165 $6E cold idle

[Bob Wooten]

I would think that in regards to the MAT that the location is not as
important as the change in output for a change in temp.  assuming that the
motor was tuned to where it ran well (w/an air temp of X), if the temp went
down by 5% you would expect that the MAT would report the 5% change.  now
the ECM could compensate by the 5% (or some reduced/enlarged percent) for
that change.  the only down side that i could see to having the MAT on the
bottom of the manifold is that it is hot all the time & it makes me wonder
if it is seeing the air temp change. 

the reason for interest here is that i just put a fresh air package on my
car.  previously i had a K&N connected to the TB & was sucking in nice warm
air right from the radiator.  in a black car, in traffic, in S. California
the MAT temps were very high (sorry don't have #'s right now).  when i went
to the fresh air package i thought that the MAT temps were going to drop 40
- 60 Deg or so but that did not happen.  I am truly taking the air from in
front of the car.  this leads me to think that the sensor connected to the
manifold dampens the response, maybe saturation from the plenum into the
sensor.  

the air filter canister that i have is from a  Firebird & it does have the
hole for the MAT, but is it that important?  The temp of the air certainly
affects the density of it.  & most cars tend to run faster when the sun
starts to go down & the air temp drops.  so this leads me to think that
this does have a fairly sizable impact on the hp the motor is making but it
just does not seem to pan out.  what am i missing?  maybe i will start
another thread on this subject.  this leads me to thinking about density &
speed density systems & PE mode.  

I am headed back to the track in a few weeks.  maybe i will take the old
filter with me & do a back to back run with the fresh air & W/O & see if i
can time (& record with data master) a difference. 

Thoughts?
BW


> [Original Message]
> From: Marteney, Steven J. <smarteney at xlvision.com>
> To: <gmecm at diy-efi.org>
> Date: 2/12/01 7:22:45 AM
> Subject: 165 $6E cold idle
>
> Found my idle problem this weekend... cold weather.  The weather here
(East
> Coast FL) went cold for the first time since I started playing around with
> closed loop disabled.  Both my lean and rich chips ran like crap.  This
> weekend, both chips ran great.  The lean one's idle was a little rough,
but
> not that bad with the low end of the MAF Scalar table turned up a bit.
> Looks like I've got some cold weather idle tuning to do.  Any thoughts?
> 
> Here's my thinking.  With the MAT sensor located under the plenum, it's
> coupling all the heat from the motor.  The MAT readings from a cold to a
> warm day only differ by about 6-10 degF, even though outside air temp is
30+
> degrees below normal.  Would relocating the sensor away from the motor
help?
> (Thought about mounting it to the air filter can, right fender well in TPI
> Firebird.)  Or, can the air really warm-up that quick when it enters the
> plenum?  In that case, is the problem the MAF sensor is giving an
erroneous
> reading from the cold air?
> 
> Any suggestions are definitely welcomed!!!
> Steve
>
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--- Bob Wooten
--- r71chevy at earthlink.net
--- www.r71camaro.homestead.com



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