[Diy_efi] Formula

[Mike]

At 09:09 PM 29/8/2002 -0700, you wrote:
>Mike,
>Is it pretty close to a true log curve ?

Yes - and I think from memory (having read a bosch release some
15 years ago ) its a log to base 10 - well would have to be I suppose
as a log to base 2 would be pretty lame,

>I have a Bosch I'm planning to use on a project, and
>I still am not sure what to use to approximate the curve, math wise.

Just use log 10 but add an offset to match the dc offset of the output
stage, ie. When I take a AFM out and power it up I get from 1.6 to
1.7v (no flow) and on the engine at full rating (of the AFM) the output
reaches
5v, on a practical engine where its not modded the AFM should never
actually read 5v but be a 'little' less, so the dynamic range is
only from 5-1.6v - some 3.4v - not a lot
but apparently enough for middling performance ;-)

Someone on the nissans13 group on yahoo once posted a short chart
which had air flow meters vs their CFM rating for max output - I think
there were only 3 or 4 listed, would be good to get this chart updated
and unfortunately I don't have a copy - but check/search with nissan13 on
yahoo,

rgds

mike



>
>Thanks
>-Les
>
>
>-----Original Message-----
From: diy_efi-admin at diy-efi.org [mailto:diy_efi-admin at diy-efi.org] On
>Behalf Of Mike
>Sent: Friday, August 30, 2002 1:27 AM
>To: diy_efi at diy-efi.org
>Subject: Re: [Diy_efi] Formula
>
>
>I don't know about uego.pdf,
>
>But i recall all the MAF sensors I have seen have a log output plus a DC
>offset - mine is around 1.6v with a maximum output of 5v dc from a 12v
>powersupply (actual range 8-14v)
>
>rgds
>
>mike
>
>
>
>At 01:35 AM 28/8/2002 -0400, you wrote:
>>Hello,
>>
>>I'm trying to decipher the formula for A/F to Vout. It is hand written 
>>on the fax which is part of the UEGO.pdf. I cannot make out the 
>>formula. Can you please reply to this email it with it.
>>
>>Thank you very much,
>>Mario Piquero
>>
>>
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