Chart C-7 EGR System Check - Port Fuel Injection

Chart C-7:

Chart C-7 Wiring Diagram:

CIRCUIT DESCRIPTION:

The EGR valve is operated by ported vacuum. This allows the exhaust gases to flow into the intake manifold. The exhaust gases then combines 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, none at idle. The amount of EGR is controlled by variations in vacuum and the EGR control solenoid.
The EGR valve is usually open under the following conditions:

^ Warm engine operation
^ Throttle off-idle

TEST DESCRIPTION:

1. This tests for a sticky EGR valve. If EGR valve is sticking, remove and inspect the valve to determine if it can be cleaned, or if it needs be replaced. A sticking EGR valve can cause a rough idle condition.

2. This checks for plugged EGR passages. If the passages are plugged, the engine may experience severe detonation on acceleration.