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.
1991 Infiniti Q45 aFACTORY OEM SERVICE PROCEDURE
Fuel Control: Notes
Fuel system is controlled by ECU based upon the following sensor input signals. If feedback system does not function properly, check input signals before replacing ECU.
- A/C Clutch Signal - Signal received from automatic A/C amplifier.
- Airflow Meter.
- Battery Voltage.
- Crank Angle Sensor.
- Engine (Coolant) Temperature.
- Exhaust Gas Temperature Sensor (Calif. models only).
- Ignition (START) Switch.
- Oxygen Sensor.
- Park/Neutral (Inhibitor) Switch - Signal received from P/N relay.
- Power Steering Pressure Switch.
- Secondary Throttle Sensor (traction control system equipped models only).
- Sub-Crank Angle Sensor.
- Throttle Position Sensor.
- Throttle (Idle) Switch.
- Vehicle Speed Sensor.
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.