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Well today I was driving the Acadia home from work.. and been watching the DIC average mpg.. and noticed that it was a bit lower than what it had been in the past. Thought maybe I'd gotten some crappy gas or something. The other day I'd reset it on the way home and managed 27.7mpg.. so I figured I'd do the same today to see what I could get. I was lucky to get over 20-22mpg on the same stretch of road.. same easy throttle ect... I normally notice that when cruising at 55mph on cruise the tach reads about 1300-1500rpm. Today.. I noticed that it was about 2000rpm w/ the cruise on DIC reset registering 20-22mpg... I speculated that the transmission wasn't shifting to 6th gear. I shifted to low.. and tried shifting it manually.. shifted from 5th to 6th.. and noticed no change in RPM. Then later had it in D and was cruising at 55mp w/ the cruise on.. and again registered 1300-1500rpm.. and reset DIC and registered 25-27mpg.

Shouldn't the tranny shift to 6th when I have it in low manually.. and shifting from 5th to 6th should result in a drop in RPMs.. Just a lil confused????

Has anyone else noticed anything like this in their Acadias? I know the DIC isn't exactly the best way to gauge fuel mpg... but just something interesting that I noticed.. and thought that I'd throw out there.

I will continue to monitor.. and see if I observe the same results.. and if so.. will bring them to the attention of the dealer.
 

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If you are at a speed and/or on a grade that the tranny would automatically select 5th gear, then shifting with the 'L' option from 5-6 would not make a change. The 'L' option picks the highest gear that the tranny will shift up to, but the tranny still is an automatic and will shift down when it thinks appropriate.
 

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One reason I like my magnaflows is that when my car goes over 2000 rpm's, I hear it.
 

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Could be a strong head wind.
 

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6th gear torque convertor lock-up is what you are most likely seeing.
 

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badtranny said:
I actually get better mileage if i leave mine in 5th gear! & it stops all that goofy gear changing
Sounds like you really need that most recent transmission software update. Maybe try dealer number 3?
 
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