Air fuel ratio meter

// April 8th 2008,
Last time I wrote here was Oct 9th 2007. I wrote about a link tidy up, needed and maybe now too. However, I hope to soon provide more info about more air fuel meter types. Also now I have added just a little.

From Oct 9th 2007:
Sofar I haven´t included any wide band section. Unless the demand is for pecise tuning, narrow band meters give a general eye on the fuel situation but I still don´t understand why as it seems, all meters only measure linearly.
Anyway, I have been very occupied with other web site projects but this one is among the first ones I did and put some time on, the design is pretty simple. //

I guess I could say something more about the subject, but what, there are thousands of pages out there! Wide band meters are interesting as well. I think I add some pages. Here are some more links on the subject of afr-s.

Since the introduction by Volvo in 1976, all cars became factory equipped with narrow band oxygen (O2) sensors as a part of their engine system. In order too see that it works properly in time, the status of the O2 sensor can be checked. Normally, it will last for quite a time unless there is something wrong. That is maybe the prime purpose of these meters in order to maintain a good car performance. Apart from fuel economy, emissions are also kept lower resulting in a better exhaust system.

With a narrow band sensor, the stoichiometric point, lambda ≈ 1, can be known quite for certain. This is, because the stoichiometric mixture corresponds to voltages around 450 mV, almost independently of the exhaust temperature. So, anything between ca 200 - 700mV is within the stoichiometric area. These values may vary in different articles and reality. Also depending on the condition of the sensor.

Usually, most 10-led meters have a 100 mV scale resolution. Since lean operation can be risky, the lean leds should be red. And as seen in the gallery page, they are, though not in adequate overall accordance.
A led color design that would relate to the unlinear output of a o2 sensor as described on the gallery page could be;
Lean - led 1 (and maybe 2).
Lambda ≈ 1-area - led (2,) 3, 4, 5 (and 6).
Rich - led (6,) 7, 8, 9 and 10.

But as you can see in the gallery page, none of the meters have that.

The electronics inside these products is generally very alike. Some may have some input protection, polarity protection and some may have a diffential/balanced input (which can be discussed in regards to the floating earth in a car). One or two have an automatic dim function.
Some are more popular, maybe also due to a ((sub)conscious) influence by design.

There are many cars and vehicles using more than one O2 sensor and a dual channel air fuel meter should gain interest. However, it doesn’t seem to be anyone to find?



External links.

Wikipedia - Air-fuel ratio meter

Wikipedia - Air-fuel ratio

A page more dedicated to the Nordskog equipment.
http://www.chevyhiperformance.com/techarticles/53159_nordskog_budget_air_fuel_meter/

Pages with ready made search links for air fuel ratio meters by means of having all the various phrase terms to search efficiently.
http://www.air-fuel-meter.com

Another short words about air fuel ratio.
Air fuel ratio - Motorsportworld.co.uk.

An example of installation and use is given here.
http://www.jetlink.net/~okayfine/su/airfuel.html

Info about the LM-1 wide band meter.
www.kennedysdynotune.com/AFR Meter.htm