Lift and sifting issues

[Buckeye2019]

2015 express 5.7 8speed trany 2 wheels drive. So after putting on the lift 7inch max tracks also 20x12.5 toyo tires. When I'm on the highway if it's flat it's ok othe then that it's shifting back in forth from 8 to 7th gear. So do I need a different gear set up? Would a tunner take care of the problem?

 

[Jershipe]

Did you get the speedometer recalibrated for the tire size? Makes a big difference in the shifting.


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[H3MI UP]

Did you get the speedometer recalibrated for the tire size? Makes a big difference in the shifting.


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This is a must

 

[Buckeye2019]

No I didn't. How and where would I get this done at?

 

[Jershipe]

I bought a used diablosport tuner. Was about 200$. Think you can buy just speedometer recalibration programmer. But I wanted to tune mine and turn off the mds anyway. So that was the best bang for my buck.


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[H3MI UP]

No I didn't. How and where would I get this done at?

I had the dealership do mine and it's perfect

 

[Buckeye2019]

I will have to ask my dealer if he can do that on my next oil change.

 

[Buckeye2019]

Can someone tell me what the dealer can do cause I called mine today and he said they can't flash the computer for bigger tires sizes.

 

[Jershipe]

Think it depends on the dealer. Seems like some dealers will and some of them suck.


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[H3MI UP]

Think it depends on the dealer. Seems like some dealers will and some of them suck.


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Exactly

 

[Buckeye2019]

Hpstang thanks I called my dealer and explained to them and now I have appointment nexted weekend.

 

[Ferro]

I had the dealer do mine.

 

[Buckeye2019]

Gerri was there a difference in the sifting of the truck?

 

[DannyMK2]

how tall are your tires and what gears do you have?

 

[Schmittj22]

2015 express 5.7 8speed trany 2 wheels drive. So after putting on the lift 7inch max tracks also 20x12.5 toyo tires. When I'm on the highway if it's flat it's ok othe then that it's shifting back in forth from 8 to 7th gear. So do I need a different gear set up? Would a tunner take care of the problem?

Buckeye, I had the same issue. I am running 4 inch lift, bilsteins at 2.1, and 35s. Your higher and wider so I am sure you are having issues.

Only way to recalibrate on a 2015-2016 is too get a diablo tuner. But with this you will need a DCX PCM or send your pcm in ($1200 new). I was lucking to have bought mine used for $650.

I just got a hemifever 91 oct tune and its amazing. averaging 17.1 mpg and acceleration and shifting is much improved.

 

[Buckeye2019]

I have 35 12.5 on a 20 inch fuel. I did call the dealer and they said they can go in and flash the ECM to accommodate for the bigger tires

 

[Buckeye2019]

Well y'all I went and got my free oil change for life today and they flashed the computer for me for free. So I just wanted to say thanks for everyone who let me know about this. The truck is like it was before I installed the lift. No more issues with shifting and it even drove great in ecomode.