Rpm fluctuating

[tyler.r.jacobs]

2015 silverado 1500 4x4 LT 5.3

 

Since day one I drove it off the lot the rpms have been fluctuating 100-400 crusing at 45-55 steady. Dealership says it's from my lift and tires but I told them it has been this way since day one. I'm thinking it has something to do with a servo possibly in the trans or maybe an issue with overdrive. Any help or info is appreciated. Truck is lifted 9" on 35s

[LongrangeLauber]

Put it in manual mode and keep it in 5th gear and also try 4th. If it doesn't do it, something is slipping in the overdrive gear

[tyler.r.jacobs]

Put it in manual mode and keep it in 5th gear and also try 4th. If it doesn't do it, something is slipping in the overdrive gear

Ok so I need to just switch it in manual mode once I get to that speed and see what happens at M4 and M5. I'm assuming it's gonna cause it to not go into overdrive.

[LongrangeLauber]

Ok so I need to just switch it in manual mode once I get to that speed and see what happens at M4 and M5. I'm assuming it's gonna cause it to not go into overdrive.

Yes. Whatever gear is selected in manual mode is the highest gear the truck allows. That being said manual mode isn't exactly entirely manual. But that's a conversation for another day and another thread lol

 

Just get rolling down the highway then shift into manual mode. It will automatically kick into 4th gear. You can run 4th another see if it does it still, but you should be fine with just 5th gear

[BigBadSierra]

I only have issue with mine when it's close to needing an oil change. I can tell just by how it's running that it's ready. Of course all the GM products I've ever owned seemed to be the same way.

[gone_fishing]

Do you experience this fluctuating when driving at a steady speed (cruise control) or when lightly accelerating? If it's during acceleration it could be the torque converter locking up.

[tyler.r.jacobs]

Appreciate the responses and I see it only when holding a certain speed. The truck real sluggish at start sometimes and acts like it wants to shut off

[redwngr]

5th and 6th are both overdrive ratios.

There is no 1:1 in the 6L80

R 1 2 3 4 5 6

6L80 MYC 3.060 4.030 2.360 1.530 1.150 0.850 0.670