IAT sensor ?

Bob Wooten r71chevy at earthlink.net
Sun Mar 25 19:00:55 GMT 2001


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

----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org

----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org




More information about the Diy_efi mailing list