Date:         Sat, 11 Nov 2000 17:47:44 -0500
Reply-To:     Gary Stearns <gstearns@SPRINTMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Gary Stearns <gstearns@SPRINTMAIL.COM>
Subject:      Digifant Operating Specs
Content-Type: multipart/alternative;

Maybe only Bosch or VW engineers know this, but the list has amazed before...Over the past few months, I have run our '88 with the O2 sensor disconnected (open loop).  I did this so that I could manually adjust the AFM spring tension and wiper static setting and live with it awhile under various conditions without fighting with the ECU.  Lots of fiddling later I do have open loop settings that allow the WBX to run right.  Rock steady idle (though cold is still an issue) and plenty of power.  Today I again connected a digital multi-meter to the O2 sensor while still keeping it disconnected from the ECU. This setup allowed me to drive with the multi-meter propped on the dash.   I had found earlier that our engine will not run right (too lean, stumbling acceleration, lousy throttle response) with O2 sensor outputs in the .5 range where I had seen the list suggest that they out to be.  I find that my manual S.O.P. (seat of the pants) adjustments have left me with O2 outputs in a fairly constant (doesn't fluctuate too much) .75 to .88 range.  I next reconnected the O2 output to the ECU while keeping the multi-meter connection piggy-backed as well.  Now the O2 output changes quickly as the ECU is trying to adjust.  Output appears to go from .55 to .90.  A little more lean hesitation at lower rpms, but the high rpms seem to run more cleanly.

My question (finally) is:  what O2 sensor output range is considered normal with the ECU adjusting things?  I thought that the O2 sensor / ECU combination attempts to adjust for no excess oxygen or a 0.00 voltage.  Our WBX might run at this level, but it would run terribly.  At what output levels does the ECU go "out of range" and give up defaulting to open loop again?  With non-spec  AFM settings am I forcing it to go open loop or even fluctuate between open and closed?  
Thanks-

Gary

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