Does E30 have a "Safe Mode"? Could this be a Crank Position Sensor?

[nando]

I wouldn't know, I haven't had an AFM on my E30 for more than 10 years lol.

Well, I meant more that it won't run at all without the CPS - it will "run" with only the CPS and no other signals. However, I didn't say it would run well or be drivable. :p

[95BMWIC]

Im updating this as i had another issue.

After 300+ miles - driving along on Interstate at 80mph - suddenly began to lose power.. kept vehicle running by putting into Neutral and revving engine to get off and onto an exit. - Idled but would Hunt severely.. nursed it into parking lot... started the vehicle a few times checking different connections.. The car would always start- but would idle real, real rough.. No change when disconnecting AFM this time around.. Shut car off to make a phone call for recovery - started car - idled fine - drove 30 miles (45 minutes) back roads to home. no issues.

[95BMWIC]

The m20 will only idle if the AFM is bad or unplugged, it's not like a later cars with a MAF that has some sort of "default" if it's absent. Simple test, go outside, unplug the AFM and see if the problem replicated (I am pretty confident it will be). If it is, plug the AFM back in, and go home knowing you fixed the issue. :)

Replaced the AFM again (from another E30). The one that I switched to (after the video) was one that I took out of my daughter's E30 - and after a review of my notes - I remembered her car (according to her) was running rough and she through a code of 1215 and I pulled out her AFM and her check engine light went away. This was a while ago (Fall 2017) - and I didn't recall that fact when I put it in mine the other day. SO could I have had 2 bad AFM's? Not quite sure - but cant find a good way to test.

When the car is running fine - if I disconnect the AFM it will die - So when unplugging the AFM when it is running badly and it still runs badly - is that an indicator of the AFM.. or of the computer? I have 2 different scenarios above (first AFM unplugged it actually ran a bit better, plugging it in killed the idle and the second AFM unplugged didn't change it running poor).

[95BMWIC]

Ok - The engine will stall if I disconnect the AFM - HOWEVER if I leave the AFM unplugged - it will start and run..

There is a bit of a change once I plug the AFM in - a little smoother.

So I assume the current AFM is working fine..

The questions I am trying to reconcile.

Can a bad AFM cause real bad idle? Can it cause the car to suddenly lose power while driving constant at 3.5 - 4K RPMs.

Finally how does the AFM fail? i.e. AFM measures intake temp and if this fails, what are the symptoms? If the air flow potentiometer fails, what are the symptoms? AND Can these be intermittent?