2002 Subaru Legacy Logo
Anonymous Posted on May 01, 2012

Replaced Fuel filter, Plugs and wires, PCV valve and the Throttle air control valve. Still running rough. Could it be an 02 senor or the catalytic Converter? Car wants to dye out when coming to a stop or while decelerating. But not all the time..... ??? Seems like it's starving for fuel.

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Nick Sutherland

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  • Contributor 7 Answers
  • Posted on Aug 20, 2012
Nick Sutherland
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Joined: Aug 20, 2012
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Hi there, i had a similar problem with my Legacy B4 RSK Blitzen, 2 litre Twin Turbo, Engine EJ208. Car would idle sort of ok when cold, after warming up it would idle erratically (idle hunting) and cut out sometimes. I notices the boost gauge hunting along with the RPM'S .I found it to be 2 faults. 1st fault - If you have an after market air filter and the car hasn't been mapped for the extra airflow past the MAF (Airflow Meter) then it confuses the ecu as its taking in un-metered air. Solution - Re-map car to take extra airflow or as i did, i took out the MAF and cleaned it with a can of Carb&Choke cleaner. It worked but still had rough idle.
2nd fault - Air could be in your cooling system. If there is air in the system then the engine temp sensor is reading hot/cold/hot/cold everytime an air bubble passes by, which will cause running problems. You may hear a gurgling or slushing noise in the car, which is air in the heater matrix. Solution - From cold open the header tank and coolant overflow bottle, un car untill engine warm and hold at 2000-4000 rpm untill you see air bubbles rise in the header tank. Make sure your hot air is turned on in the car and vents open. Do this process for 10-15 mins and when you think all air is out of system then re-fit header tank cap. Have a watering can at hand as you may require to top it up during bleeding. It will overflow but dont worry.


Only real problems Legacy's give are , Air Flow Meters, Knock sensors, and Lambda Sensors (O2 sensor). Hope this helps mate, keep us informed on how you get on.

  • Nick Sutherland
    Nick Sutherland Aug 20, 2012

    There is a master reset on the car, which will give you fault codes and test everything for you without having to go to a garage. Over the pedals, behind the dash there is two green wiring plugs, only two wires in each. If you connect these two together and turn on your ignition, you will hear clicking from the engine bay, the fans will turn on and off and a whole lot of other noises of valves opening and closing. Keep an eye on your check engine light. This will flash in a sequence giving you an error code. it will flash a number of times, stop for a second and flash a couple of more times. this will give you the error code number. ie flash's 5 times = 5, break, then 7 times= 7 , your fault code 57. leave connected for 2 mins or so. then disconnect and start car, this will also reset everything in engine bay too.

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5 Related Answers

lexusman

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  • Posted on Sep 29, 2010

SOURCE: My 1997 Subaru Impreza starts,

fuel pump may be weak, not giving enough pressure

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Anonymous

  • 382 Answers
  • Posted on May 14, 2009

SOURCE: Engine light on/off rough acceleration

I would have the coil tested again. May have a bad ground. Also check all major grounds, body and motor.

Anonymous

  • 6966 Answers
  • Posted on Jun 04, 2008

SOURCE: accelerator problems

Hi,

If you have the turbo charged version, this issue refers to the "turbo dead zone" between 3500-4000 RPM. This refers to the no acceleration between these two RPMs and is caused by the time difference between the time the second turbo kicks in after the first turbo has activated. If you are referring to acceleration loss/delay below 3500 RPM, the issue is "turbo lag" which pertains to the delay in time between the stepping on the gas pedal and the 1st turbo activating.

In some other instances including non-turbo versions, the problem may be due to air leak in the intake manifold and the air cleaner. In the turbo versions, it would include the in/out junction of the blower including the clamps.

Hope this be of initial help/idea. Pls post back how things turned up or should you need additional information.

Good luck and kind regards.

Thank you for using FixYa.

Anonymous

  • 2049 Answers
  • Posted on Mar 03, 2010

SOURCE: check engine lightp0170 fuel trim bank one check

I'm guessing your mixture is too lean and it's possibly running a bit rough and there isn't enough fuel getting to the engine. A rich mixture is too much fuel, but that error is usually related to O2 sensors. It might be the O2, but 'trim malfunction,' you're looking at a vacuum leak. Check the oil separator valve then the throttle body gasket and then the intakes. Most likely a vacuum leak and the throttle body, oil separator and intake are the most likely. Run your hand around the bottom of the throttle body and oil separator, if it's greasy/oily there, there's a leak.

If there is no leak, test the MAF sensors...they might need cleaning, and in a worst case scenario, might need replacing.

Anonymous

  • 1 Answer
  • Posted on Aug 22, 2010

SOURCE: I have a 2002 subaru legacy outback. It's a

It could be the front 02 sensor on the cat. I bought one at Napa for around $75, My 02 Outback with 131k had the same issues and it would come and go. At various speeds it would "hiccup" after pressing on the accelerator and it would bog down. I replaced the plugs, wires, fuel filter, and finally it came down to the front 02 sensor.

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