after some more research, I think i'm getting a better idea of what a
logarithmic reading means.
after all, the peugeot book doesn't say clean sweep, or where its
going to hit the highest value (1000), just that it should be between
60 and 1000..
its too bad they don't spell this out a little clearer in the manual,
that'd be nice. then again, it would also be nice if they actually
told you what you were checking (rather then pin x and pin y should be
XX. <-- period).
On 12/13/05, Brian Holm <peugeots@vtlink.net> wrote:
> I have tested about 20 N9T AFMs and found the same thing. Also the same
> with fuel level senders. I think that an ohm meter simply isn't the
> instrument to use where the conductive characteristics of the swept surface
> may mask the fundamental resistance, due to dirt, corrosion, and minute
> pressure fluctuations of the slider. A log scale is not linear, it just has
> the greatest sensitivity with lower values, but it does not reverse itself!
>
> Brian Holm Parts for peugeots
>
>
> At 01:38 PM 12/13/2005, august wrote:
>
>
> Interesting Bob, thanks for that info, your totally right.. I did a
> little research and found the same thing:
>
> Right from the Bosch book of Automotive Fuel Injection Systems Technical
> Guide:
>
> Page 100
> "The relationship between the mass airflow and the flap angle is
> logarithmic, which ensures a non linear characteristic in the
> potentiometer."
>
> i take it logarithmic means its not linear (obviously), but it will
> fluctuate during the complete sweep of the flap.
>
> I asked another friend / peugeot homie who said:
> "it should read the highest value when the flapper reaches to most
> deflection it can attain with airflow pushing on it"
>
> Bob, is the AFM you have for sale new? Would you be able to test it?
>
> On 12/13/05, Bob Bruce <bobbruce@mts.net> wrote:
> > Bosch info states that these AFMs are logrithmic rather than linear
> > if anybody knows what that means
> > Apparently this explains to the whizes why the resistance readings are
> > not what you might expect as in a light dimmer
> >
> > Bob
> >
> > PS I have a spare turbo AFM forsale with airfilter and box
> > ----- Original Message -----
> > From: Bill
> > To: peugeot-L@yahoogroups.com
> > Sent: Tuesday, December 13, 2005 12:07 AM
> > Subject: [Peugeot-L] Re: 505 Turbo AFM checks
> >
> >
> > I've seen the same behavior on different units.
> >
> > -Bill
> >
> > --- In peugeot-L@yahoogroups.com, august <august.macbeth@g...> wrote:
> > >
> > > There's one test shown in the N9T/N9TE/N9TEA for checking the AFM:
> > >
> > > Connect an ohmmeter between pin 5 and pin 7 of the AFM. Then move the
> > > flap door slowly to full open.
> > >
> > > It says it should be between 60 and 1000 ohms.
> > >
> > > Now, I've done this test on 4 AFM's. You'd think that whatever the
> > > value the book was calling for would be a clean sweep from low (full
> > > shut), to high (full open). Not the case, on all FOUR that I have.
> > > They seem to jump around a lot. As the doors opens, the value rises,
> > > but can go up and down, and full open on all isn't the peak value.
> > >
> > > (more like, 60(door closed), 100, 300, 150, 500, 800, 200, 900, 400
> > > (full open))
> > >
> > > Is this normal, or do I have a bunch of bunk AFM's?
> > >
> > > Here's a sample reading:
> > >
> > > full shut: 80
> > > peak: 1000
> > > full open: 450
> > >
> > > Do any of you have experience with this? Or would any of you be
> > > willing to test the AFM's you have? I've been looking around the net
> > > to try to educate myself on exactley how these things work, but
> > > haven't found anything on super bouncy readings.
> > >
> > > thanks!
> > > /august
> > >
> >
> >
> >
> >
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> Brian Holm, Parts for Peugeots
> at Peugeot Holm, since 1969
> 2120 Maple Hill
> Plainfield, VT, 05667
> 802-454-7132, fax -1310
>
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Received on Tue Dec 13 15:01:23 2005
