Can oxygen sensor trigger bad shifting?

[penz08]

I had the transmission on my 2018 Mazda3 changed around six months ago. Was running perfectly fine till recently.

Seems to be upshifting right, but downshift or passing a car, the engine seems to choke and slams into a hard downshift, seems to be 3rd and 5th gear (I have the automatic). This creates a kind of jerking slightly.

Now, with a new transmission recently installed, I suspect it could be the upstream oxygen sensor. I have no code, no CEL, nothing. Spark plugs have around 50k km on them, air filter is good. Seems to lack power and have lower MPG, smells like gas sometimes on startup.

Is it possible the transmission is going out again? or a lazy oxygen sensor would be the cause?

Anyway, I'm tired of the trouble I had over the last year with this car, I have a deal to get rid of it and get into a 2023 Civic Sport with CVT.

Any tips would help, thanks.

 

[flash7210]

O2 sensor should set a code.
Some scan tools can read the live data from the O2 sensor.
I use the torquePro app on my phone for this.

I don't think it's transmission

I'd start by checking for vacuum leaks.
PCV/breather hose connection.
And it never hurts to do a throttle body cleaning

 

[Trav]

Engine performance issues can certainly feel like something is going on with the transmission. Time for a scantool to dive deeper into it, no guessing and no parts cannon.

 

[oldhp]

Put it up on a rack and check all the wiring that had anything to do with changing the transmission. A wire or wiring harness could've got pinched, pulled apart or laying on exhaust and finally burned thru.

 

[penz08]

Engine performance issues can certainly feel like something is going on with the transmission. Time for a scantool to dive deeper into it, no guessing and no parts cannon.

its seems like the same downshifting problem that I had before with the old transmission, into 5th and 3rd gear. Mazda actually put out a bulletin for this issue, I wonder if its just the TCM, if they ever changed it.