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thunderbolt
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.
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Comments

33 comments

Date Votes
  • jimdeere
    A friend had a throttle position sensor go bad on his outback. I believe it’s located near the gas pedal. Similar symptoms.
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  • NeoBlackdog
    When was the last time you changed the rainbow-flag bumper sticker?  
    9
  • RobOz

    Stuff breaks

    0
  • RobOz


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  • thunderbolt
    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. 
    0
  • NeoBlackdog
    Just ribbin' ya Tbolt!  Around here the Outbacks are known as LAV's, Lesbian Assault Vehicles.  :o  
    6
  • varian
    could also be low fuel flow/pressure from the fuel pump.  usually a simple test by a knowledgeable mechanic.
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  • mogley98
    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?
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  • thunderbolt
    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.
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  • dunbarboyz
    A plugged catalytic converter could cause that so could a plugged air filter.

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  • thunderbolt
    Catalytic converter new.  Air filter good.  All good ideas though.  Thanks.
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  • hillbille
    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...........
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  • bigal125
    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?)

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  • dunbarboyz
    Is it missing on a cylinder?  And do you have 1 coil for two plugs?

    0
  • thunderbolt
    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.
    0
  • BobJudy
    Could it be a compression problem? Worn rings or valves at 170k could be a problem. Bob
    0
  • NeoBlackdog
    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!
    3
  • asop
    With all these possibilities maybe consider taking it into a mechanic?
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  • bpost
    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?
    0
  • dunbarboyz
    I'm stumped! Like Neo would take the converter off and run it up a hill.
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  • Junkballer
    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. ;)
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  • notnow
    My witch doctor senses are leaning toward O2 sensors. 
    3
  • drobs
    How's the head gasket? It is a Subaru after all.
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  • Chief Shaway
    As stated above, O2 or mass air flow sensor. 
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  • hoosier
    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.
    3
  • thunderbolt
    Thanks for all the advice.  I'll keep driving waiting for a code to click on for now.
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  • dunbarboyz
    A mechanic I worked with when I was young told me. "If you can't find it, it will develop".
    0
  • thunderbolt
    After almost a year of trying to diagnose the problem in my spare time, I took the car back to the dealership.  They said my SECOND CATALYTIC CONVERTER needed replacement (blocked).  It seems to me they should have known that after replacing the first one.  Another $1200. and the car is back to running like it should, at least so far.  If I get a few more years out of the Subaru, I suppose the extra expense was worth it.  I'm posting this update so everyone else with this problem will have an additional clue as to what may be wrong.  Thanks for all the advice and especially thanks to those who insisted the catalytic
    converter still had a problem.  May your tires never go flat and your gas tank always be 3/4 full. 
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  • SCOUT5
    I'm a little late to the show.  Having had a stopped up catalytic issue in the past that is one of the things I thought of when I read the thread.   But you wrote you had changed it, having a second one I didn't consider.
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  • Grasshopper
    "LOVE" is a Subaru.
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