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Date:         Sat, 27 Jun 1998 17:58:33 -0500
Reply-To:     Darrell Boehler <midwesty@TAOS.MIDWEST.NET>
Sender:       Vanagon Mailing List <Vanagon@vanagon.com>
From:         Darrell Boehler <midwesty@TAOS.MIDWEST.NET>
Subject:      Re: new O2 installed - engine dies
Comments: To: Vanagon@VANAGON.COM
Content-Type: text/plain; charset="iso-8859-1"

-------------------------- Hi Michael , Sorry I make an error please make this correction. The voltage measured at the oxygen sensor with it connected is 0.5 volt not 0.0 volts at initial start up. This is important difference sorry for the screw up.

Also if you want to build yourself a digifant tool I have posted instructions at

http://taos.midwest.net/vw

Darrell Boehler Makanda Illinois

-----Original Message----- From: Darrell Boehler <midwesty@TAOS.MIDWEST.NET> To: Vanagon@VANAGON.COM <Vanagon@VANAGON.COM> Date: Saturday, June 27, 1998 5:23 PM Subject: Re: new O2 installed - engine dies

>----------------------- >Hi Michael , > Let me explain by giving you some meter readings from my 86 digifant / >oxygen sensor and maybe you can discern where your problem is. All readings >will be from frame or ground. > Lets start by disconnecting the oxygen sensor , with the key on, the >wire from the oxygen sensor connector to the digifant pin 2 reads 0.5 volts. >With the engine running this wire will still read 0.5 volts . You can drive >around all day and it will read 0.5 volts. This is the norm. > Now lets meter the wire from the oxygen sensor. Still with oxygen sensor >wire disconnected from the wire that goes to the digifant. With the key on >the voltage will be 0.0 volts until we start the engine. Once the exhaust >starts to warm the oxygen sensor, aided by the internal oxygen sensor >heater, the oxygen sensor will start to produce a voltage output. The >amount of that voltage will depend on how rich your mixture your digifant >producing for your engine in default mode. Note we will be in default mode >until the oxygen sensor produces a voltage to the digifant for about 30 >seconds. Since we are disconnected the digifant will not see a voltage from >the oxygen sensor and will stay in default mode. My oxygen sensor voltage >runs at 0.0 volts for 0.5 to 1 minute , depending how hot the sensor is >before starting the engine. If it were very cold it would take longer than 1 >minute. After 1 minute the voltage climbs to to 0.9 volts and stays there. >The oxygen sensor is getting a pretty rich reading in default mode, my van >seems to run ok in this mode but mileage would not as good as normal. > With the van still running if I plug the oxygen sensor connector back >together the voltage reading will stay at the 0.9 volt level for 30 seconds >. Then the digifant has discerned the oxygen sensor is working and has is >detecting a rich mixture and by 35 seconds my digifant has the oxygen >sensor voltage readings bouncing above and below the 0.5 volt range. 0.5 >volts reading indicates a perfect mixture. The bouncing of the oxygen >sensor voltage above and below 0.5 volts is the way all ECU's seem to >operate. > With it connected if I observe my oxygen sensor voltage starting from a >warm stopped engine. My reading is 0.0 volts for about 30 sec. 0.9 for

--------------------------------------

NOTE :

This should be , My reading is 0.5 volts here for about 30 seconds.

>exactly another 30 seconds and then I get the rapid fluctuations as the >digifant takes the con. > Your reading in default mode may be less than the 0.9 volts I read but >it should be above the 0.5 volt area. Hope this helps and good luck with >your van. > >Darrell Boehler >Makanda Illinois > >-----Original Message----- >From: Michael Sullivan <sullivan@OPENMARKET.COM> >To: Vanagon@VANAGON.COM <Vanagon@VANAGON.COM> >Date: Saturday, June 27, 1998 2:40 PM >Subject: new O2 installed - engine dies > > >>Dear List, >> >>I finally got around to installing a new 3-wire O2 sensor (generic from Ron >@ Bus Depot) on my 87 Westy Syncro. Splicing was done properly (soldered w/ >heat shrink). Car started normally. Once warmed up however, engine lost all >power, couldn't even keep an idle. Short story: I had to disconnect my new >O2 sensor to get back home. >> >>So, this makes me think that the old one was, in fact, bad and that the >PO's mechanic simply adjusted the car to run "ok" with a bad O2 sensor. Am I >right? (note: gas mileage wasn't all that great before -- 15mpg -- and >horsepower was adequate but not as good as another Vanagon owner's car which >I have driven). >> >>Or is it possible that the new O2 sensor could be bad? >> >>I tried getting a reading from my DMM but I couldn't get a steady reading >at idle. Another thing: engine now (with no O2 sensor) idles steady - no >1-second fluctuation between 900 and 950rpm. Also, if I pull off the vacuum >hose to the fuel pressure regulator, nothing happens, even leaving the hose >sucking air into the engine. Does that mean my engine is now running ruch? >> >>I noticed quite a few threads on this subject in the archives, but I could >not find a lot of actual answers/solutions. Any help would be greatly >appreciated. >> >>Cheers, >> >> >>Michael J. Sullivan >>Director of Catalog Design >>Open Market, Inc. >> >>'87 GL Syncro Westfalia >>******************************************** >>work: http://www.openmarket.com >>vanagon: http://www.hsdesign.com/vanagon >>scan tips: http://www.hsdesign.com/scanning >>******************************************** >> >


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