I thought I read this on the forum long ago, but now I cannot find the thread...when you fail the MAF (not sure on E38 only, or all Gen 4's), the engine will randomly stumble or hiccup while steady state cruising. As I recall this is "normal" and there is nothing that can be done about it, and it won't hurt the car.
Still, I thought I would reach out about this. I recorded this log the other day. There were two stumbles 4 seconds apart. What appears to be happening is that the calculated cylinder airmass spikes which then causes the injector pulse width to spike.
My only guess this that the zero g/s being reported by the MAF is throwing off the Engine > Airflow > Dynamic > Prediction Coefficients (or at least the formula using the prediction coefficients and the MAF input). Is there a work around to this?
stumble.jpg
E38 MAF Failed Stumble.hpl