What's the deal with the current OE AFM part?

[BimwadM42]

I'm far from due for a new AFM, but after reading the thread about the MAF conversion, I got curious about the factory replacement part.

Apparently, the original part has been superceded twice, to one that now uses an adapter lead, and runs about $600(!).

At first, I thought it might be a super-duper updated part, but it just looks like another flow meter with an short wiring harness, not some sort of mass meter conversion.  And if they are requiring cores, what are they doing with them if they're not selling them as replacements?

Heck, for that kind of money, we can hope that bmwman completes his project, and provides a solid-state alternative for less cost.

[DesktopDave]

Absolutely, it'll be great to have an alternative.  BMWMan's attention to detail is a real win for us here.

I don't think anyone actually buys new ones, at least not for performance bargains like our little M42s.  If it was some high demand rare/exotic machine like an Alpina B10, perhaps.  I'd figure the e24 guys in particular might go for these units.  They're often in the market for OEM equipment - almost regardless of cost - as there are frequently no better alternatives given the scarcity of a few of those models.

If I had to reproduce those parts I'd use a flying lead too - that's one less part to reproduce.

[///m42 sport]

solid state alternative?

[bmwman91]

All of the "OE rebuilt" AFMs are used stock ones that have had minor tweaks and cleaning inside the cover. It is all stuff that anyone could do themselves. Truly, the AFMs are not the crazy delicate contraptions that everyone seems to think that they are.

The pig-tail harness thing is, as far as I can tell, an active filter. Basically, it is on there to dampen out oscillations in the readings so that the ECU can read the average air flow value at low flow rates. It probably hurts response speed a little, but it is better than having a crappy idle. I think that some of the "RPM seeking" issues that many E30 M42 owners have is due to this, and the little pig-tail helps eliminate it. That's my guess, anyway.

[bmwman91]

All of the "OE rebuilt" AFMs are used stock ones that have had minor tweaks and cleaning inside the cover. It is all stuff that anyone could do themselves. Truly, the AFMs are not the crazy delicate contraptions that everyone seems to think that they are.

The pig-tail harness thing is, as far as I can tell, an active filter. Basically, it is on there to dampen out oscillations in the readings so that the ECU can read the average air flow value at low flow rates. It probably hurts response speed a little, but it is better than having a crappy idle. I think that some of the "RPM seeking" issues that many E30 M42 owners have is due to this, and the little pig-tail helps eliminate it. That's my guess, anyway.