Rough idle, slight miss at low rpm

I own a new 08 Legacy 2.5i Auto. It now has 3000 miles. I traded an identical 2006 Legacy for it (with 40k miles). My new 08 seems to have a rough idle after warming up and gets worse when the a/c is on, or cycles on and off. This is especially noticable when idling in traffic when slightly pressing the brake- it does what seems like a bumping when rolling under 5 mph. It also sometimes has slight miss when downshifting at low rpm's and even seems to jerk when something catches- (I assume torque converter lock/unlock- but it shouldn't be this noticable). I've definitely noticed that it accelerates significantly slower than my '06 and the shift points are very different- it shifts much earlier under light acceleration. If anyone has any insight on what may be the cause of this, I'd like your input. My first visit to the dealer: Said they everything checked out on the computer and it doesn't show any problem-(of course). I called another dealer and was told, "Well these engines aren't the smoothest." I proceeded to tell him that my 06 was so smooth that I'd sometimes grind the starter while it was parked idling because I couldn't hear nor feel the engine running. There is NO mistaking when my 08 is running!!! I still haven't taken it back in. I suspect one of 3 causes of this: 1) cracked, defective or otherwise malfunctioning spark plug. 2) clogged or otherwise malfunctioning injector. 3) Bad flash program update. PLEASE ADVISE

I have an 08 Legacy 2.5i Auto Ltd. There is no mistaking my car starting up. Once it gets warm though its ok. I do find that at stoplights it idles a little rough, but I have had other Subaru owners in the car and they tell me that's normal for a Subaru. I do notice the shift points are different, I actually like where the shift points are driving normally.

I agree, there's absolutely nothing quiet or smooth about a cold startup on the Subaru 2.5, I know that's normal. But mine actually seems smoother in that warmup mode and higher rpms, than at warm idle. Maybe this is normal and I was just lucky to have a very smooth-running 2006 model. I would love to have my 2006's powertrain in this '08.

 

My only other gripe about this car is the driver's side headrest. Does anyone else's headrest keep creeping up? My '06 did the same thing! Since I'm only 5'8, I like the headrest in the down position, but after a few minutes of driving, it moves itself to the middle position or higher. I have addressed this many times with my '06 and the dealer was never able to find a fix. Since my 08 does it even worse, I think I will press further. They even tried switching the pass/driver side headrests and the driver's one still moved up, meaning the problem is in the seat.

This is especially noticable when idling in traffic when slightly pressing the brake- it does what seems like a bumping when rolling around 5-10 mph.

 

This caught my attention as what you describe sounds similar to what I have noticed on my 08 2.5I 4eat. I posted about it and didn't get much response but what I notice on my car is I feel amost a slight shaking / jerkyness in the drive train if I get the car to move as slow as possible. Like in bumper to bumper traffic, when you are stoped but have to move your car forward just a few feet at a time, when I slowly release the brake to get my car to crawl forward I feel this... But once I fully release the brake and the car gets moving a little faster it smooths out... Is this what your feeling?

Yes, this is exactly what I am feeling. And my new 2006 never did this because I would have surely noticed, since I put 35k miles on it in 18 months. I'm beginning to think all my '08 drivetrain complaints are caused by an obvious reprogram sometime after my '06 model. Does your car also have a slight shake when idling in park (at normal operating temperature)? I even opened the hood and put my hand on the top of the engine to feel the shake.

 

I just confirmed another annoying difference today. I'm not sure how hard you run your car, but I've found what seems to be an error in programming, whether it be the engine or transmission software. If I'm manually shifting the car from 1st to 2nd gear and shift it right before 6000 rpm (redline is 6400), it will jump to 3rd gear instead. I will bring this to the dealer's attention (God help me- the dealers here aren't the best) and hopefully they can have Subaru include a fix in an update. I may take it in this Friday (May 16) and I will post my results here.

I havn't ran the up to that high an rpm before I shift to notice that other issue. I do notice the engine shake a bit when at Idle in park. I think i notice it more on a cold start up. When the car starts it idles at about 1500 rpm. Ill usually let it warm up a bit, and then tap the gas slightly so the RMS drop down. When I let it idle there I notice the shake a bit more vs if it was fully warmed up. The shakyness I feel when I creep the car forward is the most concerning to me... It scares me that something might not be right, but Im happy to find another who seems to notice it. Besure to let us know what they think if you take it in and I'll do the same. I am going to mention it on my next oil change.

more start up is rough too. also do you guys hear tinging when you turn the car off? i think its the cat.

 

ps in manual mode the car will shift around 6100 to prevent redlining the car. there have times i have been in first and waited to long to shift to second. it then would shift to second then third. you are better just shifting at 6000 rpms

more start up is rough too. also do you guys hear tinging when you turn the car off? i think its the cat.

 

ps in manual mode the car will shift around 6100 to prevent redlining the car. there have times i have been in first and waited to long to shift to second. it then would shift to second then third. you are better just shifting at 6000 rpms

As I've said above, I have shifted just short of 6000rpm and it still skips a gear, meaning it was preparing to shift itself just before I did. I think this is an error in programming, or just a bad decision on part of whomever changed the shift points. The engine controls already have a rev-limiter around 6400rpm (?), so I think to make the car shift 600rpm before the redline is being a little redundant.

i will say that ive been shifting by feel and sound vs tac. it sounds stupid it feels smoother shifting ive driven a few different 2008 2.5s and i can say its all cars, not just yours so dont worry that you might have a bad car

i will say that ive been shifting by feel and sound vs tac. it sounds stupid it feels smoother shifting ive driven a few different 2008 2.5s and i can say its all cars, not just yours so dont worry that you might have a bad car

 

Thanks for the info. I was wanting to hear more from others who had driven '08 2.5's. I was beginning to think mine was built on a Friday afternoon since it also has minor body/interior issues that my '06 didn't.

 

I went to the service dept yesterday. The Subaru tech here is a real a$$. Just to tell him my Subaru has any problem puts him on the defensive. He claimed the shift issue didn't exist, but refused to ride with me to show him. He claims that the engine/transmission management software changes are because all 08's are PZEV vehicles. I highly doubt this since I've seen other 08's with a PZEV badge on the back, and mine doesn't have one. He also said the car has to break in and would get smoother (I doubt that also). If anyone knows about the PZEV info, please advise

 

I did confirm after leaving the Subaru service Dept that if I manually shift from 1st to 2nd anywhere after 5500rpm, it jumps to 3rd gear. That's just wrong, no matter what the tech says. I will be writing Subaru about it.

 

Would you believe I've been to all 3 Subaru service depts in south La and this is the best of the 3. I think SIA (SOA) would do much better as a company if they would make their dealers/service depts more accountable, or just be more customer friendly in general. All 3 have been the worst customer service I've experienced at ANY service dept, ever! (I've dealt mostly with Chevy (other GM), Ford, Honda, Toyota dealers in the past)

I had taken the car in for the 4th and final time about this hesitation/rough drivetrain behavior. A Subaru rep came down, drove the car and said this was normal. If it is indeed normal, I find it unacceptable for a new car. Although I drove another 08 which did not exibit this behavior, I've spoken with many '08 2.5i owners who have the same issue. The rep also said the very low-speed bumping feeling was normal- some bs about normal drivetrain stuff coming through- if I had the service invoice here, I'd quote it exactly. So I traded it on a new '09 3.0R which seems to be fine so far except for a buzz in the door caused by the H/K's bass, and the trunk panel being slightly out of alignment. But that's all for another thread.