Wire AFR patern on stock ecu.
 

So I have to stock ECU in current. I was driving to work today and notice while at any rmp/speed while coursing my AFRs are going 14:7 14:6 14:5 14:4 14:3 14:2 back to 14:7. Some times it skips a step but it's going from 14:7 to 14:2 over and over as I drive. The higher the RPM the fast the change.

Anyone ever seen anything like this or know what would cause this? I feel like maybe one of the cylinders is not burning all the fuel or something like that but not sure how to test.

Sound pretty normal to me.. I also have stock ecu with wideband. It's never 14.7 for longer than half a second. It's always hunting, making small changes to fuel trims. All cars do this.

Closed loop fueling, standard feature.

MS with close loop does not hunt like this but it's also not using narrow band. Thought it might be running rich 1/4 and right 2/3 or something like that. One cylinder is not burning all it's fuel, Ect.

Thanks guys.

That's actually pretty clever for the archaic OEM engine management. Oscillating slightly rich/lean helps keep the catalyst at peak efficiency.

Market fuel does not typically have a stoich ratio of 14.7:1, despite what "common knowledge" says (before anyone asks).

As engineered2win observed, this is precisely how OEM ECUs running NBO2 sensors are designed to operate. If you run a properly-tuned MS (or any other aftermarket ECU) with a narrowband sensor, it'll do exactly the same thing.

Mazda has been doing this since at least the late 80s. 100% normal.

Agree with all, except I am concerned about your Wideband O2 sensor calibration. It should be showing the AFR going above and below 14.7.

Proper operation of ECU with Narrow Band closed loop control typically toggles from 14.5 to 15.2, or slightly rich to slightly lean. Keeps the 3-way catalyst operating correctly.

This.
I recently installed a new UEGO 30-0300 WB02 in my 02' with stock ECU, cat and NBO2 and it will oscillate between 14.5/14.6 and 15.1.

Jeff, your thread title is kind of "Wire". It took me a while to understand it.