Phil Kangas wrote:

> Perhaps you changed something that controls ignition action?
> Like, something is changing the spark timing and it is now
> far
> too advanced? Spark knock? Maybe? hmmm....

I hadn't thought of that, where I did recently install the BMW dealer
software of the era when my car was new called INPA which allows me to read
all the electronic control units and reset the codes for all modules (not
just OBDII modules):
<https://www.turboimagehost.com/p/36851946/inpa1.jpg.html>

Some of this BMW dealer software can also program each module but I didn't
run any of that, and it can reset something called the "adaptations",
again, which I didn't touch to my knowledge.

I should be able to get the spark advance out of the dealer software though
<https://www.turboimagehost.com/p/36851948/lean1.jpg.html>

My OBDII reader shows spark at 6 degrees advanced at idle and then it jumps
to 20 and 30 degrees in the live data as I drove - where I don't actually
know what it's supposed to be. I don't even know where that data is.
<https://www.turboimagehost.com/p/36851949/lean2.jpg.html>

I have heard spark knock before where it sounds like marbles under load.
This doesn't sound like marbles. It sounds more like one marble.