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.
Air Injection System: Operation
The injection of fresh air is delivered at the exhaust ports, the exhaust pipe, or the air cleaner; depending on engine and vehicle operating characteristics. Air is injected at exhaust ports when intake manifold vacuum is below 13.97 in. Hg, engine speed is below 1800 RPM, vehicle speed is under 35 MPH and OC temperature is below 1112°F (600°C).
Air is by-passed to air cleaner during deceleration and/or when intake manifold vacuum is below 13.97 in. Hg, engine speed is below 1800 RPM, and OC temperature is above 1445°F (785°C). Air is injected into exhaust pipe (ahead of OC) at all other times.
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.
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