Exhaust Gas Recirculation (EGR) System Diagnosis for Oldsmobile Alero 1999
Results Of Incorrect Operation
With too much EGR flow at idle, cruise, or cold operation, any of the
following conditions may occur:
| • | The engine stops after a cold start. |
| • | The engine stops at idle after deceleration. |
| • | The vehicle surges during cruise. |
| • | The vehicle idles roughly. |
If the EGR valve stays open all of the time, the engine may not idle.
A DTC P0401 may set. Refer to
DTC P0401 Exhaust Gas Recirculation (EGR) Flow Insufficient
.
Too little or no EGR flow allows the combustion temperatures to get
too high during acceleration and load conditions. This could cause the following
conditions:
| • | Spark knock (detonation) |
