| Author | Message | ||
     Ryker77 |
This is the second A/F gauge I am trying. Its brand new. With only 12v power supply and ground wire. The gauge shows full rich 1.0+ volts. From what I've read the A/F gauge is just a volt meter it reads the volts from the 02 sensor and displays them. But I don't have the 02 sensor wired up, so why does it show full rich? I sent the first one back to autometer and it was sent back "tested OK". So I tried another new one.  The first A/F gauge mostly stayed on the rich setting and sometimes would bounce around when riding the bike. | ||
| Blake |
Full rich would correspond to 0.0 volts. Only the presence of oxygen will generate a voltage in the O2 sensor, thus the lack of a voltage indicates no oxygen a rich condition. Not sure what you mean by "full rich." Best take a look at Al Lighton's report on O2 sensor behavior. It is in the Knowledge Vault somewhere.  | ||
| Opto |
Some guages will do that. Try grounding the wire that's supposed to go to the O2 sensor and it should show full lean (0V). On my XB12S 04 at cruise the stock O2 sensor voltage bounces up and down continually, and at decent throttle openings the O2 sensor puts out around 0.82 volts (approx 13.5:1 AFR) | ||
| Shotgun |
What Opto said, Blake is backwards. Full rich is 1.0, full lean is 0.0. The X1 stock sensor is not the best either. I think Aaron and others go with a more sensitive unit. | ||
| Ryker77 |
I emailed both autometer and a guy that converts A/F gauges to stop the bouncing. Its normal for the A/F gauge. | ||
| Al_lighton |
The article Blake referred to is at http://www.badweatherbikers.com/buell/messages/3842/16109.html?1119198783. The output response curve of the O2 sensor shown in that article is:  Seems to me that the last thing you want to do is get rid of the bouncing, though I could see how a little bit of smoothing would be helpful. It isn't the meter doing the bouncing, it is the voltage output of the sensor itself. From .25 to .65 volts it's all at 14.7:1 or so. A tiny bit above APPROXIMATELY .65V is slightly richer, a tiny bit below APPROXIMATELY .25V is leaner. But the exact voltage is meaningless with a narrowband sensor, they aren't calibrated well enough to look at any output voltage and infer a specific A/F ratio other than 14.7:1. All you really know is that if the meter is bouncing all over the place, you're at 14.7:1, and that if it is starting to bounce less at the high side, you're at the knee of the curve and are starting to drop your A/F ratio below 14.7:1. Heck, if the O2 sensors were sensitive enough to indicate actual A/F ratio, then the ECMs would probably just run in closed loop all the time. The trouble is that even if they were that well calibrated when new, age, exposure, and temperature all throw the output response off. That strong non-linearity at 14.7:1 is no coincidence, it was designed in to that cars don't need to get their FI systems calibrated every 6 months. The FI systems vary injector duration to maximize the .45V crossings, pretty much ensuring that they are at 14.7:1. | ||
| Opto |
My post above was too brief, obviously... Some guages will do that. meaning some A/F gauges will read full scale with no input signal, this is normal. On my XB12S 04 at cruise the stock O2 sensor voltage bounces up and down continually meaning this is what narrowband O2 sensors do normally, unless there is something wrong with your Buell and at decent throttle openings the O2 sensor puts out around 0.82 volts (approx 13.5:1 AFR) meaning when the narrowband O2 on my bike puts out a steady 0.82V the AFR measured with an onboard wideband sensor is approx 13.5. | ||
| Ryker77 |
Al, the guy I was talking about changes the gauge so that it only reads the a small portion of the actual range. So that when at full throttle you can actually see the correct a/f ratio. let me see if I can find that website again.. | ||
| Ryker77 |
We recalibrate the gauges to the narrow O2 voltage range that your vehicle should run while at full throttle. The finished product has 5 times the resolution of the stock gauge and incredible speed and accuracy. On the modified gauge, each of the 20 LED's will represent .01V covering the range from approximately .78V to .98V. This range covers full throttle conditions in most vehicles. The modified gauge will no longer display the lower air/fuel ranges seen at idle and while cruising. http://www.gadgetseller.com/gauges/index.htm | ||
| Al_lighton |
That actually sounds useful, though I personally would probably want it to go a little lower than .78V to pick up some of the 14.7:1 section of the curve. That is important, because it isn't the absolute voltage that you care about, it's the meter ballistics. You need to know when you've transitioned off the bouncy readings to a more steady reading, and .78V seems a bit high for that. Anything below .6V is meaningless for how we want our engines to run. | ||
| Ryker77 |
I'm sure the guy can wire it up any style you want. That WOT guage might be usefull in onetime tuning. But for real road use I can't be looking at a gauge while on a public road at full throttle. |
