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Discussion Starter #1
It's time to change my 164 Super's stock AFM. Before buying a new one i was wondering if somebody changed the AFM system to a MAF (hot wire) system. I read guys in the US did it and other on the BMW forum did it too with excelent results. But the articles are not very informative as how it's done. Somebody know about this?
Cheers
Chris
 
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I'm more or less with Richard on this.

Any replacement of the AFM with a MAF will have to provide identical replacements for the AFM signals (Air flow and air temperature) or the 164 ECU would not be able to interpret them.

The AFM indicates flow by providing a signal voltage from the moving arm of a potentiometer. Air temperature is taken from a thermistor.

The MAF maintains a constant resistance of a fine wire by varying the current through it in accordance with the cooling effect of the air flow over it. I don't know whether the MAF is intelligent and does this itself and then reports the voltage required or if the ECU has to take charge of the whole process. Plus the air temperature sensing of course.

To use a MAF would I think entail the building and calibratring a control unit that would drive the MAF sensor and convert the data into a form that could be used by the 164's ECU. The electrical system is complicated enough already!

I reckon it would be easier to put the engine onto Dell Orto carbs (but unlikely to pass emissions test)!

Can you put up some links to the chaps who have done it Chris?
 

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Discussion Starter #5
oh, but it can be done and it has been done.

simply type "afm maf" on google and you'll probably end up tomorrow reading experiences from BMW, Alfas, Toyotas, Pugs, etc., along with companies selling some kind of conversion kits. The thing is that I'm still not very convinced as to what I loose if I go for it.

here's just 1 company that sells conversion kits http://www.splitsec.com/
the big australian autospeed online mag (www.autospeed.com) sells/promotes another kit that is popular down there.

but I'm quite "lean" on experiences on other Alfas.
 

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The thing is that I'm still not very convinced as to what I loose if I go for it.
If you're planning on using the normal Alfa fitment (Bosch I think), then the first thing you're likely to lose is relaibility - if you look around on here & other Alfa forums, you'll see the hot wire system is almost an expendable like tyres, where as I can't recall anyone actually having to change the flap type meter.


Incidentally though, isn't the MAF the earlier system (measuring mass) & the AFM (measuring cooling of the hot wire as an analogue of air flow) the later?
 

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Their kit appears to include a calibration box which takes the signal from the MAF and turns it into a voltage that mimics what the flap-type air flow meter would have produced. In this way, the engine's ECU doesn't "know" that the signal it's getting hasn't come from the old flap-type airflow meter.

To be honest, I don't think I'd bother because the flap type meters are extremely reliable and I wouldn't have the time or equipment to "map" the whole system again and optimise it for both power and economy. Maybe if they produced one specifically set up for the 164, AND I had heard good independent reviews of it, I MIGHT be tempted but just using one of their universal kits would, I think, be a bit risky. Too lean and you trash your engine. A bit too rich and it gets very thirsty. A lot too rich and it will trash the engine.
 

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Discussion Starter #8
Maybe if they produced one specifically set up for the 164, AND I had heard good independent reviews of it, I MIGHT be tempted but just using one of their universal kits would, I think, be a bit risky.
Amen. That's why I originally posted calling for previous experiences on Alfas.
 
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