IAT sensor ?

[Bruce Plecan]

MAT does allow for some correction due to fuel temp.
Bruce



> Practically speaking are they not the same?  Manifold Air Temp & Intake
Air
> Temp?  the MAT is the air temp taken @ the plenum & IAT is usually taken @
> the air filter housing (or air intake tubing)?  the real difference is
that
> the Manifold heats the air up some as it goes into the motor so the
> calibration (or more accurately the amount of influence that this
> compensation factor has on IOT) is quite a bit different.
>
> My car has MAT & I noticed that the temp of this air is rather constant
> regardless of ambient temp.  where the air filter housing that I have is
> from a TA & it has a location for a IAT sensor & I would imagine that the
> swing on this one would vary by a bunch.
>
> this being said the actual amount of air flow through the engine (density
of
> the air) would not change by much depending on the ambient air (NA only,
not
> blown), because of the heating of the air as it gets into the plenum.
>
> this leads me to think that the car that has IAT has to filter (firmware
> filter) the change or reduce the affect that it has on IOT compared to the
> MAT car, as a small change there would be a larger change in ambient air.
>
> in either case, the compensation that this algorithm provides ought to
keep
> the motor on an even keel regardless of ambient air.  I guess this comes
> back to how to prove either way how much of an affect this has on what.
we
> talked about this before & Bruce pointed out a number of other factors
(fuel
> temp etc) that would be hard to keep as constants to prove one way or the
> other how much of an affect this sensor/the actual temp of the air has on
> the "tune up".
>
>
> BW
>
>
>
>
> -----Original Message-----
> From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
> Behalf Of Bruce Plecan
> Sent: Sunday, March 25, 2001 10:15 AM
> To: diy_efi at diy-efi.org
> Subject: Re: IAT sensor ?
>
>
>
>
> IMHO, just as critical as Coolant temp for a Hipo daily driver (all year /
> weather).   Even better is a MAT.   Also, depends some on if MAF or MAP
> system.  Given enough resolution, the importance would vary
> Bruce
>
>
>
> > Does anyone have an opinion on how large a role the
> > IAT sensor's output signals is in determining pulsewidth
> > and timing in any stock efi system, specifically in WOT
> > mode on a NA engine?
> >  From the search's that I've done on this efi management,
> > my understanding was its role would not be significant,
> > with its most significant influence limited to one or two
> > modes of operation (WOT not being one of them).  On
> > the other hand, my search's on relocating the IAT and/or
> > sending a false signal to the computer seem to indicate
> > that timing can be affected by as much as 3 degrees
> > and that the afr is also significantly altered.
> > As always, any thoughts are most welcomed and
> > appreciated.
> > Bob
>
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