[Diy_efi] pic based afm -> maf conversion

[Frey, Richard K]

Sounds like you understand the merits of each.  I think the application
might determine the need.  Personally, I would not be married to a maf
unless I was wanted to run right at stoich or leaner in a gas mileage
attempt.  The map is an easier install and works fine, GM has used 'em
for years but in the end fleet gas mileage is important so the switch
will (has?) occur(ed) because if you want super control over your
mixture a maf will work better.  Yes, a maf is more restrictive but is
the difference significant?  A common choice of maf in custom
applications is the one from a 5.0L mustang as it has a bigger bore and
will flow more air and is readily and cheaply available.  I think the hp
limit of that maf is about 500 or so hp so if less than that I think it
would be a good choice.

But then again, I am no car expert,

Rick frey

-----Original Message-----
From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]
On Behalf Of Ashley Evans
Sent: Wednesday, January 18, 2006 10:26 AM
To: diy_efi at diy-efi.org
Subject: Re: [Diy_efi] pic based afm -> maf conversion

Yes AFM is the flap device.

It's not Airflow that's required anyway.  It's air mass.  I'll rephrase 
my question.

Does anybody have any comments on the relative merits of MAF vs. MAP, 
given that calculation is required to generate the correct information 
for the ECU?

Personally I would have thought that the calculation is prone to error 
and the MAF will give a more accurate reading.  Having said that, MAP 
will mean there's no restriction on the intake which would obviously be 
more efficient.

But, I'm no car expert... hence my original question.

Ashley


Steve Ravet wrote:
>  
>
>
> ________________________________
>
> 	From: diy_efi-bounces at diy-efi.org
> [mailto:diy_efi-bounces at diy-efi.org] On Behalf Of Ashley Evans
> 	Sent: Wednesday, January 18, 2006 7:38 AM
> 	To: diy_efi at diy-efi.org
> 	Subject: Re: [Diy_efi] pic based afm -> maf conversion
> 	
> 	
> 	It's 5 (or actually ~4.9)  at WOT.  This goes for the MAF and
> AFM.  What differs are the idle outputs and the voltage curve to WOT.
> 	
> 	I'll post full details here once I get an operational version.
> As I'm sure there are many system that could benefit from this kind of
> thing.
> 	
> 	Never really considered MAP.  I'm not planning on FI atm. and
> many others on the e30zone (or which I'm a member) have done MAF
> conversions costing upward of 800+ , I was sure that there was a
cheaper
> way.  I'm expecting my conversion to cost under 100.  50 or so for the
> MAF, and under 50 for the PIC.
> 	
> 	For my application I can't think of a reason to go for MAP.
> 	
> 	Do you guys have any comments as to the pros and cons of MAP/MAF
> ?  For naturally aspirated.
>
>
> MAP and MAF aren't interchangeable like that.  MAP by itself doesn't
> give enough information to do fueling, it has to be combined with RPM
at
> least in order to calculate airflow.  MAF gives airflow directly and
so
> already has the RPM term in it.
>
> Is AFM the flapper door flow meter?
>
> --steve
>
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