Component Tests and General Diagnostics

Caution: If the engine or underhood compartment is to be cleaned with steam or high pressure detergent, the centrifugal filter fan should be masked off to prevent liquids from entering the pump.

Diagnosis:
Air flowing to the exhaust ports at wrong times can cause a false lean O2S indication and cause the control module to add extra fuel. This will result in increased catalytic converter temperatures, because more fuel and air will be oxidizing in the converter.

The AIR system is NOT completely noiseless. Under normal conditions, noise rises in pitch as engine speed increases.

If noise is caused by the AIR system, check for:

- A seized AIR pump.
- Proper mounting and bolt torque of pump.
- Proper routing and connections of hoses.
- Replace pump if there is excessive noise.