Date:         Sat, 17 May 2008 02:06:49 -0400
Reply-To:     pickle vanagon <greenvanagon@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         pickle vanagon <greenvanagon@GMAIL.COM>
Subject:      Re: hesitation/bucking (was: Re: tested Oxygen Sensor, and...)
In-Reply-To:  <91c8f9760805162247kea69cd1td04be7065d78765a@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

Just to add to what I already wrote.

It sounds like this old post (the response part) is describing my problem
exactly (except the part about not having it for several thousand miles):
http://gerry.vanagon.com/cgi-bin/wa.exe?A2=ind9605&L=vanagon&D=0&P=145769

I didn't think of it before, but now that I read it in his description, it
seems to me that most times I have noticed the problem it has been wet
outside (for example, today!).  This could be a coincidence, though, I
guess.

Thanks again for any help!
Wes


On Sat, May 17, 2008 at 1:47 AM, pickle vanagon <greenvanagon@gmail.com>
wrote:

> Thanks for all of the responses, guys.
>
> I think maybe the first time I hadn't let the van heat up enough.  (The
> engine was already warm, but maybe I didn't actually let the sensor heat up
> enough?)
>
> When I measured again, I did get fluctuation, but the swing wasn't as large
> as .5volts.  I'd say ut swung between around .4 and .7.  I guess its
> possible that there was actually a greater swing than was showing up on my
> digital voltmeter.  I should mention: the oxygen sensor is only about 4000
> miles old.
>
> Anyways, the reason I was checking the oxygen sensor voltage in the first
> place, is that I've noticed recently (since my head job...) that the van
> occasionally exhibits some slight hesitation symptoms when driving at a
> constant speed (usually low speed, so low load).  The van surges slightly
> forward and back, maybe at a rate of once per second or so, kind of like
> very minor bucking.  It only has happened occasionally, so I can't say for
> sure when it seems to happen the most.  But it has never happened when
> accelerating or otherwise when under load, and it has never caused any
> problems idling.  It idles very smoothly, although it seems to me that it's
> idling at lower rpms than before.  Of course I don't have a tach so I can't
> say for sure.
>
> What should I look for with these symptoms?  The only things I've done are:
> looked around for any obvious vacuum leaks, checked the oxygen sensor as
> above, rechecked my valve adjustment, checked my Temp 2 sensor, and replaced
> the engine compartment ground strap (the one that goes to the head).  I'm
> guessing that with a problem like this, there's a list of 50 things to
> check.
>
> I guess I should really be checking the mixture properly in a situation
> like this, but I don't have an co meter or anything for the exhaust.
>
> Thanks for any pointers,
> Wes
> 1.9l westy
>
> On Fri, May 16, 2008 at 11:25 PM, Dennis Haynes <d23haynes57@hotmail.com>
> wrote:
>
>> A steady reading of .5 to .6 volt is a sign of an open sensor or one that
>> has not heated up enough to function. The voltage is due to the leakage at
>> the ECU input. Measure the voltage at the sensor lead with it disconnected
>> to see if you are really getting a signal.
>>
>> Dennis
>>
>>
>> -----Original Message-----
>> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
>> Of
>> pickle vanagon
>> Sent: Friday, May 16, 2008 5:53 PM
>> To: vanagon@GERRY.VANAGON.COM
>> Subject: tested Oxygen Sensor, and...
>>
>> Just for fun, I decided to go out and "test" my oxygen sensor today, by
>> which I mean I warmed up the car, and then checked the voltage coming off
>> the sensor wire with the van at idle.  I got readings of around .52 volts,
>> which maybe seems okay (?), but the voltage was steady, not oscillating
>> (it
>> stayed between .51 and .53 volts always).  Does this mean my engine is
>> never
>> entering closed loop operation?  If so, what are the standard things to
>> check, since the O2 sensor seems okay?
>>
>> Thanks,
>> Wes
>>
>
>