2012 Mazda5 Intermittent Upshift issue

[n2gadgets]

I have a 2012 Mazda 5 with 125k, automatic. The car runs and shifts great most times. No hard or slipping shifts. Once the engine is warm, on occasion, it will not automatically upshift when taking off from a slow down or after downshift when passing. I can use the manual shift to get it to upshift and it again works fine. This doesn't happen every time is these situation but maybe once per trip. I have never got a code or engine light. I know the TCU has a poor location and should be relocated but without a code, can it be the problem? Is there another sensor that may be causing my problem? Fluid level is fine and last change for it and the filter is unknown. Any suggestions?

Thanks,

Doug

 

[mofotech]

Is it like .. its just driving slow and not shifting? I would check your spark plugs. Also I had the TCU issue and ended changing it and alot of actual slipping issues I had went away.

 

[n2gadgets]

Spark plugs are good. Looks like I will try the TCU even though I get no codes.