General System Operation

The EGR valve is opened by vacuum to let exhaust has flow into the intake manifold. The exhaust gas then moves with the air/fuel mixture into the combustion chamber. If too much exhaust gas enters combustion will not occur. For this reason, very little exhaust gas is allowed to pass through the valve especially at idle. The EGR valve is usually open under the following condition:
- Warm engine operation
- Above idle speed