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.
SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSFORD1991AEROSTAR VAN CARGO EXTENDED, 4.0 X, AWDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETHEORY AND OPERATIONENGINE CONTROLS - THEORY & OPERATION
1991 Ford Aerostar Van Cargo Extended, 4.0 X, AWD
Engine Controls - Theory & Operation
1991 Ford Aerostar Van Cargo Extended, 4.0 X, AWDSECTION Engine Controls - Theory & Operation
- Introduction
- Computerized Engine Controls
- Input Devices
- Notes
- A/C Compressor Clutch Signal
- Air Charge Temperature (Act) Sensor
- Barometric Pressure (BP) Sensor
- Brake On-Off (Boo) Switch
- Clutch Engage Switch
- Coolant Temperature Sensor
- Crankshaft Sensor
- EGR Valve Position (EVP) Sensor
- Engine Coolant Temperature (ECT) Sensor
- Fuel Injection Pump Lever (FIPL) Sensor
- Heated Exhaust Gas Oxygen (HEGO) Sensor
- Manifold Absolute Pressure (Map) Sensor
- Mass Airflow (MAF) Sensor
- Neutral Gear Switch (NGS)
- Neutral Safety Switch (NSS)
- Power Steering (P/S) Pressure Switch
- Profile Ignition Pick-Up (Pip)
- Self-Test Output/Self-Test Input (STO/STI) Connectors
- Throttle Position Sensor (TPS)
- Variable Reluctance Sensor (VRS)
- Vehicle Speed Sensor (VSS)
- Output Signals
- Fuel Delivery
- Fuel Control (Gasoline Engines)
- Fuel Control (7.3L Diesel)
- Idle Speed (Gasoline Engines)
- Idle Speed (7.3L Diesel)
- Ignition Systems
- Emission Systems
- Air Injection System
- EGR System
- Evaporative Emission Control
- Positive Crankcase Ventilation (PCV)
- Self-Diagnostic System
- Miscellaneous Controls
RENDER: 1.0x
NO RELATED
Recommended Tools & Savings
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.