Diagnosing Intermittents Using ECM Snapshots

The ECM snapshots may be very useful in diagnosing intermittent engine problems. You may retrieve and use the stored data in order to determine if a particular input was incorrect when the problem occurred. Many of the ECM DTC trouble charts will use the Freeze Frame information in order to pinpoint a problem if the problem is not current. For example. a vehicle comes in with an intermittent rough engine condition and a scan tool Snapshot was taken while the engine was running rough. Several data parameters may be retrieved and an abnormal parameter be noted. The MAP sensor the ECT sensor the IAT sensor. and the Knock Sensor parameters may be compared to the normal values of those parameters and any values that are out of the normal range investigated. Also. the fuel injector pulse width or the spark advance may be retrieved. This may indicate a fueling or an ignition irregularity that should be investigated. While this method may result in increased diagnosis time. this method also results in less actual repair time and fewer service comebacks.