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Hi, has anyone had issues with acceleration at speeds under 40? When starting out from a complete stop once the car hits about 20 mph the transmission over-shifts into about 6'th gear. To continue acceleration one needs to heavy down on the accelerator. Instead, if one starts in manual, and shifts up manually there are no acceleration problems. A Subaru head mechanic took a ride with me and told me acceleration complaints with the Ascent are not uncommon and are related to a computer glitch. It was suggested only a manufacturers update to the software can fix the problem. In 30+ years of driving different vehicles I've never experienced weird acceleration issues like this.

Does anyone have experience with a similar issue? Have you been able to get it resolved? When driving in snow and ice the unstable acceleration is quite frustrating and probably dangerous.
 

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Hi, has anyone had issues with acceleration at speeds under 40? When starting out from a complete stop once the car hits about 20 mph the transmission over-shifts into about 6'th gear. To continue acceleration one needs to heavy down on the accelerator. Instead, if one starts in manual, and shifts up manually there are no acceleration problems. A Subaru head mechanic took a ride with me and told me acceleration complaints with the Ascent are not uncommon and are related to a computer glitch. It was suggested only a manufacturers update to the software can fix the problem. In 30+ years of driving different vehicles I've never experienced weird acceleration issues like this.

Does anyone have experience with a similar issue? Have you been able to get it resolved? When driving in snow and ice the unstable acceleration is quite frustrating and probably dangerous.
Yes, it's pretty common. This is probably the most recent thread on this but there are more. Supposedly a re-flash will be available at some point in the neat future. I almost think mine has gotten smoother over time, but it's still there.

 

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Discussion Starter · #3 ·
Yes, it's pretty common. This is probably the most recent thread on this but there are more. Supposedly a re-flash will be available at some point in the neat future. I almost think mine has gotten smoother over time, but it's still there.

Thank you for directing me to the other discussion thread. I'm new to the forum and didn't see the discussion after a simple search. I'll keep my eyes open for the "reflash" and print out the advice on changing spark plugs for the dealer to consider mentioned in the other thread.
 

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I posted in the "My Letter To Subaru" forum...literally my letter to Subaru about this. Motor Trend even commented about this in their long term review update of their Outback XT. It's probably easy to pay less attention to a bunch of internet know-it-alls, but when a globally-respected magazine writes an article and feels strongly enough about the driveability concern to mention it to their readers...it's probably a legit complaint.

So -- write a letter to Subaru on it. They'll tell you they'll file it with their engineering department...and the more reports they have from customers, the more likely they are to want to address it.
 

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Hi, has anyone had issues with acceleration at speeds under 40? When starting out from a complete stop once the car hits about 20 mph the transmission over-shifts into about 6'th gear. To continue acceleration one needs to heavy down on the accelerator. Instead, if one starts in manual, and shifts up manually there are no acceleration problems. A Subaru head mechanic took a ride with me and told me acceleration complaints with the Ascent are not uncommon and are related to a computer glitch. It was suggested only a manufacturers update to the software can fix the problem. In 30+ years of driving different vehicles I've never experienced weird acceleration issues like this.

Does anyone have experience with a similar issue? Have you been able to get it resolved? When driving in snow and ice the unstable acceleration is quite frustrating and probably dangerous.
A CVT does not have 'shift points' as it's number one job is to keep the Trans at a pre- fixed number.
 

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A CVT does not have 'shift points' as it's number one job is to keep the Trans at a pre- fixed number.
For pure CVT operation that's true. Unfortunately, Subaru's programming for the CVT in our Ascent does have "fake shift points" that come into play and can be felt. It's one the most mentioned annoyances from owners here in the forums.
 

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In addition to my 2020 Ascent. I have a 2019 Outback 3.6R. The 6 cylinder engine mated with the CVT in the Outback has a very smooth power delivery, a real pleasure to drive. To bad Subaru did away with that 6 cylinder.
 

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In addition to my 2020 Ascent. I have a 2019 Outback 3.6R. The 6 cylinder engine mated with the CVT in the Outback has a very smooth power delivery, a real pleasure to drive. To bad Subaru did away with that 6 cylinder.
Alas, the H6 3.6R is not powerful enough for the Ascent, has a worse torque curve and eats more gas. The CVT in both is a TR690. Programming differences are the likely culprit for the differences in shifting, as well as turbo spooling sometimes.
 

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Alas, the H6 3.6R is not powerful enough for the Ascent, has a worse torque curve and eats more gas. The CVT in both is a TR690. Programming differences are the likely culprit for the differences in shifting, as well as turbo spooling sometimes.
True, but why not consider a turbo on the H6. I think the drivability, power delivery, and fuel consumption would have been better with 6 cylinders. The fun comes from the turbo.
 

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True, but why not consider a turbo on the H6. I think the drivability, power delivery, and fuel consumption would have been better with 6 cylinders. The fun comes from the turbo.
I imagine it'd have been pretty hard for Subaru to hit their fuel economy targets with a turbocharged 6-cylinder...and it'd likely have blown right through, pardon the pun, their power and torque targets. They've made the Ascent quite competitive with its peers in the power department -- the FA24F offers plenty of it, and at much more usable speeds than most competitors' V-6 engines. And, at the same time, Subaru achieved fuel economy numbers that are near the top of the class for 7/8-passenger SUVs. To have near best-in-class fuel economy and excellent power and torque at the same time is quite laudable to me (all while using 87 octane).
 

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True, but why not consider a turbo on the H6. I think the drivability, power delivery, and fuel consumption would have been better with 6 cylinders. The fun comes from the turbo.
Because it already has horrible gas mileage. The H6 doesn't remotely compare to what the FA24F DIT engine can do. It's a horrible choice. Here's the naturally aspirated H6 in the slightly lighter Tribeca:

Premium Gasoline Only
  • 16 city
  • 18 combined city/highway
  • 21 highway

With a turbo on that, it'll get a lot worse. It'd be fast as heck, and a beast off-road..... but, oh the cost of going a few miles. :cautious:
 

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In addition to my 2020 Ascent. I have a 2019 Outback 3.6R. The 6 cylinder engine mated with the CVT in the Outback has a very smooth power delivery, a real pleasure to drive. To bad Subaru did away with that 6 cylinder.
I traded in my Outback for the Ascent. But one thing on that very smooth power delivery is 256 vs 266hp also 700 hundred more pounds to divide 10 to 12 ponies.
 

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Because it already has horrible gas mileage. The H6 doesn't remotely compare to what the FA24F DIT engine can do. It's a horrible choice. Here's the naturally aspirated H6 in the slightly lighter Tribeca:

Premium Gasoline Only
  • 16 city
  • 18 combined city/highway
  • 21 highway

With a turbo on that, it'll get a lot worse. It'd be fast as heck, and a beast off-road..... but, oh the cost of going a few miles. :cautious:
Hi Robert

Only the B9 Tribeca (2006-2007) required premium fuel and it used the EZ30D. At the time, I believe it was one of the highest horsepower engines in the 3.0 class. (250hp*) *It was listed at 250 at the time of release, but Subaru had to republish the rated power because Subaru calculated the HP rating differently. But, it was not a good choice for an SUV as it was low on torque. In 2008-, Subaru switched to the EZ36, same fuel mileage, and it only required regular (87 octane). This engine had more torque, but both the H6s are an old engine design so the fuel economy would still be terrible.

This is just my internet rambling, but what if Subaru took the more modern FB2.5 and added 2 more cylinders and made a hypothetical FB3.8 H6. Doing some napkin mathematics, this hypnotical 3.75liter H6 could make 270ish HP and 260ish lb-ft of torque. That is certainly close to the FA24F DIT. Just a thought...
 

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Right, but at the cost of a bunch more gas. 😉

No Subaru H6 was fuel efficient in comparison. Anyway, I used the Tribeca because of the weight. Look at the gas mileage rating difference between the 2020+ Outback XT and the Ascent.
 

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This is just my internet rambling, but what if Subaru took the more modern FB2.5 and added 2 more cylinders and made a hypothetical FB3.8 H6. Doing some napkin mathematics, this hypnotical 3.75liter H6 could make 270ish HP and 260ish lb-ft of torque. That is certainly close to the FA24F DIT. Just a thought...
In addition to the peak torque number, where that peak torque occurs is a pretty impactful metric for engines in large vehicles. The FB series engines produce peak power at between 5,800 and 6,000 rpm depending on the variant (FB20, FB25, etc.) and peak torque occurs at between 4,000 and 4,400 rpm (the direct injected FB engines actually have the highest peak torque engine speed, at 4,400 rpm).

The really nice thing about our FA24F engines is peak torque occurs at 2,000 rpm (with a lot of it available even sooner than that). And, because of the unique ability of a turbocharged engine to keep a super flat torque curve, we keep that peak torque all the way through 4,800 rpm. That's a really outstanding package for a large SUV intended to tow up to 5,000 pounds.

A 6 cylinder has other challenges related to packaging. Our FA24s are fairly tight in the engine bay. There's some extra room, but not a lot. A 6 would either mean a much tighter engine bay with more difficult servicing of simple things...or...our long nose would become even longer. A 6 would also be heavier than the turbo 4. Of course, none of this is insurmountable. But Subaru apparently think the gains are worth the costs.
 

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A 6 cylinder has other challenges related to packaging. Our FA24s are fairly tight in the engine bay. There's some extra room, but not a lot. A 6 would either mean a much tighter engine bay with more difficult servicing of simple things...or...our long nose would become even longer. A 6 would also be heavier than the turbo 4. Of course, none of this is insurmountable. But Subaru apparently think the gains are worth the costs.
Oops, what I clearly meant, but totally mistyped, is "Subaru apparently don't think the gains are worth the costs"...or we'd have an H6-powered Ascent. :)
 

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Oops, what I clearly meant, but totally mistyped, is "Subaru apparently don't think the gains are worth the costs"...or we'd have an H6-powered Ascent. :)
True, but I also believe Subaru would not be able to sell an H6 in another market as most countries tax by engine size. It would be too expensive to develop an engine just for North American market.

Subaru H6 engines are not much longer than the H4s. Being an old Subaru fan, I remember a case where the H4's were actually longer than the H6s. I speak of the mythical twin turbo'ed EJ20 that was only available Legacy. It was never offered here due to the twin turbo setup, the engine would not fit left hand drive cars.

Right, but at the cost of a bunch more gas. 😉

No Subaru H6 was fuel efficient in comparison. Anyway, I used the Tribeca because of the weight. Look at the gas mileage rating difference between the 2020+ Outback XT and the Ascent.
True, but the EZ family of engines are ancient. A modern H6 engine would no doubt consume less fuel. I looked up the fuel economy of my 1st Subaru, a 1998 Legacy 2.5GT and the fuel economy was 18city/24hwy vs a 2020 Legacy with the FB25 ( 27city/35hwy). What an improvement from the old EJ25 engine to more recent the FB25.

A more interesting comparison is the 2008 Legacy 2.5GT (H4Turbo) vs the 2008 Legacy 3.0R (H6). Same car, same transmission, same fuel requirements. The GT's fuel economy was 18/24 while the 3.0R was 17/24 with the GT having a slight advantage in city mileage. That is why I think if a modern H6 existed, it would be comparable to FA24DIT.
 

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Except for the worse power delivery. 😉
 

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Keep in mind the EPA had somewhat significant changes in 2008, and more modest changes in ~2017 that make an apples to apples comparison of fuel economy values difficult over that period.

The net effect of the changes meant the economy ratings were lowered, so a my2005 vehicle would perform (significantly) worse under the current standards.

Slightly offsetting that is not only are vehicles more efficient in general now than 15+ yrs ago, but also manufacturers are more adept than ever at gaming the system to improve their performance in the EPA tests.

But the real variation in mpg occurs with temperature, driving conditions, geography, and the weight of your right foot.

And yes, I do experience that ' sag' in power delivery at low speeds, I blame the engine/cvt calibration, as the engine itself has plenty of power otherwise.
 
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