daviddeep

iTrader: (4)

Per the FSM test procedure, I'm getting a resistance measurement between E2 and Vs of about 288 Ohm with the flapper door closed, but only 24 Ohm when the door is fully open. Specs call for 50-500 Ohm. Is this enough of a deviation from spec to suggest I need to replace it? There is also something small rattling around inside the AFM case.

My car is an '88 NA, low mileage (52,000) and everything is stock (except for a RB cat back). I'm having pretty severe low RPM hesitation and bogging. Car starts fine but idles roughly. Above 3500 RPM it feels normal. Last time I drove it for 20 minutes or so, I noticed the main cat and front of the Y-pipe were glowing. I have done a resistance test on the TPS and it appears fine. I know I have a lot more stuff to investigate and eliminate, especially looking for vacuum leaks and fuel delivery issues, but thought I'd start with the AFM.

When I bought the car 7 years ago, it had a K&N drop-in filter and it looked like the previous owner may have over-oiled it. There was a black tar-like goop inside the airbox which had seeped into the AFM. I cleaned it pretty thoroughly and carefully at the time, and the car has run great for years. Still, I wondered if the AFM had suffered some kind of long-term damage from the mystery goop.

Thanks for your suggestions.

-David

daviddeep

iTrader: (4)

Here's another odd detail I just discovered. I originally tested the AFM in my garage where the ambient temperature was about 90 F. I brought it into my house and left it sitting on my washing machine while I made dinner. When I just looked again at the AFM, the flapper door had somehow crept past the natural stopping position and was extremely resistant to being pushed open. Once I pushed it open, it sprang back to what I assume is the normal closed position. However for the first few times I manipulated the door, about 2/3 of the way through its travel, there was an audible clicking sound as well as a little friction. Has the change in ambient temperature from 90 F to 70 F made a difference in its operation somehow?

I'm getting more of a feeling this AFM has some issues.

barkz

iTrader: (1)

im sure satch will chime in soon, but just looking at the Specs it calls for and then your specs, its halved... i would saw theres an issue. but im not the most familiar with this. satch knows all lol

RTRx7

iTrader: (2)

Sounds like you have oil contamination with the door on top of the resistance being out of spec. It's time to get a new unit.

daviddeep

iTrader: (4)

Thanks for the replies.

I see Mazdatrix still stocks new Mazda OEM AFMs for the S4 NA, but they're $917! I wonder when the last time was that somebody bought one?

Is it wiser to get a remanufactured unit or to just find a working used one? My inclination is to spend the extra money for a reman one because it seems to me more likely that it will last vs. a used one of unproven condition.

I see that Rock Auto has two different brands of reman AFMs for my car: A-1 Cardone and Standard Motor Products. Both have a one year warranty, and they're within $25 of each other in price. Does anyone have any experience with either of them?

satch

iTrader: (1)

The remanufactured units are usually just cleaned and polished versions which often don't work worth a darn so you are much better off and buying a used one from a member of this site.

daviddeep

iTrader: (4)

I called Ray Crowe at Malloy just out of curiosity and he says the N326 AFM is now NLA. I suppose the Mazdatrix site may not be up-to-date on this. I guess I'll be hunting for a used one then.

Thanks again, everybody.

barkz

iTrader: (1)

mazdatrix has there own supply i thought? but like satch said grab a used one from here. also worth asking if the seller is willing to get a video of it running with that AFM