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2002 Hyundai Accent gl 1.6l auto trans problem

Got this little car, keeps slipping from 4th back into third. Changed input output sensors. Also common problem is there’s a couple of shims and Torrington race bearings that go back and shared in the trans… found the pieces in the trans pan when I changed the fluid and filter. I ordered the kit from WITT and slapped it on… once I got it all back together I’m still having the same issues. Anyone know of this issue and may know a solution? Thanks.

That is a small engine for overdrive. It will be shifting down under high demand. You will have to check with the dealer or manufacturer to make sure where the shift points are supposed to be.

Also, anything that cuts your engine power will make your car do this, worn out plugs, burnt valves, dirty fuel injectors or throttle body, clogged cat etc. Do you have a check engine light on?

Have you tried a proper transmission service, drain, re-fill and filter replacement? If it helps but not 100%, drive a couple hundred miles, then try it again.

The transmission shift decisions (when everything is working) is based on vehicle speed, engine load, and accelerator pedal position. so any problems with sensors associated with that could contributor (vehicle speed sensor, throttle position sensor, map or maf sensor). If all that’s working, there’s still selenoids in the transmission that could fail, and seals inside the trans could be leaking and the resultant loss of fluid pressure in certain circuits could prevent it from working correctly too. The transmission service suggested above might revive the seals, which is one reason to try it.

I do, but the codes I’m getting are p0734 / p0717… all other sensors plugs ect seem to be fine, I’m not getting any other codes besides the ones I mentioned. I’m going to change the the sensor associated with the p0707 code and do another flush and filter change and see what I come up with

The p0374 is saying there’s a problem detected with the ratio of the transmission input vs output rpms when the transmission is in 4th gear. Likely cause would be internal clutch packs slipping. The p0717 is another transmission related code, this one for the TCM’s input pulse generator (pg-a). It’s used to control the fluid pressure during a shift. Start by verifying the 4-wire electrical connector for the signal wires between the TCM and the pg-a remains in good shape