Results of Incorrect Operation

TOO MUCH EGR
Too much Exhaust Gas Recirculation (EGR) flow tends to weaken combustion, causing the engine to run roughly or stop. With too much EGR flow at idle, cruise, or cold operation, any of the following conditions may happen:

^ 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 EGR
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.
^ Emission test failure.