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.
VAC - Vacuum (Differential Pressure) Sensor
1987 Pontiac Firebird V8-350 5.7LSECTION VAC - Vacuum (Differential Pressure) Sensor
Indicates voltage through vacuum sensor. Voltage reading is low when vacuum is low and increases as vacuum increases. With ignition on and engine stopped, reading should be under 1 volt, and with engine idling (high vacuum) reading should be over 3 volts.
Comparison of sensor readings with readings from known good sensor can be used to isolate malfunctioning sensor. Sensors have a color code tab in the connector cavity, and sensors with the same colored tab have identical calibration. Readings from sensors with like identification tabs should be the same to within +/-.4 volt.
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.