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View Full Version : Air Fuel Ratio analyzers


RicardoJM
01-23-2012, 01:50 PM
I'm really interested in knowing the exact details of how engine, ignition and fuel system perform together. To that end I've read and done lots of cool stuff; rebuilt carbs (vacuum advanced and no advance), upgraded to electronic ignition (both Toyota and GM), swapped distributors (60 series stock and Jim C. recurved), tried different jets - all with good results. That said, each time I make a change I don't really ever know how the change affected (if at all) where my rig is operating the economy/performance band Air Fuel Ratio. After making a change, I run through the lean drop tuning and move along.

This weekend I started rebuilding a weber carb and have gotten serious about monitoring AFR. With a little research, I've been able to determine there are a few ways to go about this. There are the full blown gas analyzer machines that are very expensive and then there are analyzers/gauges that use an O2 sensor. Narrow band sensors basically use the sensor display on a gauge when you are spot on the ideal AFR and if your not on ideal that you are rich or lean whereas the wide band sensors are a bit better in that they give you a better idea of how rich/lean you are. The kinds of basic things that guys used to do by reading the spark plugs. I'm not much of a read the plugs kind of guy who really wants to know more.

My truck runs great and gets about 12 mpg; sometimes more than 17 and other times less than 10. Anyhow, getting down to the reason of the post - Do any of you have any experience with using AFR monitoring tools? Things like:

Powerdex AFX (http://www.ngksparkplugs.com/products/performance/afx.asp)
Innovate LM 2 (http://www.innovatemotorsports.com/products/lm2.php)
K&N Air airfuel monitors (http://www.knfilters.com/airfuelmonitors.htm)
Homebrew setup (http://www.buckeyetriumphs.org/technical/Carbs/AFMonitor/AFMonitor.htm)

I am interested in any first hand experience that others have with this sort of thing.

rover67
01-23-2012, 02:16 PM
a narrow band setup won't tell you a whole lot other than you are over 14.7 or under it. I actually built that hombrew thing years ago BTW, from that same site. Any gauge that is based on a narrow gauge O2 sensor one won't tell you what you need to know.

Wide band O2 sensors have a nice linear change in output voltage with respect to mixture so they are much better suited to build a gauge around.

I have used the Zeitronix system with good results. I bought it a long time ago when they were the only real players...

http://www.zeitronix.com/Products/zt2/zt2.shtml


Since then there are lots more folks making them. Recently my brother got a PLX devices one that he has been really happy with.

http://www.plxdevices.com/

Whatever you get, make sure it will plug into a laptop and let you data log. That's the way my Zietronix one works. Having a log and/or watching the computer screen as you drive it basically tells the whole story right there. you'll watch the numbers change and be like "ah ha!". you can also get ones with gauges..

Matter of fact, Bruce was using my wideband for his dirt bike. If he's done with it you are welcome to borrow it. You'd just have to weld an o2 bung into your exhaust, throw in the sensor, and give the box it comes with 12 volts. Hook it up to a laptop and viola!

rover67
01-23-2012, 02:23 PM
BTW, here's a page on the Zeitronix site that shows how it can have a offset output to mimick a narrow band o2 sensor at a richer or leaner setting. Useful if you want to trick a fuel injected car into running lean or rich, but not too much for you since you are carbed.. what it does show is a graph of the sensor output though.

http://www.zeitronix.com/questions/NBpoint.shtml

wide band output is nice and linear.

Red_Chili
01-23-2012, 02:33 PM
I run this. Of course with an EFI motor it sweeps a fair bit. You might enjoy the visual entertainment, and learn what happens at full throttle, high altitude, etc...

http://cdn.autoanything.com/images/products/rell/performance/aem_wideband_uego_air_fuel_ratio_digital_gauge.jpg

Uncle Ben
01-23-2012, 02:36 PM
Unless you're just wanting flashy blinking lights to impress your friends what you need will cost a few pesos. You need to data log! You can get several good hand held loggers that really are awesome but they will cost you in the $500ish range. I suggest researching a bit and obtaining software for your laptop along with a serial cable. You will need to weld in a O2 sensor bung as close as possible to where your exhaust becomes a single stream. Often you can find freeware and serial cables can be often found where you find the freeware and even ebay. The cable will have the data cable hook up for your laptop and two "free" wires that will be hooked to your Cruisers battery along with a inductive clamp for #1 plug wire. (for the wideband O2 sensors heater) That is the cheapest way to go. If you don't data log you will only see snapshots of whats going on and not have a complete "map." The more you spend and the more data you acquire in your log will show you load vrs. rpm vrs. fuel pressure vrs. ambient temp vrs. altitude vrs. timing vrs. manifold temp vrs. etc.... Oops guess we just converted you to OBD fuel injection....

rover67
01-23-2012, 03:06 PM
I run this. Of course with an EFI motor it sweeps a fair bit. You might enjoy the visual entertainment, and learn what happens at full throttle, high altitude, etc...

http://cdn.autoanything.com/images/products/rell/performance/aem_wideband_uego_air_fuel_ratio_digital_gauge.jpg

those are good to let you know if your o2's are switching or if it is running open loop.. and that's about it :)

60wag
01-23-2012, 03:06 PM
Marco's Zeitronix is pretty easy to work with. I plugged it into a laptop and road around with the laptop in my backpack. It definitely helped to get the jetting dialed in.

RicardoJM
02-06-2012, 05:15 PM
... If he's done with it you are welcome to borrow it.

I appreciate the offer Marco but went ahead and ordered the unit. I don't know if I'll get the O2 bung in by this weekend, but if I can you can bet I'll fire it up at the CM wrenching session:D.