Re: EPROM tuning head start

["NickG" <nikog@mediaone.net>]

You have to realize that (usually) the blocks encompass more than one map
value. You can't assume that since one BLM value is at 120, that all of the
map locations that are in that particular block need to be modified by the
same amount. You have to tune each and every map data point individually.

Also, you have to be careful under what weather conditions your tuning is
done. For example, you can tune one area of the map during a 90 degree day
with 100% humidity, and get the BLMs to 128. The next weekend a cold front
comes in, with temps in the 60s, and 40% humidity. Guess what, the BLMs are
drastically different now. Many people will think, "oh no, the maps are
still wrong, I need to keep tuning."

No, you don't. You have to try and do your tuning on days with similar
conditions, and keep good notes on what areas you've already optimized. If
you don't, you'll NEVER finalize the chip. It'll be like a cat chasing its
own tail.

Nick

> Date: Mon, 7 Aug 2000 03:33:00 EDT
> From: WEG1192@aol.com
> Subject: Re: EPROM tuning head start
>
> Some thoughts on this (7747) tuning methodology. From the tuning tips it
> appears that spark timing is the first to tune since the BLM can keep the
car
> running even without a "perfect" fuel map. If you don't have a scanner or
> Diacom, could you use a DVM on the TPS, a vacuum gauge and a tachometer.
Do a
> run and keep the vacuum and tach steady with throttle (TPS). Note TPS
value
> that this takes. Advance timing in the spark table corresponding to the
> vacuum and RPM. Do run again and watch for a significant increase in TPS
to
> keep car at same RPM and vacuum. This would indicate knock retard I
believe.
> Back off timing and do run again to make sure of max. timing before knock
> retard. Do all cells of BLM this way, assuming the BLM cell boundaries are
> known. Then, drive car until all BLM cells have had a chance to settle in.
> Then note the value of each BLM cell away from 128. Now, is there a way to
> correlate the amount the BLM is away from 128 to the amount needed to
adjust
> the VE vs. RPM vs. MAP table? If the goal of tuning is to get the BLMs at
128
> or slightly smaller, why not let the BLM tune for you and get you homed in
> much faster? If the BLM is at 120 in a certain cell, why not remove a
> specific amount of VE from the table to increase the BLM by 8 points? If
this
> is possible, anyone know how much VE corresponds to one point in the BLM?
> This may vary by RPM, MAP, etc., so any comments on the concept? From here
> check the BLMs once a week and adjust VE to move BLMs back to 128. Tune
WOT
> standard way.


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