Date:         Sat, 1 Nov 2003 11:01:25 -0700
Reply-To:     Jeff and Tamara Nelson <ramjeff@EARTHLINK.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Jeff and Tamara Nelson <ramjeff@EARTHLINK.NET>
Subject:      Re: Question About ECU Programing
Comments: To: "Loren A. Busch" <lbusch@IX.NETCOM.COM>
In-Reply-To:  <000101c39f6d$25647ca0$41b0fa43@hewlett2ih5nie>
Content-Type: text/plain; charset=us-ascii; format=flowed

Why would the city requirements be different that highway?  The ECU can
change its outputs (ignition timing, air/fuel mix, etc.) faster than the
various cylinders fire.  Once the engine has reached operating
temperature, it shouldn't matter whether it stays at the same RPM for
hours or seconds.  The ECU is adjusting its outputs every few
milli-seconds or so based on the inputs it receives.

My opinion would be that any 'adaptation' that is 'remembered' would be
intended to handle things like spark plug wear, coil inductance
differences, 12V supply level, O2 sensor characteristics, etc.

This is all just my guess, it would be interesting to hear from someone
in the biz who really knows...

-jeff

Loren A. Busch wrote:

> Let me pose a hypothetical to the list:
> I'm familiar with the instructions for 'reprogramming' the ECU after the
> power has been disconnected.  These instructions imply that the ECU will set
> itself up for the type of driving that is being done.  That further implies
> that there is a possibility of getting 'best performance for conditions' if
> you were to 'program' the ECU based on anticipated 'most of the time'
> driving conditions.  EG:  I'm planning on a long trip at highway speeds and
> conditions, so just before I pull onto the freeway I stop, disconnect the
> battery for a couple of minutes, reconnect it, start up, pull onto the
> freeway, and proceed with my trip.  When I get home and know that I'll be
> doing all my driving around town for the next few weeks I repeat the process
> but go about my normal 'in town' driving patterns.
> Now, for those of you that better understand to way the ECU works, would
> what I just described make any difference, good or bad?
>