Date: Mon, 10 Sep 2007 18:22:28 -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: <46E5E943.7060500@cox.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
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
>>>>
>>>
>
|