My car is a turbocharged 1990 BMW 325i running MS2 v3.57 that was pre-assembled. Wide band input is an AEM 30-4100, and the 0-5 volt is hooked up. My tune is fairly close, thanks to a friend, and 95% of the time it drives smoothly.
During normal driving/cruising, I get a random "jerk" that feels like the engine just totally quits for the tiniest fraction of a second. Then the wideband jumps totally rich, then settles back to normal almost in the same instant. You can see this in my attached data log. I've also attached my MSQ.
I thought was a rough spot or jump in the VE table. I had someone watch the VE table while I drove, and it didn't go across any transitions when it happened, so that ruled that out. I went ahead and pulled a log file (not something I'd done before). At one point, just so I could find it, I let off the accellerator & pushed in the clutch right after it happened so I could find it easily in the log file. I'm glad I did, because I didn't know what all I was seeing at first, but once I found the drop (right after the 4th highliht in the below image) I started seeing these weird spikes on y pulse width and duty cycle on both injector banks, thus causing the rich jump in the AFR.
MegaLog_Glitch2 by rtuite81, on FlickrThat made me realize that I'm hitting the acceleration enrichment, but I'm not sure what's triggering it. One post I found recommended checking for acceleration enrichment being triggered, which I am seeing on all the spikes. But, I'm not sure what's causing the trigger. I'm driving with the throttle steady, about 5-6%. Though I can't exactly log it, we watched my crank trigger output and it's rock solid. Here's where I'm stumped, and my Google powers are apparently weak. What else can cause the accel enrichment to trigger?