Closed-loop O2 Control, Wideband and Narrowband Input

Breaking news March 7 2020!
As of this week we have working O2 control (closed-loop mode)!

Wideband input is now functional. The air/fuel ratio setpoint (lambda, actually) is configurable in Airtune. After startup and once the oxygen sensor warms to temperature, the ECU is now able to maintain the mixture at/around that designated setpoint value. It’s working, but needs a good deal of tightening up. Narrowband support will be following in the next few days.

I was originally planning on developing closed-loop operation well after launch, with only open-loop fueling methods supported starting out. But was convinced to go ahead and get it done now. Seeing it operating first-hand I feel that it’s well worth the effort. Watching the ECU run the engine all on its own with no human input… that’s something special. It’s like the first time realizing that your baby is growing up :joy: :sneezing_face:

Wideband review: I’m using the 14point7 Spartan 2 wideband kit, and very satisfied so far. I feel that it’s a great value at $125. Sensor included, but no external gauge because we have Airtune w/ gauge & graphing.

I love the product and the obvious amount of work Alan (developer and owner, I can relate) put into developing a well polished device at a low price point. I’m a fan of the inline design. Looks and feels like it’s just a cable. Easy to tuck away for a clean install.

My only disappointment is the shipping speed and my perception that Alan may have burned out a bit somewhere along the line (I understand that). The “fire” just seems to be missing. I don’t know, just my impression from a thousand miles away. In any case, I wish him and the company well and will surely buy more down the road as long as I don’t need one right away.

However, the next wideband kit I plan to try out (whenever it’s needed) is the Innovate #3877. It’s priced a dollar and some cents less than the Spartan 2 now. I’m particularly interested its “DirectDigital” response time claims. If you have some time to kill, you can read up on that here.

That’s the news for this week. Questions, comments? If you like these smaller/more frequent updates want to see more, be sure to hit the :heart: below and leave a comment with your thoughts!


Update: I didn’t even last until morning :rofl:

Reading this section of the DirectDigital write-up again just now threw the hook in:

Injector balancing. OEMs allow up to 5% cylinder-to-cylinder variation in new fuel injectors. This is less than ideal to begin with, as some cylinders will be lean (producing excessive NOx), and some will be rich (producing excessive CO). The real problem however, is that this condition deteriorates over time (injector clogging, etc.). Cylinder-to-cylinder variation climbs to 10% or more, stressing the catalytic converter, damaging engines, and producing excess emissions. Direct Digital technology is fast enough to enable a single sensor to detect individual-cylinder lambda as the “slugs” of exhaust pass the sensor. This allows the ECU to vary each injector’s duty cycle, and precisely manage each cylinder.


So that settles it. It’s going on the Polaris Ranger 800XP build.


Yes. This is exaclty what is needed, an accurate closed loop system.
To me, this is the icing on the cake, and will make for a very good efi system.

Al! :wave: Welcome to the new forum, thanks for coming over.

I’m excited about it, although I’d been set on supporting open-loop only for a while. It’ll be good challenge implementing an auto-tuning process. For now, I’m planning to run an 8x8 AFR table on the Ranger 800. RPM versus load.

Sounds good.
I know there are so many other variables to add to the complexity, spark tables, map tables, etc.
All out of my league, sounds like you are all over it.
Looking forward to seeing nano efi out in the wild.


Just a quick catch-up/follow-up. The Innovate wideband kit arrived fast, had it on my doorstep within two days with Prime.

I have to say… as happy as I am with the 14point7 kit. I’ll admit that I’m a good notch or so more excited to get started with the Innovate controller. The DirectDigital feature, on paper at least, appears to be awesome.

Stay tuned, more to come.


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That’s great news.
So I started out my journey looking at the aliexpress kits and I read they don’t support wideband O2 sensors and therefor can’t support closed-loop auto tuning capabilities. So I started looking for something that could do this and I ended up here, this makes me very happy!