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[Mark Eidson]

It is a heated sensor.  For some reason when the engine is not up to temp it
runs rich during first few first gear accellerations.  The loop corrects and
when the 1-2 shift occurs it is still correcting, making the new point on
the fuel map, lower RPM and Higher MAP, too lean and the system and either
backfires or hesitates.  If I manually shift at higher RPMs there is no
problem either.  Once the engine is warmed up there are no problems.  I like
the unit pretty well but would like to make my own system some day.  I guess
that's why I'm on this list.  me

At 11:21 AM 3/14/97 -0600, you wrote:
>From: Mark Eidson <mark.eidson at tempe.vlsi.com>
>Subject: Lean mixture on 1-2 shift
>Sender: owner-diy_efi
>Precedence: bulk
>Reply-To: diy_efi
>
>Does anyone out there have a theory that explains why on my Holley 4di
>system the mixture goes lean and boggs during the 1-2 up-shift at
>constant
>throttle positions when the engine is not fully up to temperature and in
>closed loop operation? 
>
>I don't know if you have answer yet, but I can shoot something at you.
>
>If you are in Closed loop and the engine is not fully warm, the mixture
>will be lean because the O2 sensor is not up to 600 degrees yet.  I
>would look at installing a Heated O2 sensor or check the engine temp to
>ensure it is up to 170 or higher engine temp.
>
>Just an idea.  
>
>Do you like the 4di?  I have thougt about a setup like that, but I want
>to install SPFI on my 80 Turbo T/A, which now has a 400 Pontiac, but
>will get a beefier 301 Turbo (stock 301 Turbo ran 14.21 at 97.3
>uncorrected), any ideas?
>
>Thomas Martin
>
>
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