Low RPM/Speed Jerking/shaking on 2011 Impreza Outback Sport

[Deehorg]

So my car was bought one owner 3 months ago with 65,350 miles and now it has 68,400 miles. A week or two after I bought it it began doing this random jerking/shaking when I'm driving like 20 mph or so. It even did not once when my foot wasn't on the pedal. It's an automatic transmission. It doesn't do it all the time but from my observation it only does it in the first 20 minutes the cars been running. It is a very noticeable shaking/jerking feeling in the whole entire car. I talked to a Subaru mechanic and he said that it could be the fact that my transmission fluid seemed to be thinner than normal but still ok just likely in need of a change, and also could list likely be spark plug/cool pack related. I've also read tranny solenoid could be out. I'm praying to dear Jesus it's nothing serious and transmission related. Sometimes the car like randomly jerks forward when going from a real low gear low rpm to a higher one but basically doesn't happen when I stomp on it. Sometimes more noticeable going up a hill. Was told that was likely normal transmission. But this jerking/jolting is something I'm hoping will go away when I service it in 2 weeks. Anyone know what could be causing it? Thanks in advance!

[1 Lucky Texan]

from whom did you buy it? If there's any chance someone unfamiliar with Subarus worked on it before the sale - they could easily have used an incorrect fluid in the trans. 3 drain/fill/drive cycles with Subaru ATF-HP (or w'ever they call it) would get you around 85% new fluid I think (I might be a little off, you have a 5EAT right?)

 

also, the car MUST have 4 tires that match, same brand/model/wear level. The more the tires vary from each other, the more likely you will have torque bind.

[Deehorg]

Tires are newer Michellins with at least half

Life left. I bought it used from an Audi Porsche dealer and it looked very well maintained/clean. I'm due for the service and when I have it done in

Going to address it. I just hope it goes away. Cheaply. Lol. It seems more than tires as the whole car shakes back and forth about 1-4 or 5 times and it does look like the tach is fluxing rapidly when it happens. And it only seems to do it in first 20 mins and low Speed. I've always owned American cars so I'm a little annoyed. I'm

Guessing if this happens in snow/ice it could be bad news.

[wtdash]

Hi,

Do the 60K service. Preferably @ a Subie shop - indie is OK vs. dealer$hip.

 

Also, if you didn't get a CARFAX from the dealer (not an Autocheck), order one up as it MAY show the car's service history.

 

FWIW, Most Subarus sold in the US are built in the US, AFAIK.

 

GL,

TD

[1 Lucky Texan]

Impreza Outback? if the VIN starts with a 4, US, if with a J, Japan I think.

 

I suppose a u-joint or other drivetrain problem could cause what you're sensing. Seems early for that kind of failure unless the car was abused.

Edited October 14, 2016 by 1 Lucky Texan

[Deehorg]

Funny thing is that the service records were perfect, minus the 60k service. Guy who owned it was a university geography professor so he did everything but the 60k service likely because he was trading it in right thereafter. I'm hoping the subie mechanic was right and it just needs a fluid replacement and some coil packs and it's all set. Praying. Thanks everyone! I'm hoping it's not a tranny issue. I mentioned it to my used car manager at my dealership and he sees a spoob to of used cars after 30 years of running an auction and he said these aren't known for tranny issues. Hoping whatever it is goes away.

[Deehorg]

Yea J is Japan and like 3 is Mexican

[1 Lucky Texan]

read a LOT of posts across multiple Forums for years - only ever read of one bad coil-on-plug type coil. very uncommon if your car has c.o.p. type for one to be bad. Swapping it with another cylinder to see if the misfire follows would bea good diagnostic procedure.

 

if someone serviced the car and installed other than NGK plugs - I'd change those before any coil.

 

if there is oil in the plug 'tubes', could be a leaky valve cover gasket.

 

 

are you getting a CEL for misfires?

Edited October 14, 2016 by 1 Lucky Texan

[Deehorg]

Not CEL at all. That's what my mechanic just said at my Mazda/GMC dealer said. He also said what I read on another forum about how sometimes it's just a computer flash/update to the TCU. They also said it could be my torque converter or something. More importantly he said what it needs it a subie diagnostic tool to address what it is instead of speculating and self diagnosing. Hahaha

[1 Lucky Texan]

well, there's no doubt good first-hand diagnosis by a trained tech with proper equipment has value.

 

but, given some of the unknowns with a new-to-you used car - there's not much could be lost in double checking some common areas  where confusion or laziness could lead to improper parts, fluids or installation techniques that might cause issues. Some things on these cars can be cheap aftermarket - like knock sensors, other stuff NEEDS to be OEM or specific suppliers like spark plugs. And, due to the AWD design of the transmission, some techs can be easily confused and drain/fill improper fluids. Front diffs drained and dry, or filled with transmission fluid, etc.

 

not sure your level of DIY comfort, there are online guides and youtube videos showing how to service most of the areas we've discussed. You can also post a request in a new thread for a soob-experienced indie. mech. near your city. That might be a good place to take the car when you've exhausted the 'easy' stuff.

Edited October 14, 2016 by 1 Lucky Texan

[Deehorg]

Right on. I can't wait to have Subaru give a clear diagnosis in a few weeks. It's pretty uneasy to experience a quick shake back and fourth. it's my first financed car so to have issues at all when I've always bought American cars for less than $2,600 and drove them into the ground with no issues sucks. Bought a Subaru to not have these issues.

[1 Lucky Texan]

any 5 year old car could have problems. Subarus are no exception.