Saab 900T AMM (MAF) Swap

[Kevin Yachimec]

I had given the idea some thought myself.  I have a bunch of 1.9 liter ecm's
from the Ford Escort.  It also use's a VAF meter to measure the air entering
the engine.  The problem in switching to a MAF meter is it measuring the
mass of the air (temperature and volume in one signal) where a VAF measures
volume and temperature ( and volume are separate signals) then ecm
calculates the mass of the air.  If someone wanted to use a MAF meter in
place of a VAF you would have to build a circuit that removes or separates
the air temperature part of the mass measurement output by the MAF meter.
This isn't that hard to do.  The problem is that a MAF meter's output is
almost linear where a VAF meter's output is logarithmic.  A VAF meter is
very good at measuring a small air flow.  The circuit that converts mass to
volume would have to take this into account.  I'm not an expert on op-amp
circuits so I run out of knowledge when I got to this part of the circuit.
I think you could create a series of curves with different slopes and create
a response curve that is very close to the logarithmic output of the VAF
meter.  Maybe someone else in the group could help out.

If you don't want to built your own circuit to do the conversion a company
by the name Split Second has a device that does the it for you.
http://www.splitsec.com/ A friend purchased one for his 2.2 Ford Probe but
had a hell of a time getting it to work smoothly.

Kevin Yachimec
Cybertech Automation Inc.
Edmonton Alberta Canada
keviny at cybertech.ca

> Date: Mon, 12 Jul 1999 20:43:36 -0400
> From: bjanesi at juno.com
> Subject: Saab 900T AMM (MAF) Swap
>
> I've been off this list for some time, but have jumped back on now that
> I'm in the middle of a project that has some relevance.
>
> Specifically, I'm trying to replace the stock Bosch VAF meter in a Merkur
> XR4Ti (2.3L Ford Turbo) with the MAF (AMM in Saab verbiage) meter from a
> '86 Saab 900T (16v 2.0L Turbo).
>
<SNIP>