Air Injection: Description and Operation

Typical Managed Air Thermactor System:

The Managed Air Thermactor System is utilized in electronic control systems to divert thermactor air either upstream to the exhaust manifold check valve or downstream to the rear section check valve and dual bed catalyst. The system will also dump thermactor air to atmosphere during some operating modes. An air control valve is used to direct the air either upstream or downstream. An air bypass valve is used to dump air to atmosphere. This system is used with a three-way catalyst and can be electronically or non-electronically controlled. The operation of air is as follows:
1. The air is dumped or bypassed to atmosphere when the exhaust is rich. This prevents backfire and catalyst damage along with removing the pump load from the engine.
2. The air is sent upstream (to exhaust manifold) when the engine is first started and the catalyst is still cold.
3. The air is sent downstream (to catalyst) after the engine and catalyst are warmed up.