Exhaust Gas Recirculation: Testing and Inspection

EGR Transducer Operation:

FUNCTIONAL TEST
Warm up engine and allow the engine to idle, in neutral, with the throttle closed for 70 seconds; then abruptly accelerate the engine to approximately 2000 RPM, but not over 3000 RPM. Visible movement of the EGR valve stem should occur during this operation. This can be determined by change in the relative position of the groove on the EGR valve stem. This operation should be repeated several times to confirm movement. Movement of the stem indicates that the control system is functioning correctly.

EGR Diagnosis:

DIAGNOSIS
***UPDATED BY TSB # 25-01-89 SEPT. 18, 1989







GAS FLOW TEST
If control system is functioning properly, the valve and passages may be checked for exhaust gas flow. Slowly apply vacuum directly to the EGR valve with the engine warm and idling in neutral. Idle speed should drop 150 RPM or more. Engine speed should start to drop when vacuum reaches 2.0 to 3.5 inches Hg. This reduction in idle speed confirms that exhaust gas recirculation is taking place. If the speed change does not occur, or is less than that specified, exhaust deposits in the EGR valve or intake manifold EGR passages are indicated.

EGR Solenoid Valve Test:

SOLENOID TEST