165 $6E cold idle

[Marteney, Steven J.]

Good plan, unfortunately, my Diacom interface won't talk using the special
TPI adapter, and therefore no spark or LV8 information is provided.  I
assume if the engine doesn't correct for fuel when cold it looks like a lean
condition?  (Cold air = more dense, so more air flows in for given TPS?)
But then, wouldn't the MAF see more air and give more fuel?

Guess I could just burn a test chip with many of the lower rpm/LV8 areas of
the spark table set to a constant (low) value and go from there.  Damn,
starting to sound like recommendations from Tuning Tips and Prog 101.  Maybe
there's something to those docs after all <g>

Steve

-----Original Message-----
From: romans at starstream.net [mailto:romans at starstream.net]
Sent: Monday, February 12, 2001 11:00 AM
To: gmecm at diy-efi.org
Subject: Re: 165 $6E cold idle


>From what I have seen the 6E code doesn't even use MAT for any corrections
to timing, maybe fuel through.
The main cause of idle stability issues I have seen is spark variation in
the map.
If you record a cold start on diacom and look at the spark timing and where
it
is on the map (LV8 and RPM) if you set all the timing in that area at the
same
amount of advance it greatly stabilizes the idle. (In my experience)
Mark
----- Original Message -----
From: "Marteney, Steven J." <smarteney at xlvision.com>
To: <gmecm at diy-efi.org>
Sent: Monday, February 12, 2001 7:10 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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