compatible 📖 Manual Coverage Systems Covered Engine: Yes (including diagnostics, repair, rebuild) Fuel System: Yes (including fuel injection, pumps, lines, specifications) Emission Control: Yes (including emissions diagnosis and repair) Cooling System: Yes (radiator, water pump, thermostat, fan diagnostics) Lubrication System: Yes (oil pump, oil filter, oil specifications) Ignition System: Yes (spark plugs, coils, ignition control module) Charging System: Yes (alternator, battery, starter diagnostics) Automatic Transmission: Yes (including diagnosis, repair, fluid specifications) Manual Transmission: Yes (if equipped, including diagnosis, repair, fluid specifications) Drivetrain: Yes (transfer case, drive shafts, differentials) Suspension: Yes (front and rear suspension components, alignment) Steering: Yes (power steering system, steering column) Brakes: Yes (front/rear brakes, ABS if equipped, parking brake) Climate Control: Yes (air conditioning, heater, ventilation) Safety Systems: Yes (supplemental restraint system - airbags, seat belts) Body And Chassis: Yes (body panels, doors, glass, interior trim) Electrical System: Yes (comprehensive wiring schematics, components) Instrumentation: Yes (instrument cluster, gauges, warning lights) Accessories: Yes (cruise control, power locks, wipers/washers, horn, audio/visual systems) Procedures Included Maintenance: Yes (scheduled maintenance, fluid checks, filter replacements) Diagnostics: Yes (troubleshooting guides, symptom-based diagnosis) Repair: Yes (step-by-step repair procedures for all covered systems) Rebuilds: Yes (engine and transmission rebuild procedures) Adjustments: Yes (e.g., brake adjustments, clutch adjustments) Installation: Yes (e.g., component installation) Technical Depth Depth: Factory level, dealership technician quality Content Type: Detailed instructions, diagrams, illustrations, wiring schematics, specifications 📊 Manual Specifications File Format File Format: PDF Searchability: Likely searchable text-based PDF Print Quality Printability: Yes, all pages printable Image Enhancement: Yes, images can be blown up and printed enlarged Binding Type Binding Type: N/A (Digital PDF) Paper Type Paper Type: N/A (Digital PDF) ⚙️ Engine Specifications Primary Engine Engine Name Primary: 3.4L V6 (LQ1) Displacement Primary: 3.4 liters / 207 cubic inches Configuration Primary: Overhead Valve (OHV), 60-degree V6 Horsepower Primary: Approximately 160 hp @ 4700 rpm Torque Primary: Approximately 195 lb-ft @ 3200 rpm Secondary Engine Engine Name Secondary: 3.1L V6 (LG5) Displacement Secondary: 3.1 liters / 191 cubic inches Configuration Secondary: Overhead Valve (OHV), 60-degree V6 Horsepower Secondary: Approximately 135 hp @ 4400 rpm Torque Secondary: Approximately 170 lb-ft @ 2000 rpm Fuel System Fuel Delivery: Multi-port Fuel Injection (MPFI) Fuel Type: Unleaded gasoline 🔧 Transmission Standard Transmission Type: 4-speed automatic (THM-P320 / 4T60-E) Optional Manual Transmission: Not commonly available for this model year and specific trim, primarily automatic. Features Transmission Control: Electronic control for the 4T60-E transmission. Fluid Specifications Automatic Transmission Fluid: Dexron-III (or equivalent) ATF 📐 Dimensions Exterior Wheelbase: Approx. 107.5 inches Length: Approx. 196.7 inches Width: Approx. 70.9 inches Height: Approx. 53.4 inches (coupe) Weights Curb Weight Estimate: Approx. 3300-3500 lbs (depending on trim and options) Gross Vehicle Weight Rating: Typically around 4500 lbs. 🛡️ Safety Features Ratings NHTSA Ratings: Specific crash test data for 1991 models may be limited in public databases; refer to manual for internal testing or design considerations. Active Features ABS: Available on some trims, not standard. Passive Features Airbags: Driver-side airbag typically standard for 1991. Seat Belts: Front and rear seat belts, often with shoulder belts. 💡 Technology Features Infotainment Audio System: Factory AM/FM stereo with cassette player, often with optional premium sound systems. Driver Assistance Cruise Control: Standard or optional, electronically controlled. Connectivity Multiplex Communication: The manual lists 'Multiplex/Can Communication', indicating the presence of early multiplexed electrical systems, a precursor to modern CAN bus. 🔧 Maintenance Service Intervals Oil Change Interval: Typically every 3,000-5,000 miles or 3-6 months, depending on driving conditions. Consult manual for specific recommendations. Transmission Fluid Change: Recommended every 30,000-60,000 miles. Consult manual for exact interval and procedure. Spark Plug Replacement: Typically around 30,000-60,000 miles for conventional plugs,...