Hey guys I have a hummer h3 around 87k miles. When I am driving on the highway let’s say going 80 at the same speed the rpm will be like going from 3 to 2500 back to 3 and like bouncing it happen and been noticing it a lot when I am going fast on high rpm it will be bounce specially if I am in the same speed. I did a research some said might have low trans fluid I did a fluid change and made sure it’s not low but it still does it.. anyone got an idea? I just start noticing it recently

 

Opposite for a trans, rpms would increase. What gasoline are you using?

 

93. Everything I use is the same it just recently started :/ and it doesn’t happen all the time but i notice it more. What might be the cause of it ?

 

Your Trans is cycling between full lock up (OD) and Third and might be on its way to a rebuild. Did you change trans fluid and filter?

 

yes I did. The car runs fine and shift fine it’s just this at certain speed . Not sure why

 

Does it do the rpm change when the Hwy is flat? Or only when there are some rolling hills?

 

I think mostly hills or inclines. I haven’t seen it so much for flat as far as I remember

 

RPM's would increase on an incline to maintain mph.

 

but it increase and decrease back and forth every few secs

 

You need to clarify, what are your RPM'S cruising @80MPH(OD locks in around 50mph)? 3K or 2.5k?