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Tue Nov 20, 2012 5:17 pm

Thinking about getting a wideband AFR to tune my Vanagon....as well as my carburated projects. Looks like the much cheaper "narrowband" version would be little more useful than a voltmeter hooked up to the O2. Wideband, although expensive, seems to give much more accuracy when reading Air Fuel ratio at idle and under load. I would add another bung to the exhaust to use it.
Anybody have experience with these? What brand units do you recommend? I've been checking out units similar to this one http://www.amazon.com/AEM-30-4100-Digital-Wideband-Gauge/dp/B003ITFA9Q
There are several more that are MUCH more expensive, just curious if anybody has some input on these.

Tue Nov 20, 2012 5:51 pm

http://vwparts.aircooled.net/Innovate-MTX-L-Wideband-Oxygen-Sensor-Kit-3844-p/innovate-3844.htm

is outstanding and inexpensive IMO.

Tue Nov 20, 2012 5:58 pm

I like this stuff http://14point7.com/

Tue Nov 20, 2012 6:22 pm

[email protected] wrote: http://vwparts.aircooled.net/Innovate-MTX-L-Wideband-Oxygen-Sensor-Kit-3844-p/innovate-3844.htm

is outstanding and inexpensive IMO.
Nice write up on your site John. Still, very happy with the jetting instructions you gave me for the Progressive Weber on the 71 Westy. It would be nice to see what the AFR really is.

Tue Nov 20, 2012 7:26 pm

This is wired to my narrowband and is remarkably useful in monitoring the digifant II conversion.. You can't see the LCD "needle" in the pic but it flicks back and forth (closed loop) much faster than an analog equivalent. Mid point is .5 volts so you can observe rich/lean bias realtime. During AFM tuning I disconnected the narrowband o2 from the ECU and used a Fluke digital meter with max/min and averaging functions. On the carbureted side though (where there is no closed loop operation), there would be no substitute for wide band.

Tue Nov 20, 2012 7:28 pm

I have an autometer in the vorsche. Only went with autometer because I wanted it to match the other 7 gauges. Has worked flawlessly for the last 2 years. It is the gauge on the far right.

I also have an Innovate that I haven't installed yet. It is going in my convertible bug with a type 4 motor, megasquirt and suzuki GSXR throttle bodies. Got it from this guy. I went with the black face and red lighting. Not a bad price with free shipping.
http://www.ebay.com/itm/Innovate-LC1-Wideband-w-DB...vi-content

They are definitelty nice to have.

Tue Nov 20, 2012 10:38 pm

I have the Innovate one on my ez30

Wed Nov 21, 2012 10:23 am

I see the Inovate gauges no longer need the LC1 controller. Do they work as well?

Wed Nov 21, 2012 10:23 am

the MTX is so much better than the LC1 it's not even a comparison.

Wed Nov 21, 2012 11:27 am

I put one in my bay bus with dual dells - it similar to this:
http://www.ebay.com/itm/Lumenition-Air-Fuel-Ratio-...2ec06e2e06

about the size of a cig pack. Very useful and easily mounted with velcro. I still have it and think I am going to put it in vanagon when I install a new header/muffler.

Paul

Wed Nov 21, 2012 11:30 am

I have the aem wideband on my corrado. It works great, is reliable and accurate. I give it a thumbs up. Don't waste your time with a narrowband.

Wed Nov 21, 2012 12:04 pm

The MTX at 200 self contained sounds great. These things were 3 times the price last time i looked. Wow.

Mon Nov 26, 2012 5:43 pm

denwood wrote: The MTX at 200 self contained sounds great. These things were 3 times the price last time i looked. Wow.
I'm sold, I'll be placing an order soon.

Mon Nov 26, 2012 5:51 pm

[quote="denwood"]During AFM tuning I disconnected the narrowband o2 from the ECU and used a Fluke digital meter with max/min and averaging functions. On the carbureted side though (where there is no closed loop operation), there would be no substitute for wide band.
quote]

To tune the AFM you disconect the O2 from the ECU. Makes since. So what does the ECU see when this is done? Default mode? What would happen if one connected a .5 volt constant power source to the ECU during AFM tuning with the Wideband gauge?

Mon Nov 26, 2012 5:53 pm

Another nice thing with the MTX-L is that you can connect it to a computer for datalogging; the AEM shown can do this too. For us with the Subaru engine, Evoscan supports it so you can log ECU data along with WBo2. Cool! :idea:

Mon Nov 26, 2012 8:26 pm

Matt the ECU delivers .5v reference to the o2 sensor plug when disconnected. This is the easy way to check that portion of your harness.

The o2 sensor output is quite stable when disconnected from the ECU, however when connected to ECU the output is quite different. The ECU swings mixture rich and lean to rapidly flip/flop catalyst from oxidative to reductive state. The faster the sensor responds to this (new sensor = better sensitivity) the faster the ECU can sense it, and toggle mixture.

Assume you are driving on a flat road, steady cruise, hot engine, ECU connected to o2 sensor. If your AFM is set correctly you will see the "needle" on an analog meter bounce evenly above and below .5 volts. If your elecronic meter can average, it should read .5 volts. If it averages .4 volts, this tells you the mixture is biased lean..and the ECU is actually increasing duty cycle on the injectors more then decreasing it to achieve the maximum flip/flops above and below .5V. Based on my testing, the digifant system will idle best, perform well during cold starts and full throttle acceleration (assuming you are not doing any "interceptor" type full throttle tuning) when you've hit this .5v average. The o2 feedback system can adjust for an AFM that is incorrectly tuned when warm, however throttle response, cold starts and/or full throttle enrichment will be affected.

No idea what happens on the MTX but I'm assuming with digifant in closed loop it's averaging the reading. Obviously with carbureted systems the flip/flop deal is not happening so makes reading the output a bit more straightforward.

Tue Nov 27, 2012 2:25 pm

denwood wrote: Matt the ECU delivers .5v reference to the o2 sensor plug when disconnected. This is the easy way to check that portion of your harness.

The o2 sensor output is quite stable when disconnected from the ECU, however when connected to ECU the output is quite different. The ECU swings mixture rich and lean to rapidly flip/flop catalyst from oxidative to reductive state. The faster the sensor responds to this (new sensor = better sensitivity) the faster the ECU can sense it, and toggle mixture.

Assume you are driving on a flat road, steady cruise, hot engine, ECU connected to o2 sensor. If your AFM is set correctly you will see the "needle" on an analog meter bounce evenly above and below .5 volts. If your elecronic meter can average, it should read .5 volts. If it averages .4 volts, this tells you the mixture is biased lean..and the ECU is actually increasing duty cycle on the injectors more then decreasing it to achieve the maximum flip/flops above and below .5V. Based on my testing, the digifant system will idle best, perform well during cold starts and full throttle acceleration (assuming you are not doing any "interceptor" type full throttle tuning) when you've hit this .5v average. The o2 feedback system can adjust for an AFM that is incorrectly tuned when warm, however throttle response, cold starts and/or full throttle enrichment will be affected.

No idea what happens on the MTX but I'm assuming with digifant in closed loop it's averaging the reading. Obviously with carbureted systems the flip/flop deal is not happening so makes reading the output a bit more straightforward.
My DVM doesn't do averaging. With O2 disconected I get readings all over the place at idle,(anywhere from .3 to .7) most seem to be under .5, but it's difficult to tell for sure.
The Inovate AFR gauge is less than a Fluke VM and should give me a more exact reading. I plan to make it modular so I can tune my other machines. Should be fun.

Tue Nov 27, 2012 3:02 pm

denwood wrote: No idea what happens on the MTX but I'm assuming with digifant in closed loop it's averaging the reading. Obviously with carbureted systems the flip/flop deal is not happening so makes reading the output a bit more straightforward.

The MTX-L uses a separate sensor, a sensor which is a different technology than the 0-1V narrowband sensors. The MTX-L does have an "emulated" output that you can send to the ECU, but I just have another bung in the exhaust for the wideband sensor. And it while it does smooth the reading somewhat, you can still see the AFR moving around a bit when the ECU is closed loop, running off it's own sensor.

Tue Nov 27, 2012 3:23 pm

presslab wrote: denwood wrote: No idea what happens on the MTX but I'm assuming with digifant in closed loop it's averaging the reading. Obviously with carbureted systems the flip/flop deal is not happening so makes reading the output a bit more straightforward.

The MTX-L uses a separate sensor, a sensor which is a different technology than the 0-1V narrowband sensors. The MTX-L does have an "emulated" output that you can send to the ECU, but I just have another bung in the exhaust for the wideband sensor. And it while it does smooth the reading somewhat, you can still see the AFR moving around a bit when the ECU is closed loop, running off it's own sensor.

Roger that. Our ECU's wouldn't know what to do with a wideband reading.
Plan to put a seperate bung in the exhaust.

Tue Nov 27, 2012 5:00 pm

Understood..I realize the wideband is using a different sensor that is much more accurate outside stoichiometric. That said, installing it a separate bung won't change much if you're interfacing to digifant with it's "dumb" output.
You only need one bung, and rather than monitoring the ECU -> connection directly as I'm doing currently, you'd run one output (emulator) to your ECU, and a 2nd output to the MTX controller/gauge. Correct?