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: Description
The air injection system is used to reduce hydrocarbon (HC) and carbon monoxide (CO) emissions. The system adds a controlled amount of fresh air to exhaust gases at the exhaust ports causing oxidation of gases. On all models except Federal 320i, air injection is used in conjunction with a thermal reactor. See Fig 1. The air injection system consists of a belt-driven air pump, a diverter valve, a check valve, electromagnetic switch (Blue), speed relay switch (also used by EGR system), and various connecting hoses and pipes.
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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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