Shift Pattern ?

[Rado]

2015 1500 Pentastar V6 8 Speed transmission ! All seems fine BUT it does seem to take it time shifting to 8th. Seems when it drops down, whether hill or acceleration, Stay around 2k RPM,longer then I think it should ! Avg cruise about 1500/1700 RPM Has there been any TSB on this transmission ? My MPG IMO is good 20/21 combo and highway maybe 22 mpg . Am I over thinking this ? Thanks

 

[huntergreen]

2015 1500 Pentastar V6 8 Speed transmission ! All seems fine BUT it does seem to take it time shifting to 8th. Seems when it drops down, whether hill or acceleration, Stay around 2k RPM,longer then I think it should ! Avg cruise about 1500/1700 RPM Has there been any TSB on this transmission ? My MPG IMO is good 20/21 combo and highway maybe 22 mpg . Am I over thinking this ? Thanks

Would this shifting behavior be influenced by the gear ratio ?

I would expect a bit better hwy mpg. My hemi will see 21. Mpg on the highway with my hemi if I stay at 70 mph.

 

[Rado]

Would this shifting behavior be influenced by the gear ratio ?

I would expect a bit better hwy mpg. My hemi will see 21. Mpg on the highway with my hemi if I stay at 70 mph.

I have 3:21 gears.Stock size tires No lift.. So far my best MPG at 75 mph has been 23.4 but avg 21/22 . IMO not too bad And from what I have read the Hemi like yours runs the same or close! Just curious about the RPM and shifting on mine! AT best if it did need a transmission flash I might gain 1 or 2 mpg. But that transmission seems to take its time shifting too 7 and 8th. I have heard the flash was on the Hemi but not sure what gears or transmission it was for. I think 2014 and below!

 

[Quyonmob]

Takes forever to hold 8th with 3.21s and my pentastar. The should have never spec’d It that way, 3.55 should have been minimum.

That said, your hwy mpg isn’t great, I see around 24mpg but at 70mph.

 

[Rado]

Takes forever to hold 8th with 3.21s and my pentastar. The should have never spec’d It that way, 3.55 should have been minimum.

That said, your hwy mpg isn’t great, I see around 24mpg but at 70mph.

I was figuring a little more MPG with the 3:21/ But so far the best I ever got was 23.4 if memory is right lol I would love to see 24 MPG all the time Will see what I get with my new tires and summer gas . We are still on winter blend . My next trip I will cruise at 70 mph and see if that makes any difference !

 

[tnctx02]

Mine doesn't stay in 8th most of the time on the highway. I am averaging 19mpg after my lift and 35" tires. Could it be the trans or maybe the 3.21 rear end causing this?

 

[Tim Garceau]

Even the 5.7 struggles to hold 8th with 3.21 gears stock, FCA was looking for class leading mpg with this combo.

 

[Burla]

Even the 5.7 struggles to hold 8th with 3.21 gears stock, FCA was looking for class leading mpg with this combo.

thats a bad blue truck, sorry can't help the OP, but had to mention I like that thing.

 

[Rado]

Thanks everyone for your info. I wonder if a re flash of the transmission would help ? Now we are starting to get summer gas again I am averaging 21 mpg around town. But I am sure I will still see a Hwy Avg of 22 mpg+ at 75 mph. My next trip I will try and keep it at 70 mph max and see what happens

 

[huntergreen]

Thanks everyone for your info. I wonder if a re flash of the transmission would help ? Now we are starting to get summer gas again I am averaging 21 mpg around town. But I am sure I will still see a Hwy Avg of 22 mpg+ at 75 mph. My next trip I will try and keep it at 70 mph max and see what happens

A lot of variables come into play. I'm your case, on a hwy trip, if most flat terrain, I would think you should see 25 mpg.

 

[Troy Gillis]

Even the 5.7 struggles to hold 8th with 3.21 gears stock, FCA was looking for class leading mpg with this combo.

Struggles? Im in eco in 8th for hours on my drives with that setup..

 

[ThunderMug95]

I just look at it like this, its basically a 6speed with a double Overdrive transmission. Both 7/8 are sub 1:1. I just accept that it is going to shift in and out quite frequently. As for ECO, religiously set it to 8 to keep the annoying MDS in hibernation. Sometimes if I know Im not going a route that is at least 55mph, I just select 7.
The best thing for mpg is being smooth and picking your lines anyways. See the lane change 1/4 mi away and not get pinned in so you have to brake and then accelerate. Just my 2 cents.

 

[Tim Garceau]

Struggles? Im in eco in 8th for hours on my drives with that setup..

What speeds, my FILs used to hunt gears and was apparent due to muffler swap from 60-70mph with wind or any incline.

ECO just means you’re in an efficient mpg state, does not necessarily equate to 8th gear or MDS active.

 

[Troy Gillis]

What speeds, my FILs used to hunt gears and was apparent due to muffler swap from 60-70mph with wind or any incline.

ECO just means you’re in an efficient mpg state, does not necessarily equate to 8th gear or MDS active.

I travel in the 65-75mph range, and know Im in 8th as I was taught to downshift for slowing down over braking.. When I tap the down shift, it comes up in 8th gear on the dash.

 

[Rado]

I travel in the 65-75mph range, and know Im in 8th as I was taught to downshift for slowing down over braking.. When I tap the down shift, it comes up in 8th gear on the dash.

I just let off the gas when coming to a light but will try the down shift button and see what I find Thanks for the idea

 

[Rado]

A lot of variables come into play. I'm your case, on a hwy trip, if most flat terrain, I would think you should see 25 mpg.

Good info but the only thing flat up here in Maine is my head :O Not big hill but not flat like Fla. lol

 

[CVX20]

The motor doesn't have enough balls with that ratio to keep it in the big gear.If it did go into 8th you'd be lugging the motor and get worse mileage.The beauty of the 8 speeds is that it keeps it in the right gear with the power available to get the best mileage.