[jeff311omaha]

If you can replicate that on purpose that would help a lot to diagnose the actual issue.. or at least confirm it exist
Your symptoms are also in line with severe Case or what’s going on in this thread

Throttle Calibration PDF

So I'd felt some odd jerkiness in acceleration and remembered seeing someone on these forums had mentioned and posted a link to a PDF with easy steps on how to calibrate the throttle to one's foot action and how evenly your foot moves the throttle (pedal). Anyway, a week ago I finally got...

www.subaruoutback.org

Yeah, it'd be very useful if I could replicate it. I can't. They can't. Here we are.

 

[AvidHiker]

I doubt there's anything inexpensive for DIY logging of truly useful data on a Gen 6. Logging stopped being a simple affair when Subaru switched ECM manufacturers for Gen 5 (at least from what I've read).

 

[GirchyGirchy]

I doubt there's anything inexpensive for DIY logging of truly useful data on a Gen 6. Logging stopped being a simple affair when Subaru switched ECM manufacturers for Gen 5 (at least from what I've read).

There should be no reason a normal OBD2 adapter can't pick up the normal PIDs and log them.

 

[AvidHiker]

There should be no reason a normal OBD2 adapter can't pick up the normal PIDs and log them.

Yeah, I guess my question is whether or not anything relevant could be logged. I think a lot of what you used to be able to log from the ECM is inaccessible to cheap tools (which had once been possible using free software and a special cable). I've heard Bluedriver has better logging capabilities for Gen 5s compared with the cheap tools but still not sure how much it has access to.

 

[Fujisawa]

This is among the most scary car problems you can have and my parents did, indeed, once get rid of a car (Cutlass Cierra, terrible car) whose carburetor would inexplicably lead to fuel loss while turning left into traffic. Make noise with the dealer and Subaru. Tell them you can't drive the car the way it is. You may or may not get anywhere, but it could be the only way to make progress. Sell if it doesn't get anywhere. If you are up for some lengthy and (very careful!) real world testing you might be able to figure it out, but only some people have time in their life for that.

Some guesses:

Transmission control module or actuator (these have a clutch or clutches right?)
Throttle position sensor
Fuel pump or blockage

Here is a quick thing to try. The top most panel on your dash infotainment can be configured with three vehicle info readouts. Not many options. But one of them is throttle position. Put that up on the display and leave it there. I don't know if it's commanded or actual position, but if you push the gas pedal down and that % doesn't change, or it does change when it shouldn't, you have found something out.

 

[jeff311omaha]

This is among the most scary car problems you can have and my parents did, indeed, once get rid of a car (Cutlass Cierra, terrible car) whose carburetor would inexplicably lead to fuel loss while turning left into traffic. Make noise with the dealer and Subaru. Tell them you can't drive the car the way it is. You may or may not get anywhere, but it could be the only way to make progress. Sell if it doesn't get anywhere. If you are up for some lengthy and (very careful!) real world testing you might be able to figure it out, but only some people have time in their life for that.

Some guesses:

Transmission control module or actuator (these have a clutch or clutches right?)
Throttle position sensor
Fuel pump or blockage

Here is a quick thing to try. The top most panel on your dash infotainment can be configured with three vehicle info readouts. Not many options. But one of them is throttle position. Put that up on the display and leave it there. I don't know if it's commanded or actual position, but if you push the gas pedal down and that % doesn't change, or it does change when it shouldn't, you have found something out.

It's so sporadic that I don't see how I could test for it to be honest. I dropped it off with the hope that they immediately knew what the problem was based on my symptoms because I 100% knew for a fact that the tech wouldn't be able to replicate the issue. The moment they started blaming me getting my oil changed elsewhere I knew it was going to be a bumpy ride.

I didn't hear back from them yesterday, so I'm assuming that no new is not good news. We'll see. I have a loaner that they'll eventually want back! I have a 23 or 24 Crosstrek that has an oddly buttery smooth identical engine/transmission combo that seems faster and definitely gets better gas mileage than my lighter 2020 Legacy.

 

[jeff311omaha]

Just got the call back from the dealership.

While they were not able to replicate the initial issue, they are confident that "resolving the oil issue" will fix the "My car is trying to kill me" problem. The tech stated that it essentially felt like a different car once they did that. As someone who has driven that car for over 4 years I can say that it's been the same joyless vehicle to drive before and after this problem (let alone my most recent oil change), so I AM EXTREMELY EXCITED to see how my car has magically been rejuvenated by "resolving the oil issue" that they claim happened when I got my oil changed a couple weeks ago. They also did a transmission relearn, so that's fun.

Needles to say, I am dubious.

 

[Fujisawa]

I can see how you would be dubious. It is true that overfilling can cause driveability problems, I think Subaru has put out some info on that even, but .. idk. Hopefully it does resolve your problem. Presumably your last oil change is somewhere in the recent past, and i think it was happening before?

If it hasn't been suggested yet, go Google a diagram of the various grounding locations in the engine bay - which is to say, all the places where the electrical system is connected to the unibody. Occasionally having one loose can cause very random and frustrating electrical problems. Is this likely, no, but a few minutes securing them all with a small wrench will at least rule it out for the future.

 

[SilverOnyx]

Subaru has put out a tech tips saying that overfilling can cause drivability issues, however the description of the problem that @jeff311omaha experienced intermittently but present over a span across multiple oil changes makes me think that unless the car was consistently overfilled then the problem didn't start with overfilled oil and it's not likely the root cause. The techtips article is attached as a PDF.

Other: - TechTIPS on overfilling engine oil; &amp...

Was looking through recent issues of Subaru TechTIPs, and in both the March and July 2013 issues there was this article about "Too Much Oil in the Engine": How much is too much? What can happen if you put too much oil in an engine? If you’ve ever seen an engine that had way too much oil added...

www.subaruoutback.org

 

[Ali Pine]

Just got the call back from the dealership.

Needles to say, I am dubious.

Please keep this thread updated as to your 'issue'.

 

[jeff311omaha]

In reference to the tech saying it felt like a completely different car, it most certainly doesn't feel any different.

I'll update this if and when it happens again, so I hope this is my last post here!

Well.. if I get t-boned and die this could be my last post as well, so...

 

[Rich Werner]

About a year ago (I'm guessing) I had a bizarre issue when leaving a 4-way stop in a neighborhood. As I pressed down on the accelerator, the car seemed to simply idle/crawl into the intersection at what sounded like the lowest possible RPM for 1 or 2 full seconds. For the next 1-2 seconds, I started pumping the accelerator out of confusion wondering wtf was happening, never flooring it completely. Out of nowhere the engine bounced off of the rev limiter 5 or 6 times (still not even close to floored, still happens with pedal completely depressed once this process starts) and then came back down to "normal" and began to accelerate normally like nothing happened. No check engine light, no weirdness, no nothin'. I thought to myself, "Gee, if I was turning left at a busy intersection I'd be dead."

This has happened about once every month or two ever since and doesn't seem to have any rhyme or reason to it. It's never happened to me within a few blocks from home or work, so it doesn't appear to be a cold start thing or not. It doesn't seem to happen immediately after getting a new tank of gas either.

After the 2nd or 3rd time it happened I ended up talking to Subaru service at my dealership and they wanted me to make sure I didn't accidentally bump the shifter into manual or neutral mode (okay) and to keep an eye on things if it happened again.

Well, last week it DID happen again while I was turning left in front of traffic. Nothing yeehaw or anything, just a normal left turn. If the driver that swerved like a BOSS hadn't been paying attention I would have gotten absolutely demolished in a massive t-bone wreck that I would have 100% been at fault for. I immediately pulled into a parking lot and called my dealership and told them that they needed to look at it ASAP.

I was able to drop it off and get a loaner on Friday after detailing the symptoms. I did indicate numerous times that I hoped the symptoms immediately mean something to them since it would be nearly impossible to replicate by the tech.

FWIW, I am the original owner and opted for the most expensive available warranty after I bought my car after the lease was up. After clearly articulating what the problem was, they sent me on my way with a loaner. Friday afternoon they called me up and told me that there was an overfill 1.5 quarts of oil in my car which could be the problem or part of the problem. I JUST switched back to getting oil changed at "my mechanic" 4 or 5 months earlier, including an oil change that was done the previous week. They indicated that this could be part of the problem and could affect how the warranty work would be covered but also said that they didn't yet know what the issue was because they weren't able to replicate the issue. When I reminded them that they performed the oil change immediately before my initial call-in pertaining to this, they still said that they would need to perform a correct fresh oil change ($80 on me) so they could begin accurately diagnosing the issue.

I called my mechanic (who I would literally trust with my life) up to let him know what was going on and he immediately called BS. "They saw the oil change sticker and it didn't say Subaru. They're looking for a way out." He said that he'd be happy to get it back to "normal levels" free of charge if I grabbed it from Subaru and took it straight to his shop, also pointing out that there's no way there was an extra quart and a half in it when it left his shop, but there sure as hell would be now if Subaru was OK with me picking it up so he could correct the issue for free.

I asked the service writer at Subaru if I could just pick it back up so my mechanic could "correct his error" and they decided to simply take care of it on the house so they could continue diagnosing the main issue.

1) Does anyone have any idea what my initial problem could be? I was shocked that the symptoms weren't immediately an indicator of a known issue.

2) My mechanic literally has one of the best shops in town and he swears up and down that there's zero chance that he made a mistake on something as mundane as an oil change. Is this a tactic that anyone has ever heard of before or is it simply likely that he made a mistake and it has no bearing on my issue?

My father-in-law experienced this problem and when I was riding with him I saw that he drove with left foot brake and right foot throttle. He has his left foot on the brake and pushing on the accelerator at the same time with his right foot. In getting ready to turn, he would step on the accellerator a bit more and then release the brake. As soon as he released the brake and started to turn the car stumbled and took awhile to get going again. I was able to duplicate this on my 2020 as well.

 

[jeff311omaha]

My father-in-law experienced this problem and when I was riding with him I saw that he drove with left foot brake and right foot throttle. He has his left foot on the brake and pushing on the accelerator at the same time with his right foot. In getting ready to turn, he would step on the accellerator a bit more and then release the brake. As soon as he released the brake and started to turn the car stumbled and took awhile to get going again. I was able to duplicate this on my 2020 as well.

Interesting...

I drive conventionally, so this is an unrelated problem. 2-footed driving is dangerous aaaaaffffff.

 

[Douglas Thomas]

A long shot but have the Subaru Dealer check the CVT and Front Differential fluid levels.
Possibly CVT fluid is low or differential seal leaked and allowed its fluid to mix with the CVT fluid.

 

[jeff311omaha]

I'm assuming they were elbow deep into everything pertaining to the transmission for what it's worth. Honestly I can't speak to any of the specifics other than the very limited information that they gave me. They did have it for a few days where I just straight up didn't hear from them and I'm pretty sure they were aware that this had the potential to be a big problem so they had more than one set of eyes on it.

 

[Jeff DeTray]

I had a similar problem with my 2013 Outback, soon after I bought it. The car has a CVT transmission.

The car would periodically -- and apparently randomly -- switch itself into its so-called "limp" mode. The engine continued to run but at very low RPM, as if the car was at idle. It did not respond at all to the accelerator. It would merely limp along at a crawl.

I discovered that pulling over, turning off the ignition, then immediately re-starting the car returned it to normal operation, until the next occurence. Shortly thereafter, I discovered that placing the transmission momentarily into Neutral also returned the car to normal operation.

This problem occurred as often as 4-5 times per day, but occasionally did not occur for a two or three weeks. The problem usually occurred at low speeds -- under 35 MPH. But on one unhappy occasion it happened on a busy two-lane highway at 65 MPH. Not fun.

The dealer never found a problem. The car never threw any codes, even when it went into limp mode only a few blocks from my dealer. The dealer tried to blame it on improper installation of my hand controls, but I've driven with the same type of hand controls for 50 years and knew it could not be the cause.

This annoyance persisted for nearly a year including two firmware updates by the dealer, then magically went away after a third firmware update. Subaru never acknowledged a problem with the car. I am still driving the car 11 years later, with the same set of hand controls, and the problem has never recurred.

- Jeff

 

[Lowobsti]

if i recall, some cvt vehicles 2010-2012 had a similar issue where the torque converter was too locked up to accelerate , like starting out in 4th gear with a manual trans) ,and some stalling conditions. This was caused by a seal getting damaged and bypassing fluid. No external leaking. Just a possibility . If your problem is magically fixed, it was due to cvt programing and not oil change imho.

 

[Babyjaycol]

Man, you REALLY need to get rid of/stop driving that car. Yesterday. No one at Subaru, your insurance, or really any business cares about you as much as the people in your life. If you are killed/injured/maimed, there’s no replacing YOU or returning your body to complete health for the rest of your life.

Even crushing an ankle or breaking up a knee or shoulder will cause you pain and lower your wellbeing forever. Not to mention the medical costs/time from work and LIFE that Subaru will not cover fully.

No amount of lawsuit $ will replace any of that. You will be a statistic for damage control; car companies let a certain amount of deaths/injuries occur before they even address a problem. Remember the Toyotas (?) that would accelerate out of control with no way to stop them? A LOT of people had to be affected before they did anything. Bean counters/damage control don’t care about one case.

Instead of yourself, imagine that the person you love MOST in this world drives your car one day (even if it’s your dog like the Subaru commercials lol) and are killed/injured/maimed. We all take risks for ourselves at times, brush them off. But we usually don’t want our loved ones to take the same risks.

Please do not drive this car one more day. In fact, I don’t know at all, but perhaps speak to an attorney and get him to write all of this down so it’s recorded, and send them a letter about it. Recording that they knew about it a long time. And perhaps they need to give you enough $ to buy a replacement.

 

[Babyjaycol]

This is not a known issue on the forum but only a small minority of owners make their way here. I'd make an NHSTA report, and if they can't properly diagnose and fix the problem, get rid of the car.

Report a Safety Problem | NHTSA

File a complaint with NHTSA if you experienced a vehicle, tire, car seat or equipment safety problem that could be a safety defect.

www.nhtsa.gov

I'd also call Subaru of America and express how alarmed you are at this issue and that the dealership is claiming that they can't reproduce this intermittent yet dangerous issue and ask them to help the dealership figure this out.

I presume you don't have a throttle controller or anything? I'd wonder if the throttle itself is having an issue where it's not consistently providing clean inputs to the ECU for the drive by wire system, so that the throttle body butterfly isn't responding, or some other electrical/electronic issue.

YES! NHSTA! And stop driving that car IMMEDIATELY.

 

[Babyjaycol]

There's no chance there was extra oil in the car, regardless of the fact that a mechanic could hypothetically leave a wrench in your engine bay. This issue happened when Subaru was changing my oil when it was still under my lease. I understand the concept of double checking the mechanics work, but realistically that's not something I'm likely going to do when it comes to any skilled professional. I paid them because they know what they're doing.

Everyone is human and is capable of making a mistake. I’m so happy for you having such an awesome mechanic though! If you’re in Mississippi I’d love to know who it is lol!