Date:         Sat, 4 Nov 2006 13:39:42 -0700
Reply-To:     Keith Hughes <keithahughes@QWEST.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Keith Hughes <keithahughes@QWEST.NET>
Subject:      Re: Replace AFM with MAP?
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

>Date:    Sat, 4 Nov 2006 09:33:53 -0800
>From:    jon <jon@KENNEKE.COM>
>Subject: Replace AFM with MAP?
>
>Has anyone experimented with replacing the AFM with MAP? I know that
>Megasquirt requires running a vacuum line to it's MAP, but what I am
>talking about using a MAP with Digifant(jet).
>
>Jon
>
Jon,

As others have replied, you cannot replace an AFM with a MAP without
totally reprogramming the ECU.  The ECU currently measures the flow rate
and air temp to estimate the mass airflow.  To get the same info from a
MAP, you would additionally need to know engine RPM and throttle
position.  What you *could* do, if you knew, precisely, what the signal
voltage / CFM profile of the AFM was, is to source a MAF (mass airflow
meter) that was fairly compatible, then build a voltage
divider/conditioner to condition the MAF output.  Not impossible, but
certainly not easy, nor cheap.

Keith Hughes
'86 Westy Tiico (w/Motronic that *has* the TPS/MAP system)