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03 Forester hesitating and losing power

Discussion in 'Other Vehicle Discussions' started by invisibledemon, Mar 29, 2015.

  1. invisibledemon

    invisibledemon Bored Moderator VIP

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    So, my forester is giving me issues. above 3k+/- rpm it hesitates and loses power, makes passing a bitch.
    my first instinct is telling me that the A/F sensor is bad, when I first bought the car years ago this was the issue, and it only affected above 3k rpm but if i remember correctly it produced more of a bucking than just a hesitation. also, it gave a CEL.

    I have no CEL and no pending codes at the moment. And I dont want to drop $100 on a sensor if im not positive it will fix it, funds are tight at the moment. If it only gave me a light i could figure it out but no such luck. I have attached some screen shots from my torque app showing the readout of the o2 and the A/F sensors. I believe they are fine and did a comparison with a 03 outback 4cyl tonight to see what his showed and the readout was pretty much the same (he doesnt have any issues).

    Another symptom is that the problem is more prominent when the engine was to op temperature and it gets even worse if the outside temp is above 70-75 degrees.

    I let the car get to operating temp and unplugged the rear o2 sensor first and no change at all, of course it gave me a CEL after that but I knew the problem. Then, I hooked it back up and unhooked the A/F sensor after warm up and zero change as well. hooked it back up and still at square one.

    Looking online and I get a huge variety of results. from the o2/AF sensor, to throttle body. to needs tune up (it could use one, but I checked the plugs and they arent terrible enough to cause issues), to knock sensor, to clogged cat, etc, etc, etc,etc.

    I have to start ripping into the wifes civic this week and replace the headgasket so I cant afford to have both vehicles down. Any suggestions?

    All screenshots were taken while driving and accelerating and hesitating. the ones where the o2 and AF are flat lined are while the car is coasting in gear with neither the brake nor accelerator pressed. Screenshot_2015-03-16-18-13-05.png Screenshot_2015-03-16-18-13-19.png Screenshot_2015-03-16-18-13-39.png Screenshot_2015-03-16-18-14-01.png Screenshot_2015-03-16-18-14-13.png Screenshot_2015-03-16-18-14-24.png Screenshot_2015-03-16-18-14-34.png Screenshot_2015-03-16-18-14-50.png Screenshot_2015-03-16-18-14-59.png Screenshot_2015-03-16-18-19-20.png Screenshot_2015-03-16-18-19-33.png Screenshot_2015-03-16-18-19-51.png Screenshot_2015-03-16-18-19-56.png Screenshot_2015-03-16-18-20-03.png Screenshot_2015-03-16-18-20-06.png
     
  2. |Chaz|

    |Chaz| Well-Known Member VIP

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    Fuel filter? Air filter? Clogged cat?
     
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  3. invisibledemon

    invisibledemon Bored Moderator VIP

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    Lol. Fuel filter was replaced relatively recently. Air filter is fine. Clogged cat I'm not so sure. No way to visibly inspect on subarus bc of the curvature of the pipes. But, the problem isn't persistent and gets worse at times. It does lose power but my fuel consumption is the same as it has always been, no change there. On cold starts it runs almost smooth until it gets to operating temp then it has slight hesitations, if it's warm outside it gets worse. If it were the cat I wouldn't think the ambient air temp would have much of an affect considering how hot those things get...
     
  4. |Chaz|

    |Chaz| Well-Known Member VIP

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    Has to be a sensor issue of some sort. I bet Wil would know, @civicious
     
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