I plan on buying a 2019 6MT soon and have read about this issue on this forum, the Imoreza 5 forum, Forester forum and reddit.

One potential remedy I did not see mentioned on this forum or your list is motor oil rated SN Plus, which helps low speed preignition. This was in the Forester forum and in a YouTube video. I believe I read where some have had the problem disappear temporarily after an oil change.

 

I used is Mobil 1 which is listed as an SN Plus rated oil

 

You should start by putting the stock air intake back on. I have had experience with previous cars that the maf sensor can be a bit sensitive without a tune. I can't speak for the crosstrek yet but I would suggest you begin there.

 

The only I have there is that the intake has been on since the car had ~60 miles on it. Can't imagine the MAF taking 5100 miles to catch up and be saying "wait a second, you don't belong here."

 

Dang!


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I think your issue is the heatsoaked intake, the original plastic intake resists heat radiation better than the metal ssd intake. For my case, I use AEM and it shows similar hesitation during stop and go traffic, and finally I put heatshield on intake to reduce the temperature. It did not address 100% but reduce temperature and make the hesitation unlikely happen

 

just did a round trip to mammoth (600mi and 1,200 ft to +9,000 ft elevation... if you are planning to pass, go up hill or accelerate and you are not above 3.5k you're gonna have a bad day. this engine/transmission is not for the faint of heart. when trying to maintain 65mph and a slight grade is ahead i MUST downshift to 5th. if it's more than a slight grade, then 4th here I come. I just went up the portal to mount Whitney and had to use 2nd gear for a good 5-6 miles. this is our lives now [emoji23] unless where you're at is flat.

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I went from the bay area to mammoth last week. I do this several times a year. each day I went into the white mountains for photography (more than 11k '). I was alone twice and once I had a passenger. big difference. I drive by myself 99.5% of the time and have never had anyone in the back seat. if you're travelling with 2 or more passengers I can see this being the wrong car for you.

 

I’ve had the same issue since day 1. However, note that it’s worse some days than most. That said, gentle acceleration in 2nd, 3rd and 4th is nearly a road hazard between approximately 2.3-3.5k rpm.
I don’t use my AC so I have no idea if that makes it worse.
I’d love to have resolution but like a kid with asthma, I just accept that that’s the way it is.


Hmmm... maybe some sort of inhaler strapped to the intake manifold? :grin:

 

Any videos? Not sure if my 6MT does this or not.

 

If you are driving normally on a hot day with A/C on and shift from first to second without keeping revs above say 2.5k you will push the pedal down to accelerate in 2nd but the engine hesitates or acts like it’s misfiring but slowly will pull up to the desired RPM until that 2.5/3k range and then it will start revving like normal again.
I double checked with scan tool and live data they are simply not giving the engine fuel as the pedal sensors and everything else are fine, it is just tuned to cut fuel at bad times it seems.

 

Well that's just dumb. So basically rev the hell out of it if I want to use my ac.

 

my a/c will cut off if im climbing and above 4.5k rpm [emoji23]

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I just want to jump in and say I have this exact same issue. I have a 18 manual and for me it's between 2k and 3k rpm once I get past 3 she has "pep". I'm fully stock and live in Florida. So your high humidity and temperature ideas ring true with me. I have a hard time consistently reproducing the problem so I haven't talked to the dealership about it yet.

 

As of right now, even without the AC on, I'm still getting the issue

 

at times i feel a lack of power when shifting with the AC on for sure. i like the car just fine. i don't think it is a race car and the RPM's have to monitored accordingly.i have not been on any steep inclines yet but imagine a lot of downshifting will be necessary.

 

6MT here. 23k miles on my 2018. Having the same issues with bogging when accelerating. Extremely frustrating, no check engine light and no codes. After keeping an OBD scanner on it for quite some time I noticed that under acceleration the MAF readings were fluctuating by 20 to 30 g/s with the throttle steady at wide open. Thought for sure that was my problem. Replaced MAF and still having exact same symptoms. Mine is bad, stutters and jerks and falls flat when accelerating. I've had it to the dealer twice and they can't recreate. I'm hoping someone gets to the bottom of this. I plan on driving it to dealer when acting up to have them ride along.

 

any of you manual guys have any oil residue on the rear side of your oil pan? above the drain bolt?

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N

Not that I know of but will check. Do you think this may be a clue to what's going on or is this an unrelated issue you are experiencing?

 

FWIW I had a 2015 XV that had similar behavior; it was flat until maybe 2.5-3k rpm then it would finally wake up (mine was a 5MT). My solution was to keep revs above 2.5-3k when trying to do anything, basically. I got rid of my XV a couple years ago and find myself swinging back to one again, so it's interesting to see that it wasn't just me noticing the lack of power/torque below 2.5/3k rpm..

 

Thanks Evil_ed. My problem goes a little beyond low power. It bucks and surges during acceleration. I've been monitoring with an OBDII scanner and when it acts up the timing advance goes negative very quickly. Also under acceleration the MAF sensor fluctuates back and forth from 65 g/s to the twenties. No check engine codes or lights. I've changed MAF out and symptoms did not change. Changed fuel to top tier 93 and no change. I'm starting to think I have a knock sensor issue or electronic throttle issue. Hopefully someone on these forums has encountered and solved a similar issue. Fingers crossed.

 

I've been monitoring with an OBDII scanner and when it acts up the timing advance goes negative very quickly.

That's your clue right there.Pulling timing will reduce the power from any engine.Doing so on a small,low power engine like this will make that effect even more pronounced.The only reason that the ECU would pull timing is if preignition/knock is detected.The knock sensor is sending a false alarm to the ECU.It doesn't trigger a code because the sensor hasn't actually failed.It's just sending bad information.As mentioned in the thread that Astrokats linked to,as well as in the Forester forum,a new knock sensor is the fix.If you are still under warranty then describe your issue to the dealer.Make sure that it's logged in their computer that you believe the knock sensor is to blame due to the changes in ignition timing.If they refuse to change it because there's no codes to confirm the issue then have it done somewhere else and bring the bill back to the dealer to get that money refunded.

 

Ahh, yes that is different; I didn't have any surging/bucking issues with mine. The only change I made to mine was I swapped out the engine air filter for an AEM reusable one (non-oiled), though my understanding was that the factory air filter wasn't horrible either. I didn't mess with any intakes or exhausts because I've read that Subarus are unusually sensitive to air in/air out changes. It might be an ECU issue, maybe? A factory screwup?

 

Am having similar engine 'hesitation" problems. It started a few days ago, very infrequent but more or less on every gear of my 2018 6MT Premium 21,000 miles. Had service appointment today for HU and on my way there the car was running smooth, nothing whatsoever. Surprise, surprise. I asked for a check up, but they just took the car for a ride and came back with the same result as mine today: no problem.

Hopefully they didn't cause any damages to clutch/engine etc, I've forgotten to turn my dashcam off so now I know that they rode my car like they would in the NASCAR trials. Saved the dashcam recording to PC just in case.

So I'm puzzled about the engine stutter, that day when I first noticed it was very, very hot. Will see.

 

I have a 2019 CrossTrek, base model with the 6MT. I get this same issue and it's making me crazy. I drive 100 miles per day and it's so intermittent I haven't been able to nail down the conditions that cause it. Where can I get a scanner to monitor this because, when it happens, there's no "check engine" light that comes on so it's not "throwing codes" such that it would show up.

Has anyone pushed this issue with a corporate level above their dealership?

 

I have a 2019 CrossTrek, base model with the 6MT. I get this same issue and it's making me crazy. I drive 100 miles per day and it's so intermittent I haven't been able to nail down the conditions that cause it. Where can I get a scanner to monitor this because, when it happens, there's no "check engine" light that comes on so it's not "throwing codes" such that it would show up.

Has anyone pushed this issue with a corporate level above their dealership?

I use the Torque Pro app with a cheap Amazon bluetooth OBDII device. Whole setup ran about 20 bucks. I think it works great, lots of capability.

 

I'm about to......writing to SOA tonight. I'll keep all posted on response. Wouldn't hurt for us all to do it I suppose.

 

I wrote to them, waiting for a response. I will update this thread when I hear back.

 

Wanted to close the loop on my experiences. I believe my bogging issues were caused by overfilling of the oil when the dealer was doing service. The outgoing 2.0 had a larger oil capacity than the 2018 which I believe was a contributor. Since I started changing my own the problem has not come back. Hope this helps someone in the future.

 

Have you taken the car in for this new pcv replacement recall? If I understand the recall this pcv valve is broken and allowing oil into the combustion chamber from time to time and that could cause the missfire feeling we're experiencing. I'm going to try and take mine in for the inspection next week.

 

There haven't been any reports here yet of a PCV valve actually being broken. It seems like it's more of a precautionary recall. Also, if the valve did break off it wouldn't let oil in - quite the opposite...

 

2018 6MT. I've experienced all of the symptoms mentioned in this thread. Right now, however, it's running great. Why? Because it's winter.
I've tracked this long enough to expect it to happen when it's hot outside. From October through April I have no problems, but when the weather heats up, the symptoms return. Having the A/C on will make it worse, but that may just be because the A/C draws a few HP away. Overall, if it's hot, the symptoms are there, whether the A/C is on or not.
Please don't confuse this problem with a lack of power. The engine is always weak, and that's something you know you have to deal with in this model. The bottom line is: the engine performs very differently on hot days than on cool days.

 

2018 6MT. I've experienced all of the symptoms mentioned in this thread. Right now, however, it's running great. Why? Because it's winter.
I've tracked this long enough to expect it to happen when it's hot outside. From October through April I have no problems, but when the weather heats up, the symptoms return. Having the A/C on will make it worse, but that may just be because the A/C draws a few HP away. Overall, if it's hot, the symptoms are there, whether the A/C is on or not.
Please don't confuse this problem with a lack of power. The engine is always weak, and that's something you know you have to deal with in this model. The bottom line is: the engine performs very differently on hot days than on cool days.

This echoes my sentiments and experiences exactly.

 

I have a 2018 manual premium. I drive in upstate NY and have the exact same issues to the T. I suspected it was humidity and that it was fuel mixture related, not mechanical. I contacted the dealership and was told that they had never heard of any issues. Of coarse... I have 15k miles on it now and it is getting no better or worse. If anyone has a definitive answer please let me know!

 

Welcome! There's a similar thread here that might be helpful: Model Year 2018 and Newer - Loss of power

Is yours seasonal?

 

Is yours seasonal?
[/QUOTE]
It seems to be. Last year was a dry winter so not that noticeable. This year we’ve had 40 degree days with rain for that last 2 months and it has been noticeable. Definitely summer prominent though. If enough of us scream they’ll probably come out with a new reprogram.

 

Yep, that came up in the other thread, too....