Date: Mon, 2 Dec 2002 23:38:18 -0800
Reply-To: joe brown <uastar2@YAHOO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: joe brown <uastar2@YAHOO.COM>
Subject: Re: WOT switch and digitool O2 decipher Qs
In-Reply-To: <20021202051048.62603.qmail@web13105.mail.yahoo.com>
Content-Type: text/plain; charset=us-ascii
The full throttle switch at WOT bypasses the O2 sensor signal and goes to the preset ( supposed to be) slightly rich AFM base signal. With my dash mounted digitool when I go WOT, going up a hill or something, my O2 reading goes to .75v. According to the Bosch FI book a slightly rich fuel mixture make more power and prevents pre-ignition.
When I stop for a stoplight my O2 will usually hover around .75 until the ecu works it down until it starts to cycle. In about 15 to 30 seconds I would guess.
I've never checked the O2 reading when the engine was hot and just turned off, I presume it would would be the default signal of .5v. My 85 has the 1 wire O2 sensor so it is not heated to operating temp until the exhaust gas heats it up.
Good luck
Damon Campbell <damoncampbellvw@YAHOO.COM> wrote: I am trying to nip the low power off idle/running rich thing in the bud, so i checked the idle switch (working right), sanded the ground plugs on the switches, inspected the AFM boot (medium sized crack, not a tear all the way through) and replaced the coolant temp sensor.
However, when looking at all this stuff, i noticed that the full throttle switch was loose. I tightened it back down to right spot (the digitool made that a 1 person job), but my first question is: what does this thing do? I presume it has been loose for at least a couple years, but i havn't really noticed anything wrong performance wise.
Secondly, when cruising around afterwards to see if low end power changed (can't be sure... damned intermittent problems), i noticed a couple things about my O2 readings:
1) when coming to a stoplight or such, and idling, the O2 sensor would hover around .75 and then slowly drop down to about .5v in about 30s or so. It did this several times.
2) when the car was turned off after the jaunt to fully warm it up (engine hot but not on/cranking), the sensor read .33v... eventually working up to .5v.
Do these observations mean anything? Or are they just abuse of a new toy (digitool)?
Thanks for any insight,
-Damon
'84 Westy
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