Let's Talk AFM's

[66Vette]

I've got an M20 in a BMW 2002. It's a little bit of a mystery motor so I am going through various pieces to improve reliability. My latest focus is the AFM. I'd like to buy a refurbished AFM (Bavarian Restoration) or even get the Panzer Performance digitized mod.

In my pile of junk parts I have a new Cardone "remanufactured" AFM for the M20, though the plastic cover on the top says "Ford". My understanding is this part number was also used on Mustangs?

I've also noticed that there are offshore reproductions for around $120. I'll assume these aren't a super reliable part. I'm not ready to switch to a MAF and new ECU, so for now, I need a quality, reliable, AFM.

Hoping the experts can school me a bit.

[82eye]

rock auto has refurb ford branded afms that will work for a while at least. i can't confirm they are identical but that is what will show up most times if you order. blue streak refurbs them. pretty sure cardone reboxes them. take that for what it is worth. most of those are china work. do a quick google on them.

edit: they have the rep you would expect for a tin bin part.

if you are wondering why ford, bosch was used extensively in both bmw and ford.

[e30m3s54turbo]

I've got an M20 in a BMW 2002. It's a little bit of a mystery motor so I am going through various pieces to improve reliability. My latest focus is the AFM. I'd like to buy a refurbished AFM (Bavarian Restoration) or even get the Panzer Performance digitized mod.

In my pile of junk parts I have a new Cardone "remanufactured" AFM for the M20, though the plastic cover on the top says "Ford". My understanding is this part number was also used on Mustangs?

I've also noticed that there are offshore reproductions for around $120. I'll assume these aren't a super reliable part. I'm not ready to switch to a MAF and new ECU, so for now, I need a quality, reliable, AFM.

Hoping the experts can school me a bit.

Is your motor from a 325i and a 55 pin ecu 173? If it is you can delete AFM and you can buy Mega Squirt II stand alone. You will have to get a tune for it.

[TobyB]

a quality, reliable, AFM.

yeah, that's been something of a challenge for at least a decade, now.
Which is why the MAF conversions are so popular, and once you head down that slope,
an aftermarket ecu is only an incremental cost...

Most of us who stick with the AFM just keep trying them until one sticks. It's not a great solution,
but 'market forces' don't support much else.

In a non- E30, I would not hesitate to stick a Megaquirt on there, 3 DCOEs, or even a Holley....

Thinking about it, though, a known- good MAF, a MAP, an arduino and relatively little fussing around,
and off you go...

t

[66Vette]

Guys, thanks. For now, I would like to keep the motor with the stock ECU. I am guessing switching the ECU would not be a painless experience. I'm an electrical engineer, but loathe chasing down digital gremlins. Car runs fine, but would like to get it as good as I can in the stock format.

Any experience with Bavarian Restoration or Panzer for the AFM?

[Tibboy12]

100% recommend Bavarian Restoration. I was chasing a misfire/idle issue with my m20 and it was the AFM that went bad. Theirs fixed the issue!

[DesertBMW]

I own E30 cars for 30 years now, not ever had I AFM fail on me, ever. They are simple to test, there is not much to them, it is just a potentiometer resistor. People have other issues with their M20 and they start blaming the AFM.

[AWDBOB]

I vote for a good used AFM.

M20s feel so much better with a standalone. Spending half of a pnp standalone budget on an AFM seems silly, unless you're limited by a class, like spec e30 using the Panzer.

[e30davie]

yer a standalone really woke up my m20. Proper TPS and really dialing in the throttle pump enrichment made it so nice to drive. so crisp on the throttle, rather than relying on a mechanical vane to open....even the most basic ecu is an upgrade to 1980s motronic.

Each to their own, but I would be quite hesitant with these "afm conversions" as you are relying on the transfer function programmed in, and it becomes a bit of a black box of unknown for diagnosis, but again some people swear by them. I would only use an oem one, or a refurbed oem - and like was said above, its just a variable resistor. not much to them.

[packratbimmer]

I own E30 cars for 30 years now, not ever had I AFM fail on me, ever. They are simple to test, there is not much to them, it is just a potentiometer resistor. People have other issues with their M20 and they start blaming the AFM.

Same here. Never had a failure. The carbon band can get worn away, but you can just bend the wand to make the contacts run along a different area on the carbon band.

[TobyB]

and like was said above, its just a variable resistor. not much to them.

Watching the PRO3 crowd struggle, it's supposed to be a very precise measuring device that gives an accurate, repeatable number
that needs to be calibrated internally. As in, the DME doesn't do much calibration for variation after the fact, especially in the WOT tables.

It's not very good at that.

Good enough for a street car in 1984, but then, at that point, it was competing with 'emissions carburetors' so the bar was pretty low.

We're spoiled, I suppose.

t
never knew how good he had it.

[66Vette]

Toby, are the PRO3 guys using the Panzer modified AFM's?

[TobyB]

It's been allowed since last season- I haven't gone asking around, though.

t

[66Vette]

Thanks Toby, appreciate the feedback.