Date: Mon, 10 Sep 2007 22:29:39 -0700
Reply-To: Michael Elliott <camping.elliott@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Michael Elliott <camping.elliott@GMAIL.COM>
Subject: Re: My poor MPG, O2 sensor seems okay
In-Reply-To: <0JO6002V1QCIP1V2@vms048.mailsrvcs.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Hm. Well, I haven't noticed any loss of power. I have a "reference" drive:
a climb from sea level up to about 7,000 feet which we take a couple times
a year to a favorite campground. The van seems to pull up the grades at
about the same rate as it has from the beginning.
--
Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
KG6RCR
On 9/10/2007 8:43 PM pdooley wrote:
> The value is having something to reference.
> However it looks like you are already past this point in your diagnostics.
> I thought you needed to know since you indicated the scope results wouldn't
> mean anything.
>
> If your compression is low enough to kill your fuel mileage you would
> probably experience a noticeable loss if power, but maybe not if the
> progression was gradual.
>
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> Michael Elliott
> Sent: Monday, September 10, 2007 10:51 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: My poor MPG, O2 sensor seems okay
>
> I'm not certain what the value is in doing that. Mellow Yellow handily
> passes California emissions testing so I know it's not running rich or it
> would fail hydrocarbons. And the output of the O2 sensor, sitting as it
> does right around the nominal value without going very high (rich) or very
> low (lean) suggests that the ECU is getting useful measurements and is
> managing to keep the mixture right around stoichiometric combustion. It
> seems to me that if the engine was running so rich that it would be
> causing the considerably poorer mileage than what others report (and I
> don't lead-foot it), then I would expect to see a darn rich mixture all
> the time and not expect to have to examine the minutiae of the O2 sensor's
> output to see some hidden richness.
>
> At this point I'm pretty convinced that my fuel is not blowing out the
> tailpipe unburned -- it ain't black, the plugs aren't black, the exhaust
> never smell rich. I'm moving on to check compression.
>
> --
> Mike "Rocket J Squirrel" Elliott
> 71 Type 2: the Wonderbus
> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
> 74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
> KG6RCR
>
>
>
> On 9/10/2007 7:38 PM pdooley wrote:
>
>> Mike, do you have another vehicle with good O2 sensor?
>> Just scope that one and compare.
>>
>> -----Original Message-----
>> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
>> Michael Elliott
>> Sent: Monday, September 10, 2007 9:22 PM
>> To: vanagon@GERRY.VANAGON.COM
>> Subject: Re: My poor MPG, O2 sensor seems okay
>>
>> Hi Mark
>>
>> I know about meter sampling rates. I grew up with analog meters and really
>> miss how good they were for showing changes in voltage or current whereas
>> digital meters are piss-poor at that but much better at displaying values.
>>
>> I could easily hook up the scope, but unless I know what a normal rate of
>> bounce and range of bounce are, the results won't offer much
> enlightenment.
>> --
>> Mike "Rocket J Squirrel" Elliott
>> 71 Type 2: the Wonderbus
>> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
>> 74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
>> KG6RCR
>>
>>
>>
>> On 9/10/2007 6:02 PM Mark Drillock wrote:
>>
>>> Mike, the voltmeter approach depends on the sampling rate of the meter.
>>> Using a scope instead gives a more real time reading and also a good
>>> indication of the cycling rate at which the O2 reading goes from rich to
>>> lean and back again. Ken's monitor is good for this as well and much
>>> cheaper besides. Some of us have scopes already so we get to have more
>>> fun than most, if we care to.
>>>
>>> Mark
>>>
>>> Michael Elliott wrote:
>>>
>>>> Hi Kenneth, I got one of your O2 sensor monitors a couple weeks ago and
>>>> did a quickie clip-lead hookup to the sensor this afternoon in addition
>> to
>>>> looking at the voltage with my DVM. The monitor works as advertised, a
>>>> good deal for a measly 20 bucks, and the little bouncing dot is fun to
>>>> watch. On Mellow Yellow it mainly ranges one or two bars above and below
>>>> the center bar, maybe spending a little more time on the center bar,
>> which
>>>> I presume to mean that on the average the mixture is neither too rich
> nor
>>>> too lean.
>>>>
>>>> I can confirm that Mellow Yellow exhibits the same behavior as your web
>>>> page describes, viz:
>>>>
>>>> 1> When the engine is first started the Dot * "floats" in the middle of
>>>> it's range. (DVM says about .35mV at first)
>>>> 2> As the engine/O2 sensor starts to warm the Dot creeps towards rich.
>>>> (Yup -- slowly climbs to about .45mV).
>>>> 3> When the ECU switches to closed loop operation the Dot swings back
> and
>>>> forth rapidly. (Yup, centered around .55mV. Mark Drillock suggested
>>>> hooking my scope to the sensor to see how exciting it truly is. I'm not
>>>> sure I'm ready for that much excitement!)
>>>>
>>>> I have not tested full throttle to see if my sensor reacts like your
> next
>>>> step: "4> At full throttle the Dot stays pegged in the rich zone," which
>> I
>>>> will do tomorrow.
>>>>
>>>> With regard to your Step 5 "An old O2 sensor caused the Dot to jitter
> and
>>>> move lazily as opposed to a new sensor which gave crisp and rapid Dot
>>>> movement from one end to the other." I can say that the dot here bounces
>>>> around in quite a lively fashion with no laziness observed.
>>>>
>>>> Mark suggested that I take the van out onto the highway and see what the
>>>> monitor reports. This is a good idea since highway driving is about 95%
>> of
>>>> my driving this should give me an indication of whether my poor gas
>>>> mileage is because it's all going out the tail pipe.
>>>>
>>>> The "Here is a good link O2 LINK" link on your page is broken, BTW.
>>>>
>>>> --
>>>> Mike "Rocket J Squirrel" Elliott
>>>> 71 Type 2: the Wonderbus
>>>> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
>>>> 74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
>>>> KG6RCR
>>>>
>>>>
>>>>
>>>> On 9/10/2007 5:12 PM Kenneth Lewis wrote:
>>>>
>>>>> Mike,
>>>>> If you read the tech sheets there is more to a "good " O2 sensor than
>>>>> voltage swing. They talk about "slow" sensors also. I have some info
>>>>> (plus
>>>>> my O2 sensor monitor) on my website : http://neksiwel.20m.com/
>>>>> Ken Lewis
>>>>> /
>>>>>
>>>>>
>>>>> ----- Original Message -----
>>>>> From: "Mike "Rocket J Squirrel" Elliott" <camping.elliott@GMAIL.COM>
>>>>> To: <vanagon@GERRY.VANAGON.COM>
>>>>> Sent: Monday, September 10, 2007 6:47 PM
>>>>> Subject: [VANAGON] My poor MPG, O2 sensor seems okay
>>>>>
>>>>>
>>>>>> As I've posted previously, my 84 1.9L auto only gets about 15.5 MPG
>>>>>> while others have reported somewhat higher mileage. Even after
>> filtering
>>>>>> out those who seem to be quite optimistic, and paying especial
>> attention
>>>>>> to those who deny not keeping careful records, Mellow Yellow still
>>>>>> trails the pack. It gives us great sadness.
>>>>>>
>>>>>> It has been proposed that my poor numbers might be due to a funky O2
>>>>>> sensor, or crummy compression. I'll get to the compression tomorrow or
>>>>>> the next day, but right now I have hooked up my handy-dandy voltmeter
>> to
>>>>>> the sensor and with the engine warmed up, it is outputting between .36
>>>>>> volt and .66 volt, ranging around about .55 volt. This seems kinda
>>>>>> normal, from what I read.
>>>>>>
>>>>>> --
>>>>>>
>>>>>> Mike "Rocket J Squirrel" Elliott
>>>>>> 71 Type 2: the Wonderbus
>>>>>> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
>>>>>> 74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
>>>>>> KG6RCR
>>>>>>
>>
>
>
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