Subaru Outback Owners

thunderboltthunderbolt Member Posts: 5,909 ✭✭✭
I know this is a gun forum, but here's a car question for Subaru owners.  I'm having a problem with a 2006 Subaru Outback with around 170,000 miles on it.  Shifts fine on flat grades. Going up steeper grades, it's like the gas pedal cuts off at 40 mph.  The vehicle slows to a crawl until I reach the top of the hill, then returns to normal.  Downshifts itself (automatic transmission) until it creeps along at 5-10 mph.   Only recent code is evap system which won't cause any problems, so I'm told.   I've replaced oil pressure sensor, fuel pump and catalytic converter recently.  Normally I get 200,000 plus miles out of an Outback before it gives up.  Transmission fluid full and red.  If I use sport mode to shift manually, I might get a little farther before the gas pedal acts dead.  Does anyone have any ideas about this?  I'm tired of the dealership making $1000. wrong guesses.  Blue Driver
shows no codes at present.


  • jimdeerejimdeere Member Posts: 19,476 ✭✭✭
    edited June 30
    A friend had a throttle position sensor go bad on his outback. I believe it’s located near the gas pedal. Similar symptoms.
  • NeoBlackdogNeoBlackdog Member Posts: 12,046 ✭✭✭
    When was the last time you changed the rainbow-flag bumper sticker?  
  • RobOzRobOz Member Posts: 9,024 ✭✭✭
  • RobOzRobOz Member Posts: 9,024 ✭✭✭
  • thunderboltthunderbolt Member Posts: 5,909 ✭✭✭
    Thanks for the advice JimDeere. I considered the throttle position sensor, but I thought that would have tripped a code.  According to my Haynes manual, it's on the side of the throttle body, so at least it's easy to get to.  NeoBlackdog and RobOz
    should remember the sage advice, If you can't say something nice, don't say anything at all. 
  • NeoBlackdogNeoBlackdog Member Posts: 12,046 ✭✭✭
    Just ribbin' ya Tbolt!  Around here the Outbacks are known as LAV's, Lesbian Assault Vehicles.  :o  
  • varianvarian Member Posts: 1,138 ✭✭✭
    could also be low fuel flow/pressure from the fuel pump.  usually a simple test by a knowledgeable mechanic.
  • mogley98mogley98 Member Posts: 17,200 ✭✭✭
    First of all stop going up hills and it will be fine, find a nice level area to live in.
    Second this is weird but internet search indicates possibly a brake light switch?
    Can you stromp on it on level ground and it goes fine? Just hills are the issue? checked fuel filter?
    Why don't we go to school and work on the weekends and take the week off!
  • thunderboltthunderbolt Member Posts: 5,909 ✭✭✭
    Replaced fuel pump earlier this year.  New fuel pump has new filter.  Fuel pressure tested fine. Only happens on steep hills.
    Everywhere else drives fine.  Will be checking JimDeere's theory.  Thanks.
  • dunbarboyzdunbarboyz Member Posts: 703 ✭✭
    A plugged catalytic converter could cause that so could a plugged air filter.

  • thunderboltthunderbolt Member Posts: 5,909 ✭✭✭
    Catalytic converter new.  Air filter good.  All good ideas though.  Thanks.
  • hillbillehillbille Member Posts: 10,677 ✭✭✭
    as Jim said had a throttle sensor go bad on son in laws truck and it would go into "limp" mode and act just like you are stating, that was a chevy though, subaru you are on your own...........
  • bigal125bigal125 Member Posts: 1,132 ✭✭✭
    Only one fuel filter on the Outback? Sure there's not another filter somewhere in-line between the new fuel pump/filter and the engine? Best guess from me ...
    Big Al (assuming from your comment about "Sport Mode" means it is an automatic transmission? What size is the engine and does it have a carburetor  or EFI on the engine?)

  • BarzilliaBarzillia Member Posts: 21,775 ✭✭✭
    Bad gas or bad ignition (not valve) timing.
    "Anger has two children -.hope, and courage." Augustine, Bishop of Hippo

    "Und es wird nicht hineingehen irgend ein Gemeines und das da Greuel tut und Luge,
    sondern die geschrieben sind in dem Lebensbuch des Lammes."
  • dunbarboyzdunbarboyz Member Posts: 703 ✭✭
    Is it missing on a cylinder?  And do you have 1 coil for two plugs?

  • thunderboltthunderbolt Member Posts: 5,909 ✭✭✭
    2006 Subaru Outback.  2.5 liter boxer engine.  There's only one fuel filter and it is in the fuel tank on the fuel pump. It is new.  There is a separate sending unit also located in fuel tank.  Gas is changed regularly.  I don't run the vehicle dry, usually top off at 1/4 tank.  Doesn't seem to be missing.  On a steep hill, it feels like the gas pedal is dead and the car goes slower and slower, almost to a stop.  One ignition coil for all four plugs.  There are no codes or check engine lights at present.  My last code was for evap system leak.  Changed gas cap for that.  Going to check the throttle position sensor and accelerator pedal sensor when it quits raining.  Dealership changed the catalytic converter months ago, but didn't help.  Knock sensor tested ok.  Fuel injection.
    4 speed automatic transmission with sport mode that allows you to shift it manually.  No leaks, no burned transmission fluid.
    Oil changed every 5000 miles since I owned it.  Bought it used.  This problem has been going on for months, but I'm driving less due to retirement and the recent stay at home order for the covid outbreak.  Last time I had a timing issue with a
    different Subaru, it would shake constantly until it died.  This car zips around great until I go uphill, which I do whenever I go in and out (Tennessee hill, you know!)  It is a puzzler.
  • BobJudyBobJudy Member Posts: 1,611 ✭✭✭
    Could it be a compression problem? Worn rings or valves at 170k could be a problem. Bob
  • Flying Clay DiskFlying Clay Disk Member Posts: 34,091 ✭✭✭✭
    This is a really weird problem!  I've been racking my brain for the past couple days trying to think up what the problem might be, and I'm kind of familiar with weird * problems on Subaru's too.
    Question...Does the car exhibit the same problems in sport mode as in regular auto mode?
    The only thing I can think of is some kind of an electrical short maybe?  Maybe have a skinned or chewed wire somewhere in the ignition system which a hill causes to short out (i.e. gravity / angle)? 
    Best I got.
    I had a super weird issue on a skidsteer once which turned out to be a timing advance issue.  Took me months to figure it out, but hills weren't involved only engine temps.  Actually, I didn't figure it out, an old wizard did, you know, one of those old geezers who sits there quietly while everyone else is talking, and then when everyone's done he sticks up his finger and says..."You know...I remember this one time a long time ago we had a machine do this...and the timing chain had skipped a tooth...so it would run good until it warmed up and the timing advance retarded and it ran like crap then".  EUREKA!!!!
  • NeoBlackdogNeoBlackdog Member Posts: 12,046 ✭✭✭
    I did a little research on this and on one forum a fella described similar symptoms.  He finally got it fixed by getting the exhaust pipes cleaned out.  His cat had gone bad and pieces of it went into the exhaust system.  When he'd go uphill these would fall back into a constriction somewhere in the exhaust system and plug it up.  Even though your cat is new, the old one may have left enough debris in the exhaust system to be causing the issue.  You might try pulling the muffler and seeing if it's got debris built up in it or just ahead of it.  
    Hope you find a fix!
  • asopasop Member Posts: 7,025 ✭✭✭
    With all these possibilities maybe consider taking it into a mechanic?
  • bpostbpost Member Posts: 30,645 ✭✭✭
    It sounds like it is choking for air or getting too much.  Maybe a restriction in the exhaust or intake, maybe a leak in the intake itself?  How about the computer itself not giving proper fuel when going up hill?
  • dunbarboyzdunbarboyz Member Posts: 703 ✭✭
    I'm stumped! Like Neo would take the converter off and run it up a hill.
  • JunkballerJunkballer Member Posts: 7,838 ✭✭✭
    edited July 2
    If it's running smooth on flat ground and at idle after all of the parts you replaced and you still have trouble pulling up grades, you Sir have a timing issue (check your vacuum lines also), very easy and cheap fix which is normally the way things turn out after tons of money are spent  needlessly. ;)
  • notnownotnow Member Posts: 1,353 ✭✭✭
    My witch doctor senses are leaning toward O2 sensors. 
  • drobsdrobs Member Posts: 21,716 ✭✭✭
    How's the head gasket? It is a Subaru after all.
  • Flying Clay DiskFlying Clay Disk Member Posts: 34,091 ✭✭✭✭
    edited July 2
    Do you have a hitch on the Subie?  If so, you might try hooking a trailer to it and see if it exhibits the same problem (i.e. under a load, but not on a hill).  This would rule out an incline having anything to do with the problem.  Maybe it's just a load (and not a hill) which causes it to bog down.  Just a thought.
    ETA - The hill part of this issue is the most puzzling.
  • Chief ShawayChief Shaway Member, Moderator Posts: 5,817 ******
    As stated above, O2 or mass air flow sensor. 
  • hoosierhoosier Member Posts: 1,048 ✭✭✭
    edited July 2
    Same Problem with a  1998 Honda  CRV.  Not  throwing  any  codes.
     Turns out to be  the  catalytic converter was wore out, it was  changed out  years ago and  the  sensor was rewired. (so no codes)
     Took $200. to local  Muffler shop , now no  Converter and  runs like a  great up hills.  New life to the old girl  at 264,00 miles.
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