Results of Incorrect Operation

With too much EGR flow at idle, cruise, of cold operation, any of the following conditions may occur:
^ Engine stops after cold start.
^ Engine stops at idle after deceleration.
^ Vehicle surges during cruise.
^ Rough idle.
If the EGR valve should stay open all of the time, the engine may not idle.

Too little or NO EGR flow allows combustion temperatures to get too high during acceleration and load conditions. This could cause:
^ Spark knock (detonation).
^ Engine overheating.

NOTE:

a. For diagnosis of the EGR system, refer to correct EGR system
b. When performing an inspection of the EGR system, DO NOT connect exhausting shop air to the tailpipe of the vehicle. The vacuum created by the shop air could cause false EGR valve operation to occur.