Mass airflow sensors.

[Andrew Brownsword]

Hmmm... this is a strong argument for converting to speed/density.  The 
pressure change should be instantaneous -- or at least as fast as the VAF
signal change.  Another issue that has been brought up is that a MAF might
not work well in a boosted situation like mine... it might not be pressure
tight and will get dirty quickly if downstream from the turbo.  I don't have
room to put it upstream.

These factors make the LinkAFM look more appealing again.  My theory on the
Link is that they built it to replace MAFs or flapper-door style VAFs, so
they will have attempted to generate a signal that is reasonably compatible
with a MAFs output.  This gives me a baseline to start with, and tune on the
dyno from there.  I suppose it doesn't hurt to ask:  does anyone have the
output plots from a conventional flapper door style VAF?

Somebody else pointed me to the HKS Vein Pressure Converter, which acts in a
similar manner to the LinkAFM.  It is considerably more expensive, and LESS
easily programmable, however.  Anyone know of any other options?

Thanks for bringing up this issue, I had been concerned about response times
but had heard/seen no mention of it anywhere.

Cheers,
  Andrew


----------
>From: "nacelp" <nacelp at bright.net>
>To: <diy_efi at diy-efi.org>
>Subject: Re: Mass airflow sensors.
>Date: Sat, Feb 19, 2000, 5:02 AM
>

> How about adding a MAP sensor, and looking for a sudden change in that?.
> Grumpy
>
>
>> Hi,
>> I'm also working on converting my AFM to MAF but I've ran into a
>> couple problems that I don't see mentioned here.  The response
>> time of the AFM to changes in air flow is almost instantaneous.
>> However, the MAF (GM hot film sensor) requires about 200ms to
>> fully react to a change in flow.  If I map the MAF signal to an
>> equivalent AFM voltage, the car runs great, as long as I don't stab
>> the gas.  If I do, I basically go very lean for 200ms resulting in a
>> very nasty head jerking event.  My thought was to use the
>> derivative of the TPS signal to compensate during the 200ms.
>> Unfortunately, my car doesn't have a TPS.  If there any way to
>> accomplish what I want or do I have to add a TPS?
>>
>> Any thoughts?  BTW the car is an 88 BMW 535i if that helps.
>>
>> Thanks.
>>
>> Brian Franchuk
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