Ok, I've got a 1500 2wd 4.7L auto trans. I changed the fluid and filters last summer, and the fluid in it did not look bad. Truck had 160K miles at the time. Lately, the truck has an odd rpm fluctuation on the highway. Sometimes when I hit a bump with both rear wheels at once, the rpm's bump up about 200 rpm. Other times it's when you go up a grade, and the same thing occurs. This is usually on the first trip of the day, but not always. It's awful when the cruise is on, I don't even use it. This leads me to believe it is an electronic issue, not a true slip. The range of rpm's in question is like 1800- 2000 rpm. The same thing happens when I keep the truck out of overdrive, so that's not it either. Any suggestions?

 

Sounds like your torque converter.

 

i know this is bringing back the dead thread.

i picked up a used 08 4.7 1500 60k miles. bout a week after i bought and started to really feel the truck out i noticed what seems to feel like a little rpm slip... with o/d on or off doesent matter. with o/d off it just happens a lil higher in the power band.. eother way when i accel up to around 2000 the rpms will climb then they will kinda just stop or even slightly dip.. truck still gaining speed all the time... when od is on it does it around 3000 and u can see the rpms needle flucuatiing right around the 3 untill it pushes passed it. the car fax did have something at 30k with the torque converter rebuild... i dunno. its not major but it does make me a lil upset.

 

sounds like a TC to me too.... but sometimes if the Trans filters aren't installed right after a fluid change they can cause problems....

 

It's worth puttting in a TPS- a throttle position sensor. An import part will cost around $50- and it fixed my problem immediately. Would have bet you my truck title it was a slipping tranny too. But it was the TPS.

 

does the 2008 have the tps by the throttle body?