Had a challenging one at work this week, an '08 Buick Lucerne 3.8L with a complaint of random stalling. One time in a parking lot, couple times while coming off the highway, all over the span of a month. Always restarts. No pattern to the symptom that the customer has noticed.
A symptom this infrequent is tough to diagnose, but it's worth trying. No codes, fuel trims are excellent at all load ranges. The throttle body was somewhat dirty, so I cleaned and relearned it.
Put 30-some miles on it yesterday, watching scan data, when I came to a stop and felt the engine try to stall. Finally! But just as quickly as it happened, the engine smoothed out and acted like nothing was wrong. Kept driving well for the rest of the day. *sigh* Figures.
Here's the data capture during the 'event'. As always, hit the Open PID List button on ScanShare to view the PIDs.
A few things stood out to me immediately, around frame 755. One was the ignition mode switching to 'bypass'. Another was the drop in Ignition 1 voltage. Another was the jump in engine load.
I wanted to bring this to the community for any thoughts or theories you may have, or any suggestions for diagnostic direction. To be honest, I may never be able to post a fix for this, as I may not have the chance to pursue this further. But, I'm very interested in what you might see here, and what test you might do next if this was in your bay/garage.
There are no stupid questions/comments on this one, so post 'em up!
[Last edited May 14, 2016 15:04:50]