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Discussion Starter #1
I figured we had the "poor MPG" and "my MPG is great" threads, figured I'd start a bridge/fixed thread.

Here is the original issues at hand for my 2020 Limited, and I believe a lot of you
  1. Overly sensitive throttle, impossible to precisely vary RPMs below 2,400rpm
  2. RPMs too high when cruising in city or hwy, manual shifting would easily lower by 500rpms or more
  3. Poor gas mileage (12-14mpg) in the city, even when using cruise control
  4. Poor gas mileage on the hwy (19-21mpg MAX), even when using cruise control 99% of the time
  5. Erratic and increasing RPMs when going up a hill for no apparent reason, even when reducing throttle
Last week I had the ECU Reprogramming recall performed and immediately I knew we were getting better MPG. After a weeks worth of driving this is what has been corrected (praises respective to complaints):
  1. Very easy to control lower RPMS, engine no longer goes from tons of power at 2,500+rpms to bogging at 1,500rpms - the bogging issue has not occurred once when it used to happen multiple times per day
  2. RPMs when using cruise (or not) in city and hwy are MUCH lower and where they should be - I can cruise through the city around 35-40mpg and the engine will be at 1,200rpms
  3. Gas mileage in the city, using the same habbits and routes, is now 20mpg every day
  4. HWY MPG is not fully vetted, partly due to COVID-19 and limited travel, but I have seen an improvement - just no hard data
  5. RPMs no longer go crazy when going up a typical hill, they stay constant even when letting off the throttle
Now, I have a few myths to bust (yes, not scientific) which some members claimed are the reasons for poor MPG:
  • Ascent is still being warmed up a few minutes prior to leaving for work and prior to coming home.
  • Driving style was not a factor. We continue to drive the Ascent the same as we did before, using a lot of cruise control still in the city and on the hwy. I attribute this to the lower RPMs for acceleration and cruising speed.
  • Temperature is still roughly the same. No crazy delta in the temp, still continue to have a lot of sub-freezing temps.
All in all, my wife and I are VERY happy with the improved MPG. She no longer says "we sold the Yukon to get rid of the 12-14mpg city driving".
 

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2018 Subaru Outback Limited 3.6R, 2003 Honda Pilot EX
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thanks for the info - please do give an update on your highway mileage when you get some data on it.
Also - please continue to monitor this over a few more weeks to give a larger set of data, i.e. more than a few tanks of gas...
Are you filling your gas tank from the same places?
 

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Now, I have a few myths to bust (yes, not scientific) which some members claimed are the reasons for poor MPG...
While those things contribute to overall poor or good gas mileage, they definitely aren't the cause of all of the issues out there. It's the pedal sensitivity which some people get used to easily, and others do not.

You're not the first person to post that the updates have smoothed the pedal response. I've noticed it too - but having a very powerful muscle cars in my past, I was used to "twitchier" pedals. I get whatever gas mileage I want... but getting better gas mileage required smoothing the pedal response by adjusting how I used it.

Having an update that makes that easier is better, of course.
(though I still look for any excuse to use that turbo, lol)

Interesting thing is that a number of people perceive the changes as something that makes the car accelerate slower. It doesn't. I've timed it with and without the update, and am within the margin of error on time differences for acceleration, as tracked by Torque and an Accessport.

But, alas, I think that the original profile made the car seem peppier. Many people did perceive it to be, even though acceleration times are still the same.
 

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Discussion Starter #4
Robert, if the car performed poorly while on cruise control that certain rules out the human factor. I literally could not get my pedal to be very precise, it was very binary.

Human factor aside, driving around town with ACC I was getting 12-14mpg, surges in hills, improper rpms when cruising at a set speed. I'm not sure how you can say this is a "me" issue when it was all car.....and it now performs better being still all car controlled.

If nobody is acknowledging that the mapping, response, ratios of CVT were wrong, then to me that sounds like straight blind denial. I'm now getting sticker MPG with the car in control, previously I could not. Seems very black and white :)
 

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Robert, if the car performed poorly while on cruise control that certain rules out the human factor. I literally could not get my pedal to be very precise, it was very binary.

Human factor aside, driving around town with ACC I was getting 12-14mpg, surges in hills, improper rpms when cruising at a set speed. I'm not sure how you can say this is a "me" issue when it was all car.....and it now performs better being still all car controlled.

If nobody is acknowledging that the mapping, response, ratios of CVT were wrong, then to me that sounds like straight blind denial. I'm now getting sticker MPG with the car in control, previously I could not. Seems very black and white :)
What is your build date? Different Ascents came with different ECU software. Mine was original build.

ACC is sometimes very inefficient, btw. It's a misconception that it's fuel efficient.
 

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Over the past several tanks after the ECU (and TCM and PCV) recalls performed, my mixed driving MPG is now 21+. I was averaging 20.2 prior - not a ton of improvement but I'll take it! I also installed a K&N drop in right at the same time. That may be a factor as well, but can't be certain. I have always been of the belief that hi-flow air filters do not affect MPG. I agree that acceleration is smoother now and the car does "feel" slower, but it will still scoot if I give it more gas.

5 tanks pre-recalls/stock air filter:
20.1, 19.4, 19.5, 18.4, 20.6

5 tanks post-recalls/K&N
23.7 (ski trip), 20.2, 21.7, 21.5, 21.1
(I threw out a 17.8 mpg fill-up that was like 3 gallons. Those small fill-ups are always weird).

Something has changed. I don't think we're on summer blend yet.
 

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Last week I had the ECU Reprogramming recall performed and immediately I knew we were getting better MPG.
I was not aware that there is an ECU flash available for a 2020 model. Does the repair order from your dealer list any details -- like a part number of a program flash or anything like that? What is the build month and year of your Ascent?
 

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In my area the gas blend from winter to summer was recent and my mileage has went up by about 2mpg.
 

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I agree partially: the mpg issue got fixed, but only because with the cheap oil prices we have nowadays, the $$$ in your pocket spent to go from 22mpg to 20mpg are completely negligible. Do the math! And forget the mpg... high/low doesn't matter anymore, just enjoy driving.
 

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Discussion Starter #10
So maybe some of you are missing it, I went from 12-14mpg in the city, to now 19.5-21mpg in the city....the day we picked it up after service, with the same exact driving style/speed/RPMs. And let me be clear, I could never get the thing to do over 14mpg in the city after the first 500 miles of ownership. If you try to blame that on weather, new fuel mix (uhh, its the same tank of gas when I picked it up), a strong tailwind while going downhill everywhere, my engine magically becoming fully broken it when it had service, position of the moon pulling me along like the tide, etc, you are in denial....lol

The Ascent is a 2020MY, built 09/19. The recall done on it says "WUU-06 ECM reprogramming for DTC-C1424". In the Subaru app I had a big recall warning until I got it complete. The service sheet also says "OLD-22765AN500 NEW-22765AN502".

Maybe some of you missed it before so I'll repeat:

Before: When going up a hill the Ascent would increase RPMs for a given speed. If I let off the throttle (or lowered cruise) a little the speed would reduce, but RPMs would continue to sky rocket (beyond 3000rpms)
After: Goes up normal hills like any other car. Keeps steady RPMs, and if I let off throttle to slow the RPMs actually drop

Before: When cruising in town or on hwy the RPMs seemed far too high. This was either with my foot in control or ACC/CC. Putting it into manual would significally drop the RPMs, it always seemed to run in 2 simulated gears too low.
After: Cruising around town or on hwy, my foot or ACC/CC, RPMs are MUCH lower.

Before: If I tried to do a precise low RPM with the throttle I could not. If I was accelerating around 2,200-2,400RPMs and I let off even the tiniest of amounts, the RPMs plummeted and the engine bogged down, as if the turbo got flipped off.
After: I can now move more freely around the lower RPM range and no bogging, even when at the same RPMs where it previously bogged. I understand if you try and say its because they made the throttle less sensitive, but that wasn't the issue. The issue was how erratic it was and at certain RPMs it was just a dog.

Also, cars and electronics are nothing new to me. I have taken auto body and mechanics classes, a slew of electronics courses, 20 years in IT, swapped an engine in a previously owned truck, owned 2 sport bikes that I did all the work on, and if I counted right the Ascent is my 9th vehicle (4th Subaru). I understand that correlation is not causation every single time, but the evidence here is far too strong to be ignored. :)

So yea, if you have a MY2020 with just crap MPG (or any other similar symptoms), get the recall done or ask the service shop to take a look at it.
 

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Our new to use Ascent has pretty normal car behavior but I also see that C1424 was already applied before we got it. You can see the status in the MySubaru mobile app.
 

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The Ascent is a 2020MY, built 09/19. The recall done on it says "WUU-06 ECM reprogramming for DTC-C1424". In the Subaru app I had a big recall warning until I got it complete. The service sheet also says "OLD-22765AN500 NEW-22765AN502".
Great info; thanks!
 

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Now, get a COBB Acess Port for an even better, smoother throttle response that would probably net even better mileage. The Stg 1 87+ map is how this car should’ve come from the factory.
 

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Now, get a COBB Acess Port for an even better, smoother throttle response that would probably net even better mileage. The Stg 1 87+ map is how this car should’ve come from the factory.
I have no experience with anything like this, what is the cost and is it user plug and play or not.

Also, any warranty issues with this type of thing?

Thanks!
 

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So maybe some of you are missing it, I went from 12-14mpg in the city, to now 19.5-21mpg in the city....the day we picked it up after service, with the same exact driving style/speed/RPMs. And let me be clear, I could never get the thing to do over 14mpg in the city after the first 500 miles of ownership. If you try to blame that on weather, new fuel mix (uhh, its the same tank of gas when I picked it up), a strong tailwind while going downhill everywhere, my engine magically becoming fully broken it when it had service, position of the moon pulling me along like the tide, etc, you are in denial....lol

The Ascent is a 2020MY, built 09/19. The recall done on it says "WUU-06 ECM reprogramming for DTC-C1424". In the Subaru app I had a big recall warning until I got it complete. The service sheet also says "OLD-22765AN500 NEW-22765AN502".
Quite a considerable time gap between your ECU and mine. There were a few code changes in between. And yes, remapping the drive by wire gas pedal response affects gas mileage to one extent or another. Either not at all (for those who can work with the previous settings) or greatly, in the exact same cars. That's evidenced by a husband/wife pair in this very forum, where one regulates gas pedal differently than the other. One gets great gas mileage, and the other gets horrible gas mileage. Literally at opposite ends of the spectrum, in the same exact shared Ascent.

I get horrible gas mileage by choice. More so now that I've stuck a roof rack and spare tire on my roof. :ROFLMAO:;):cry:

I'm glad you are finding success with the update. I am hoping everyone does, but, it's such a subjective thing (no two people use the gas pedal the same, and each of us drive different routes in different geographical conditions).

Posts like yours though, give me hope that others will see a benefit.
While the majority of people surveyed in the FB group are showing they're getting +/- 1.5 mpg of EPA ratings, there are people on both extremes, and it would be nice to see more people on the lower end migrate into the EPA rating zone (or higher).
 

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I think too that in the original delivery Ascents (mine Sept 2018) there seemed to be quite a variation in how the CVT operates. Most of the complaints I read about I never experienced. The only one I noticed was the very touchy throttle pedal. I did a test and with only 12% throttle applied found I could out accelerate most econboxes to a 1/4 mile time!

After the recall, the only thing that changed for me is the throttle response smoothed out. I drive race cars, so steering with the throttle is second nature to me so it didn't actually change my mileage at all. YMPGMV :D

It looks like it will help a lot of people though and that is definitely a good thing.
 
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I have no experience with anything like this, what is the cost and is it user plug and play or not.

Also, any warranty issues with this type of thing?
That reflashes the ECU in the car and should void powertrain-related warranty coverage, if I understand it correctly. I think I've read that Subaru can even tell if you've flashed the computer and then put the factory program back on it. Maybe I don't understand the process correctly, but I think that's how it is implemented.
 

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One of my gripes is more CVT related and how the ECU/TCU work in conjunction. In every other (auto transmission) car I've owned, when you go up an incline, the transmission stays in OD gear for as long as possible and then only downshifts when necessary. In the Ascent, if you fart out the window while cruising at speed, it automatically increases RPM (whether its the torque converter "unlocking" or the CVT changing ratios) which put more strain on the transmission. Rule of thumb always has been that you don't want the transmission "hunting" between gears because it accelerates wear, but that seems to be the way this CVT works. I'd much rather have the CVT remain in its "OD gear" and let the engine do the work. I can be cruising on the highway, CC on at 70 MPH and the RPM will jump to 2500 just because I'm going past an interchange with MINOR elevation change. By contrast my EcoBoost F-150 in this same situation would remain in 6th gear and the ECU would add boost (torque) to pull itself up the incline.
If it "is what is is" then so be it...but if there is any way for SOA to fix this or if the COBB tuning fixes this...then sign me up...drives me nuts!
 

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It's a big, beastly chain designed to always be changing ratio, unlike every other design (besides Audi), so, don't worry about it changing ratios - it's not a fragile pushbelt.

Its easier on the engine and transmission when it's properly regulating ratios, meaning when it's not adhering to fixed gears.

?

Try letting Adaptive Cruising Control accelerate from a full stop and see how the CVT should really operate.

One of my gripes is more CVT related and how the ECU/TCU work in conjunction. In every other (auto transmission) car I've owned, when you go up an incline, the transmission stays in OD gear for as long as possible and then only downshifts when necessary. In the Ascent, if you fart out the window while cruising at speed, it automatically increases RPM (whether its the torque converter "unlocking" or the CVT changing ratios) which put more strain on the transmission. Rule of thumb always has been that you don't want the transmission "hunting" between gears because it accelerates wear, but that seems to be the way this CVT works. I'd much rather have the CVT remain in its "OD gear" and let the engine do the work. I can be cruising on the highway, CC on at 70 MPH and the RPM will jump to 2500 just because I'm going past an interchange with MINOR elevation change. By contrast my EcoBoost F-150 in this same situation would remain in 6th gear and the ECU would add boost (torque) to pull itself up the incline.
If it "is what is is" then so be it...but if there is any way for SOA to fix this or if the COBB tuning fixes this...then sign me up...drives me nuts!
 

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So maybe some of you are missing it, I went from 12-14mpg in the city, to now 19.5-21mpg in the city....the day we picked it up after service, with the same exact driving style/speed/RPMs. And let me be clear, I could never get the thing to do over 14mpg in the city after the first 500 miles of ownership. If you try to blame that on weather, new fuel mix (uhh, its the same tank of gas when I picked it up), a strong tailwind while going downhill everywhere, my engine magically becoming fully broken it when it had service, position of the moon pulling me along like the tide, etc, you are in denial....lol

The Ascent is a 2020MY, built 09/19. The recall done on it says "WUU-06 ECM reprogramming for DTC-C1424". In the Subaru app I had a big recall warning until I got it complete. The service sheet also says "OLD-22765AN500 NEW-22765AN502".

Maybe some of you missed it before so I'll repeat:

Before: When going up a hill the Ascent would increase RPMs for a given speed. If I let off the throttle (or lowered cruise) a little the speed would reduce, but RPMs would continue to sky rocket (beyond 3000rpms)
After: Goes up normal hills like any other car. Keeps steady RPMs, and if I let off throttle to slow the RPMs actually drop

Before: When cruising in town or on hwy the RPMs seemed far too high. This was either with my foot in control or ACC/CC. Putting it into manual would significally drop the RPMs, it always seemed to run in 2 simulated gears too low.
After: Cruising around town or on hwy, my foot or ACC/CC, RPMs are MUCH lower.

Before: If I tried to do a precise low RPM with the throttle I could not. If I was accelerating around 2,200-2,400RPMs and I let off even the tiniest of amounts, the RPMs plummeted and the engine bogged down, as if the turbo got flipped off.
After: I can now move more freely around the lower RPM range and no bogging, even when at the same RPMs where it previously bogged. I understand if you try and say its because they made the throttle less sensitive, but that wasn't the issue. The issue was how erratic it was and at certain RPMs it was just a dog.

Also, cars and electronics are nothing new to me. I have taken auto body and mechanics classes, a slew of electronics courses, 20 years in IT, swapped an engine in a previously owned truck, owned 2 sport bikes that I did all the work on, and if I counted right the Ascent is my 9th vehicle (4th Subaru). I understand that correlation is not causation every single time, but the evidence here is far too strong to be ignored. :)

So yea, if you have a MY2020 with just crap MPG (or any other similar symptoms), get the recall done or ask the service shop to take a look at it.
I called my dealer who said the recall was issued in August 2019 and only applies to 2019 models. I have a 2020 built in Dec 2019. The dealer said it should have been taken care of at the factory and they would not do the recall. My CVT seems jumpy at times with sudden downshifts, or getting bogged down with upshifts when accelerating from a stop. The dealer would most likely say it's normal operation?
 
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