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Hi everyone, new to the forum, and a new Subaru owner. Just picked up a 2018 Impreza Sport in manual last Monday. I've really been enjoying it so far and I have about ~700 miles on it. I know I'm still in the break in period but I've been having a kind of wierd issue, I don't know if I should take it back to the dealership or something, this is also my first brand new car. It seems like in second and third gear specifically, but sometime fourth, I'll get what kind of feels like the engine lugging, but all the way up to 4000 rpm. It's hard to explain it but I would say its similar to accelerating on a motorcycle that has a dirty carburetor. It accelerates, then almost like, skips for a second? It just makes for an overall un-smooth acceleration and I'm wondering if maybe I have something wrong? Should I bring it back, or maybe just try higher octane fuel?

Thanks in advance for any help you can provide.
 

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Welcome!

I was told when I bought the car that the ECU has to go through a "learning" period. The car has to learn many things and learn your driving style as well. I know this sounds strange. My dealer told me to do "jack rabbit" starts as much as I could (but not to redline it) for the first month of ownership.
 

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Discussion Starter #3
Welcome!

I was told when I bought the car that the ECU has to go through a "leaning" period. The car has to learn many things and learn your driving style as well. I know this sounds strange. My dealer told me to do "jack rabbit" starts as much as I could (but not to redline it) for the first month of ownership.
Yeah I guess I can see that, I had assumed that since I was within the break in period it could just be that. I do notice that it only feels not smooth when I'm accelerating lightly, if I floor it the power comes on smooth.
 

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I have a CVT and during my break in period I experienced some "stuttering" at low speeds around 1000-1500rpm. Similar to CJ I was also told this was normal and part of the "learning" process. I just broke 6,000 miles and that issue isn't an issue anymore. I can't speak for manual, but I'm sure it will dissipate as you drive it more.

Thanks for joining the forum!
 

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I have a CVT and during my break in period I experienced some "stuttering" at low speeds around 1000-1500rpm. Similar to CJ I was also told this was normal and part of the "learning" process. I just broke 6,000 miles and that issue isn't an issue anymore. I can't speak for manual, but I'm sure it will dissipate as you drive it more.

Thanks for joining the forum!
Thanks, I appreciate the response! I guess I'll just keep driving for a while and see how she goes. I think I still may just be readjusting to driving a car with a manual transmission, although I'm sure all this Boston traffic will strengthen my left leg quickly! :laugh:
 

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There are a few of us....all with manual transmissions with this problem. I've had it to the dealer 3 times about it and even called subaru of America and gotten no satisfaction. They all say its "normal operation". It's so frustrating sometimes that I'm probably going to get rid of the car as soon as financially possible. It's gotten to the point of being dangerous a few times (ie. Even downshifting on a hill won't gain me any acceleration and I end up doing 35-40 on a 55mph road)
 

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I'm coming up on 12xxx on my manual trans Impreza, and I don't recall this ever being an issue. I drove it like a granny for the break-in period, keeping it at 3000rpm and below. 3000rpm in 5th is a pretty reasonable speed though. After 5k or 6k, I did notice the engine power increase. But I've never been unable to find a gear for the acceleration I wanted, after I got through the break-in period. Being good during the BiP really sucked.
 

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I do not know if Subaru does this... but some automakers program into the computer to PREVENT excessive RPMs during break-in period. Is it possible that the computer is simply preventing overrevving above 2500 RPM until some preset miles is met?


Perhaps someone with manual xmission who has over ...say 2000 miles is experiencing this issue?
 

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Yep. Over 13k, 15 minutes after my 12k service yesterday on the way home mine was doing the NO acceleration around 2500rpms. Manual transmission also. Very frustrating.
 

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There are a few of us....all with manual transmissions with this problem. I've had it to the dealer 3 times about it and even called subaru of America and gotten no satisfaction. They all say its "normal operation". It's so frustrating sometimes that I'm probably going to get rid of the car as soon as financially possible. It's gotten to the point of being dangerous a few times (ie. Even downshifting on a hill won't gain me any acceleration and I end up doing 35-40 on a 55mph road)
Sorry forgot to add. I'm at 6k miles
 

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So, I'm seriously considering going to my local dealer and showing them this thread, and the other one that illustrates this issue. They and SOA have been thus far unwilling to do anything about it, but I'm wondering if enough of us bring it to their attention if we can get them to do something.

I've narrowed it down to either a software/programming issue or something heating up and causing the computer to overcompensate. My car seems to do it more after an hour plus driving.... and then it will continue for a day or two after until whatever is causing it "resets" for lack of a better explanation, at which point it drives normally for an undetermined amount of time before doing it again.
 

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Same symptoms on my 2018 Crosstrek (same engine). Started happening sporatically but now doing it all the time between 2-3k rpm.

I emptied a bottle of Techron fuel injector cleaner into my tank this morning on the theory that the DI injectors in these cars are prone to fouling from using non-top tier brand gas. Take a look at what the direct injector's in this guy's FA20 engine look like after 17k miles. He had the same symptoms, dealer fixed by replacing injectors.

Edit: can't post the link to the thread, but you can find the photos by googling "ft86 engine bogging / stumble"
 

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I emptied a bottle of Techron fuel injector cleaner into my tank this morning on the theory that the DI injectors in these cars are prone to fouling from using non-top tier brand gas. Take a look at what the direct injector's in this guy's FA20 engine look like after 17k miles. He had the same symptoms, dealer fixed by replacing injectors.

For future reference:
Due to direct-injection into the combustion-chambers, anything you put into the gastank will NEVER touch the back of the valves where the crud collects.


The ONLY way for a 'cleaner' to get to the back of the valves would be to feed it into the intake-manifold.
 

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Same symptoms on my 2018 Crosstrek (same engine). Started happening sporatically but now doing it all the time between 2-3k rpm.

I emptied a bottle of Techron fuel injector cleaner into my tank this morning on the theory that the DI injectors in these cars are prone to fouling from using non-top tier brand gas. Take a look at what the direct injector's in this guy's FA20 engine look like after 17k miles. He had the same symptoms, dealer fixed by replacing injectors.

Edit: can't post the link to the thread, but you can find the photos by googling "ft86 engine bogging / stumble"
I assume yours is a manual trans as well?

If so, try something for me if you don't mind. Since you say yours is doing it all the time now, go for a drive and verify happening.... then flog the **** out of it for like 20 miles or so. Shift at like 4000-4500, stay in a lower gear when at highway speeds (ie. 5th or 4th) basically do an Italian tune up. Then afterwards park the car overnight and see if it still does it in the morning. I've found that when I do this (mostly cause I'm just pissed that its acting up and decide I'm gonna try to kill it) after it sits overnight it doesn't seem to do it the next day.
 

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For future reference:
Due to direct-injection into the combustion-chambers, anything you put into the gastank will NEVER touch the back of the valves where the crud collects.


The ONLY way for a 'cleaner' to get to the back of the valves would be to feed it into the intake-manifold.
That’s right. At some point down the road, I’ll probably do this treatment to clean the valves. https://m.youtube.com/watch?v=VM7tv04S1fg
 

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I assume yours is a manual trans as well?

If so, try something for me if you don't mind. Since you say yours is doing it all the time now, go for a drive and verify happening.... then flog the **** out of it for like 20 miles or so. Shift at like 4000-4500, stay in a lower gear when at highway speeds (ie. 5th or 4th) basically do an Italian tune up. Then afterwards park the car overnight and see if it still does it in the morning. I've found that when I do this (mostly cause I'm just pissed that its acting up and decide I'm gonna try to kill it) after it sits overnight it doesn't seem to do it the next day.
Yes, 6mt here. I’ve tried the Italian tune up in the past but haven’t noticed any improvement.

However, i am growing increasingly confident that the bottle of injector cleaner is doing the trick. I’ve only run half the tank, but within about 50 miles into this tank (all highway) the hesitation became much less pronounced and then gradually dissapeared over the next 50 miles. Again, I’ve only run half the tank, but so far, the issue has not returned. Feels good to be able to floor it at 1800rpm on a slight uphill and have it pull smoothly through the rev range without any bumpiness at all in acceleration.
 

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Yes, 6mt here. I’ve tried the Italian tune up in the past but haven’t noticed any improvement.

However, i am growing increasingly confident that the bottle of injector cleaner is doing the trick. I’ve only run half the tank, but within about 50 miles into this tank (all highway) the hesitation became much less pronounced and then gradually dissapeared over the next 50 miles. Again, I’ve only run half the tank, but so far, the issue has not returned. Feels good to be able to floor it at 1800rpm on a slight uphill and have it pull smoothly through the rev range without any bumpiness at all in acceleration.
What did you use exactly? I'd like to try this out as well?
 
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