One way to figure this out is to connect a MAP to the engine with a known good AFM. Then, compare the values. Since it appears AFMs are linear, and so are MAPs (at least the ones I looked at), a circuit could adjust a MAP output to simulate an AFM. Jon On Sat, 4 Nov 2006, Geza Polony wrote: > This is a question I've been asking for a long time, both here and on > westfalia.org, and no one seems to know. You're right, there must be SOME > concrete relationship between manifold pressure and AFM output voltage, but > no one seems to know what it is. The Bentley doesn't help, either. I took > mine off and measured the voltage using a hair dryer to simulate the air > flow, but that doesn't really tell you anything except that the voltage does > change, and pretty much evenly. > > Without knowing what the voltage should be for a given set of AFM > conditions, it's impossible to calibrate the AFM. And you can bet that, with > most of these AFM's having 20-odd years on them, the voltage output "ain't > what it used to be." That would mean that at some point in the scale of air > flow, the engines are running too rich or too lean. > > Unless there's something we're not getting. Why wouldn't the voltage data be > available? > > ?? > > Geza > > On Fri, 3 Nov 2006 18:22:51 -0800, jon <jon@KENNEKE.COM> wrote: > > >Does anyone have data on AFM voltage (out of the resistive divider) versus > >manifold pressure? I would think they would directly correlate in some > >linear fashion. > > > >Yes, I think of these types of things on a Friday night. ;) > > > >Jon > |
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