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Has anyone had this same issue with accelerating at 40 mph?

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My husband I just purchased our 2007 Acadia with 14,000 miles, we now have around 18,000 and we have noticed an accelartion problem at 40 mph. When you slow down to 40 mph and try to accelerate it is as if there is no gas going to the engine, eventually you do accelerate but it is as if you are taking off in a spaceship. Has anyone else experience this problem?
 

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myoung said:
My husband I just purchased our 2007 Acadia with 14,000 miles, we now have around 18,000 and we have noticed an accelartion problem at 40 mph. When you slow down to 40 mph and try to accelerate it is as if there is no gas going to the engine, eventually you do accelerate but it is as if you are taking off in a spaceship. Has anyone else experience this problem?
Bring it to your dealership and make sure it has had all of the transmission updates done. The May '08 one was optional, but you might want to have that done as well if it hasn't been. Use the search feature on the forum to look up the threads on the transmission and acceleration issues, you're sure to find some that match what you're experiencing.
 

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Welcome to the forum.

The main acceleration issue is you have a relatively heavy vehicle with a relatively small motor.

GM, like other manufacturers, is subject to excessive governmental regulations for fuel economy, smog, and safety standards. A direct result of this is they program vehicles to get into as high a gear as soon as possible so as to minimize emissions and maximize MPG.

As Queen Web mentioned, there is an update available that will reflash the transmission to improve the shift points. Your dealer will be able to tell if this has been done yet.
 

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Low mileage; so it shouldn't be a trans slipping issue although stranger things have happened
 

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Blue_2009_SLT2 said:
Welcome to the forum.

The main acceleration issue is you have a relatively heavy vehicle with a relatively small motor.

GM, like other manufacturers, is subject to excessive governmental regulations for fuel economy, smog, and safety standards. A direct result of this is they program vehicles to get into as high a gear as soon as possible so as to minimize emissions and maximize MPG.

As Queen Web mentioned, there is an update available that will reflash the transmission to improve the shift points. Your dealer will be able to tell if this has been done yet.
Blue, I get real tired of your "heavy vehicle with a ... small motor" flap! Two hundred and seventy-five horsepower is more than enough to get the Acadia moving out smartly and cruising efficiently! No, it's not a top-fuel dragster - but I drove armored vehicles at least three times heavier with much less horsepower that really got out of the way when they needed to do so! That excuse you constantly throw at people is really quite lame, DUDE!

The Gov't stuff about dictating the programming to control how we need to drive is the prime culprit. The Acadia would perform much better if they gave up on the fly-by-wire crap and went back to positive response systems using cables and linkages. That would allow for less buggy ECM programming, better performance and a lot greater fuel efficiency. All the politicos and computer nerds keep us thinking we're really making progress when all we're doing is sliding backwards through the muck.

Take that to your GURU hut and dwell on it for a while.
 

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speleos said:
Blue, I get real tired of your "heavy vehicle with a ... small motor" flap! Two hundred and seventy-five horsepower is more than enough to get the Acadia moving out smartly and cruising efficiently! No, it's not a top-fuel dragster - but I drove armored vehicles at least three times heavier with much less horsepower that really got out of the way when they needed to do so! That excuse you constantly throw at people is really quite lame, DUDE!

The Gov't stuff about dictating the programming to control how we need to drive is the prime culprit. The Acadia would perform much better if they gave up on the fly-by-wire crap and went back to positive response systems using cables and linkages. That would allow for less buggy ECM programming, better performance and a lot greater fuel efficiency. All the politicos and computer nerds keep us thinking we're really making progress when all we're doing is sliding backwards through the muck.

Take that to your GURU hut and dwell on it for a while.
Well whatever the reason the Acadia is somewhat gutless. It would be so much better if it could shed about 500 pounds.
 

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speleos ,
I won't reply in kind seeing as how you appear to be agreeing with me as to the cause. Instead, after visiting a few Guru huts will offer up the following similar to the Envoy vs. Acadia comparison I did:

A smaller engine can make a whole bunch of HP- as I've also observed here, the 3.6L DI motor makes more HP than my 5.7L 1995 Trans Am did stock. The DI motor is rated at 288 HP @6300 RPM and 270 ft-pounds of torque @3400 RPM.
GM 2009 Acadia specs

Torque is what moves a vehicle. HP is torque over time. A smaller displacement engine will not make as much torque as a larger one. What is the redline on the Lambda motor- 6500~7,000 RPM? Our tach is not marked for this and I couldn't find this info anywhere. It makes the 288 HP well up into the RPM range. How much time does the average driver spend there or even close to there? This makes the higher HP far less relevant to a daily driver, unless perhaps your commute includes Road Atlanta or VIR :). Coupled with the six speed automatic, you're going to see more shifting to get anywhere close to best acceleration.

I also drive a heavier vehicle with less HP. It's called a 10 year old Durango that when new was rated at 245 HP. Even with like 140K on the clock, it has decent acceleration as compared to the Acadia even with less HP and larger (wider) tires. Why? The 5.9L V8, the four speed automatic trans, and the final drive ratio. The 245 HP is rated at 4000 RPM, while it makes 335 torque at 3200 RPM (statistically, this is 24% more than the Acadia). My truck also has a 3.92 final drive ratio, compared to the 3.16 of the Acadia. If the same vehicles have a 3.16 and 3.92 final drive ratios, the 3.92 will accelerate faster than the 3.16 equipped vehicle. My truck also averages 11-12 MPG vs. 19-20 for the Acadia.
Durango specification from Allpar

For a more drastic comparison, I've also noticed this "seat of the pants" when comparing my new 376 HP @5150 / 410 TQ @4300 5.7L Challenger to the modified 550~600 HP 6.2L Trans Am (prior to the last turbo upgrade, it dynoed 498 @4700 and 579 @4300 at the wheels- figuring a very conservative 5% powertrain loss, this is 522 HP / 607TQ at the motor to directly compare with the other ratings). The Challenger is probably about 800 pounds heavier, and even though it has a better final drive (3.93 vs. 3.73), the Trans Am will out accelerate it and outrun it due to the far higher torque, lighter weight, and taller gearing.

Back to the topic, the thread starter is worse off since he has a less powerful 2007 model, since the DI was not offered until 2009.

The fact is, the average driver/customer has no idea about technical stuff like this nor do they care. They want to get in, turn the key, and go without any issues. As a former service writer, I'm not telling you anything you don't know in this respect. After they buy, one owner you will never see and another will be in for every problem, real or perceived.

What I've referenced are facts, not an excuse. These facts form the basis for my responses here. There's no need to use an insulting manner towards other members.

We're quite happy with the way our 2009 Acadia drives. It won't pass other vehicles on the two lane like my other vehicles, but that's a given based on the above.
 

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i being the owner of a 2007 (with tranny updates),will agree that it needs the tranny upgrates. This will give ya alittle better gearing in the 'dead' areas.

want to read bout it...do a search on transmission updates/upgrades.......

as for as power....imo, for what it is it does a good job. If U run the gears this is a peppy 6cyl.....combined with handling it's a great cuv......no hot rod though.
 

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This is why there is more bang for your buck with electric motor assist hybrid systems in large vehicles. Torque from an electric motor is available at all RPMs.
 

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I had the exact issue and spoke with a transmission engineer at GM. He stated that the early transmission software had a bug that allowed the transmission to try and engage 4th and 5th gear at the same time under certain conditions like you discribe. This does not cause any harm but is not right. The transmission flash discussed above cured my problem.
 

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I don't have a hesitaion but I know there is a gear change in there. I did have a flash done to the tranny.
 

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shot_1 said:
i being the owner of a 2007 (with tranny updates),will agree that it needs the tranny upgrates. This will give ya alittle better gearing in the 'dead' areas.

want to read bout it...do a search on transmission updates/upgrades.......

as for as power....imo, for what it is it does a good job. If U run the gears this is a peppy 6cyl.....combined with handling it's a great cuv......no hot rod though.
As an owner of a very early '07, I agree with Shot 1 completely :cheers:
 

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We have NO PROBLEM w acceleration w this tank w V6 w 275HP including 2 tranny software updates. Great mpg too! Want more oommph, buy a V8 SUV and get 12mpg! Some people have to adjust to limitations with what they purchase and move on. Homework first before you buy!
 

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teetertotter said:
Homework first before you buy!
In the Original Poster's defense, they bought it used and it's quite possible that it hasn't had the tranny flashes - which is why I recommended they check with the dealer. :) I recall early on experiencing some funky hesitation around the 40-45mph mark and the trans updates took care of that.
 

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Web Raven said:
In the Original Poster's defense, they bought it used and it's quite possible that it hasn't had the tranny flashes - which is why I recommended they check with the dealer. :) I recall early on experiencing some funky hesitation around the 40-45mph mark and the trans updates took care of that.
Methinks you're right, Oh Queen! The programmers tried a bit too hard to make the Acadia feel like it wasn't shifting much like vehicles equipped with CVTs. It just didn't work out as well as they thought it would. They got it pretty good the third time around. I just hope the nerds don't try to force us into a 10- or 12-speed transmission the next time they have a 'bright' idea.
 
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