Wideband O2 Sensor w/ Bluetooth & Smartphone App

[Rosebud]

I've been searching for a wideband O2 sensor and gauge for a while. I'd given up hope finding one with a magnolia face to match the my speedo, oil, temp and fuel gauges. Besides, I like my dash the way it is; I don't need another gauge, magnolia or otherwise. I found a couple of O2 sensors that send their data to an iPhone app which seemed like the ideal solution, but they all came with a bunch of other ECU functions that I couldn't use and didn't want to pay for.

I finally found what I was looking for. This package from PLX fits the bill and it happens to be on sale at the moment.
https://www.plxdevices.com/ProductDetails.asp?ProductCode=897346002870

It comes with a Bosch wideband sensor, a compact interface box and an iPhone/Android app. It took under an hour to install and once I fired it up the lambda numbers confirmed that my carbs were dialed in and working well. Another nice feature of this package is it displays the health of the sensor. Apparently O2 sensors have a limited lifespan and the reading becomes less accurate with time. It starts out displaying 100% and lets you know when it's time to replace the sensor.

By the 2nd day my new wideband O2 setup has already proven it's worth. Yesterday (1st day) the wideband was reporting an air/fuel ratio of 15 (lambda 1.00), spot on. Today it was reading air/fuel at 13 - 14, slightly rich. I pulled the spark plugs and sure enough, they were somewhat sooty. Normally my carbs are very stable and my plugs are a nice chocolate brown... except for the time one of the chokes stuck in the wide open position. Hmm... So I reached around the back of the carb that had formerly had the sticking problem, pushed on the choke and click! The choke was stuck open ever-so-slightly; not more than a 1/16", certainly not enough to notice whilst driving. I would have never known the sticky choke was back had it not been for the wideband. Got the choke working and the A/F ratio is back to 15. Nice.

I posted this thread on another forum—so forgive me if you've already read this. Hope this is of interest to anyone considering an O2 sensor.

[94touring]

Wideband is the only way to go when tuning.   Good find on this one.

[Rosebud]

I've had my wideband for a week or so and I'd like to hear from folks familiar with interpreting wideband readings and tuning accordingly. Here's what I've got: It goes a bid lean (16-17) under mild acceleration for just a second or two. AS soon as the acceleration is over it returns to 15. Under WOT it richens up significantly to 11-13 and then returns to 15. Idle and deceleration is rich at 12-13. Does that sound about right for a fairly hot 1380 street motor w/ twin SUs? I have a 1-2-3 distributor and am fairly certain that the dwell and timing are correct. What do you think?

[94touring]

Under high load on naturally aspirated engines you typically want 12:5:1 give or take half a point for max power before detonation may occur.  Cruise ratio is perfect at 14:7:1 but can be run a tad leaner into the 15s before the car will stumble or be down on power.  Idle will usually be 12-13 to get a smooth idle.  Off acceleration or the first moment you mash the gas isn't important as readings take a moment to register.  Most of my wideband tuning has been done electronically so you can really get things dialed in, where as carbs you're limited to needles, dashpot oil, and your foot. 

[John Gervais]

Mine's not perfect, but my idle is somewhere in the low 13's, highway cruise is in the low 15's and foot-stompin' acceleration is in the low 11's - pretty much regardless of which oil I use in the carb.

I'm using the Innovate Motorsports MTX-L.

[Rosebud]

Under high load... you typically want 12:5:1. Cruise ratio is perfect at 14:7:1. Idle will usually be 12-13.

My idle is somewhere in the low 13's, highway cruise is in the low 15's and foot-stompin' acceleration is in the low 11's.

From the numbers you posted, it seems like I've found the sweet spot. Thanks for the info, guys! Think I'll leave the carbs right where they are, at least until the barometer drops a notch or two. ;-)

[94touring]

foot-stompin' acceleration is in the low 11's - pretty much regardless of which oil I use in the carb.

Oil would only effect the initial foot stomp.  If you had a dead spot when you first step on it, you'd want to thicken or thin the dashpot to richen or lean the mixture.  Low 11s is rich for NA, but ideal for a turbo.  I'd be looking at a different needle to get it into the 12s because you're leaving a lot of power on the table.  Afterall that's the beauty of having a wideband.

[John Gervais]

I'll eventually get the needle sorted, it's not too far off but since I can't add material to the diameter, I'll need to make yet another one.  Until then, though, it's better than it used to be.