Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSMERCURY1991TRACER BASE, 4D SEDAN, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 66 (ENGINE CONTROLS - SYSTEM/COMPONENT TESTS - EEC-IV (4.6L))
1991 Mercury Tracer Base, 4D Sedan, Automatic
Section 66 (Engine Controls - System/Component Tests - EEC-IV (4.6L))
1991 Mercury Tracer Base, 4D Sedan, AutomaticSECTION Section 66 (Engine Controls - System/Component Tests - EEC-IV (4.6L))
WARNING: This page is about a different car, the 1994 Mercury Grand Marquis, 1994 Lincoln Town Car, 1994 Lincoln Mark VIII, and 1994 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.
- Introduction
- Air Induction Systems
- Computerized Engine Controls
- Engine Sensors & Switches
- Notes
- A/C Cutout
- Barometric Pressure (BARO) Sensor
- Cylinder Identification (CID)
- Engine Coolant Temperature (ECT) Sensor
- EGR Atmospheric (EGRA) Solenoid
- EGR Position (EGRP) Sensor
- EGR Vacuum Regulator (EVR) Solenoid
- EGR Vacuum (EGRV) Solenoid
- EGR Valve Position (EVP) Sensor
- Heated Gas Oxygen Sensor (Ho2S)
- Inertia Fuel Shutoff (Ifs) Switch
- Intake Air Temperature (IAT) Sensor
- Knock Sensor (KS)
- Mass Airflow (MAF) Sensor
- Power Steering Pressure Switch (PSPS)
- Pressure Feedback (PFE) EGR Sensor & Diff PFE (DPFE) Sensor
- Throttle Position (TP) Sensor
- Vehicle Speed Sensor (VSS)
- Modules, Relays & Solenoids
- Fuel Systems
- Idle Control System
- Ignition System
- Emission Systems & Sub-Systems
- Wiring Diagrams
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.