Date: Sun, 20 Jan 2002 15:26:13 -0800
Reply-To: Ed DeBolt <eddebolt@SOFTCOM.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Ed DeBolt <eddebolt@SOFTCOM.NET>
Subject: Re: Continued Bucking - Digifant readings
Content-Type: text/plain; charset="iso-8859-1"
My van runs well but the 02 sensor readings via digitool have always puzzled
me. the sensor will fluctuate between .2 and .7+ and here is what I don't
get. I also see a negative number between these fluctuations. usually -.2 or
less. It seems to do this rhythmically. .8~ then .2~ and then this negative
reading then back to the .2 to .8 range. seems to do the negative reading
consistently.
any ideas? my van runs great but darrell did not think a negative number
should ever be present.
ed
-----Original Message-----
From: David Beierl <dbeierl@ATTGLOBAL.NET>
To: vanagon@GERRY.VANAGON.COM <vanagon@GERRY.VANAGON.COM>
Date: Sunday, January 20, 2002 2:21 PM
Subject: Re: Continued Bucking - Digifant readings
>At 04:52 PM 1/20/2002, van man wrote:
>>Throttle switch led and Fi led work correctly when
>>idling and wide open.
>>temp 1 - hovers around 1.24/5 up to 1.28 once
>
>Air temp, seems reasonable.
>
>>temp II - hovers around .14/5
>
>Engine temp, seems reasonable.
>
>>OX - fairly wild, occasional - to 6.3
>
>Should be bouncing around, but never over a volt. If it's actually going
>to six volts, prolly a leak to the heater leads inside the sensor.
>
>>AFM - around 3.5 - couple of checks showed 3.8/9
>
>Should vary roughly linearly with throttle opening, up to somewhere near
>five volts. It actually reads the AFM position, so constant throttle with
>changing engine speed will give a changing reading, but you should be able
>to make it follow your foot short-term.
>
>
>>When the bucking was occuring, numbers seemed to hold
>>steady, although FI light flicked on and off wildly.
>
>That would certainly cause bucking...light should flash for each injector
>pulse, at running speeds looks continuous.
>
>>Also, battery level down to low 11's during bucking,
>>even 10.9. still bucked a time or two at battery
>>level of 12+, but when bucking was bad, battery level
>>was always in the 11's.
>
>Bingo. Bad ground somewhere, or possibly bad supply voltage to ECU. That
>voltage is what the ECU is seeing, not what the battery is
>delivering. Careful study of Bentley might show exactly which ground is
>the main candidate.
>
>The main weakness (as well as one of the strengths) of the Digitool is that
>it depends on ECU ground for its ground reference. Bearing that in mind,
>you can use its external probe to look at various grounds. The *most
>negative* reading you find is the "best" ground. Ideally it should be
>very close (millivolts) to the negative battery terminal.
>
>david
>
>
>--
>David Beierl - Providence, RI
> http://pws.prserv.net/synergy/Vanagon/
>'84 Westy "Dutiful Passage"
>'85 GL "Poor Relation"
>
|