Rookie dodge ram owner here.I will need your experience please. At top gear riding on the highway.I started to notice the rpms goes up about 300-400 rpms and goes back down to normal numbers.

What problem could this be? Trans shifts fine from dead stop to all the gears til i am cruising on the highway about 60-70 mph. Any information would be much appreciated. Thanks.

 

Well is it an automatic or a standard, that helps!

 

Ooops. It's an auto with 90K miles on it now. ATF level is good just recently replaced a few months ago.

 

I had a similar problem, but mine corrilated more with a tach point of 4000 to 4500 rpm. The gear it was in wouldn't slip so to say but pop out because of a fail-safe. It got progressively worse where starting out could be in a 3rd or 4th band rather than a 1st or 2nd. The dealer kept trying to sell me a new trany, the trany shop wanted to change out the cylenoid packs. Finally I decided to try a simple Shift Positioning Sensor (works off of pressure readings) located in the case. while doing this I found that s bolt in the pan was stripped. Between rethreading, replaceing the sensor, flushing the trany, replaceing the filter and rechargeing the fluid I fixed the problem. BUt there should be an error code no matter the problem. Do you know how to retrieve a code via the ignition switch?

 

Could it be the torque converter lockup,kicking in/out???
I know that on my 03, the trans drops by the same amount when she locks the torque converter up at about 55 mph and when the tranny is warmed up.
Are you running on flat ground when this happens?
Is the tranny well warmed up?
Al.

 

via the ignition switch - no i dont. but tomorrow i'll barrow my friend's obdii scanner and scan it. i'll post the codes tomorrow. thanks.

 

yes when its warmed up for sure. and yes mostly on flat roads. just out of no where it would rev up about 300-400 rpms then would go back to normal. i can hear it good since i have the flowmaster exhaust on.

it happens anywhere over 55mph just like you said.

 

It does sound like the converter locking/unlocking, especially at that magic 55mph in top gear???

Get some codes if there are anyand post up.
Al.

 

I'll get it scanned this afternoon. Thanks for the input so far. I really appreciate it.