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.
THERMACTOR System: Operation: Notes
Inlet air to air pump is drawn through a centrifugal air filter fan. Air pump then supplies air under pressure to exhaust port near exhaust valve, by either an external air manifold, or through an internal drilled passage in cylinder head or exhaust manifold. Oxygen in fresh air, plus heating of exhaust gasses, cause further burning which converts gasses into carbon dioxide and water.
In Managed Thermactor Air System, air can be by-passed to atmosphere by a Thermactor Air By-Pass Valve and/or directed upstream near exhaust manifold or downstream to underbody catalytic converter by Thermactor Air Control Valve. Some models may use a Combined Air By-Pass/Air Control Valve.
In Thermactor II System, natural pulses present in exhaust system are used to pull air into exhaust manifold through a Pulse Air Valve. Pulse air valve is connected to exhaust manifold with a tube and to air cleaner with a hose.
In Extended Idle Air By-Pass System, a normally closed Idle Tracking Switch opens when throttle returns to idle, signaling EEC Module to de-energize normally closed solenoid valve. Vacuum is removed from normally closed by-pass valve, causing thermactor secondary air to be dumped into atmosphere.
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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.