Fuel air Monitor

[excess11]

I found this item in the Chaparral catalog and thought it could be useful in jetting carbs (Link at bottom of page). The price is very high though. It does not look that hard to build one. It uses an oxygen sensor and a guage that measures resistance. I am pretty sure that a O2 sensor works by measuring resistance so a ohm meter could be used for the readout. Maybe someone with a backround in electronics would be able to make a functioning unit. This could take the guess work out of jetting.K&N FUEL AIR MONITOR

[LoserShoes]

Been thinking about something like that, don't know enough about 02 sensor at the moment to comment, but will do some research and get back.

Steve

[LoserShoes]

Ok, the short answer is - no it's not that easy.

The long answer is that there are two types of O2 sensors, narrow band and wide band. The narrow band put out a voltage signal, but over such a narrow range that it's more of a switch then a sensor.

The wide band sensor work with a constant voltage/varible current scheme. The ratio is porportional to the current. It has a niece wide range, but requires a microcontroller running a PID algorithim to control the current to maintain a constant voltage across the sensor.

Not really a difficult thing to put together if you have some microcontroller experiance, but not as simple as reading it with a meter.

Steve

[mainlylinux]

for something cheaper than a wideband O2 sensor but better then a narrow band try a EGT sensor.

Dan

[Gr8Cook]

I don't know very much about wide band o2 sensors and haven't worked with them.

The standard o2 sensor is NOT read by an ohm meter. It is read by a digital volt meter. When heated to about 300C these o2 sensors generate voltage in the ABSENCE of oxygen. They generate a voltage between .05V and 1V with .05V being very lean and 1V being very rich. The Stoichiometric air/fuel ratio (14.7:1) is around .45V. I have found them to be a reasonably good tool for carb tuning on cars and trucks. You get an idea of what the different circuits are doing at different RPM and vacuum readings.

DISCLAIMER: I HAVE NEVER TUNED A MOTORCYCLE CARB

That said it seems to me that you want to get a reading on each cylinder but I suppose if the plugs look the same you can adjust the carbs as a group.

Might not the ColourTune be a good option? I've never used it but it looks sweet.

Cook

[Gr8Cook]

More 02 sensor info:

http://www.airfuelmeter.com/english/lsu4_en_sensor.htm

Wideband setups:

http://www.zeitronix.com/Products/zt2/zt2.htm
http://www.micro-craft.com/english/

Narrow band voltage/(A/F) graph:



If you want to get crazy about it:

http://ls1edit.slowcar.net/o2volts.htm

Hope this helps.

Cook

[Trikerneil]

Have you guys seen THIS DIY fuel/air monitor. Looks like an interesting project

[Trikerneil]

Gauges HERE and HERE

[Trikerneil]

The LM3915 chip in the above link is no longer available here are a few that use the LM3914 LINKY