Engine acceleration stumbling

Tiny
JZONTELLI
  • MEMBER
  • 2000 SUBARU OUTBACK
  • 4 CYL
  • AWD
  • AUTOMATIC
  • 130,000 MILES
Having a problem at take off, from a complete stop. I accelerate and the engine does not have the power it used to. Also, sometime (not always) when maintaining speed say of fifty five mph, the engine will do a stuttering or stumbling, like it is not firing correctly. I put a new fuel filter in but that was not the problem. Any recalls out there? Any ideas? Thanks.
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Tuesday, August 19th, 2008 AT 9:15 AM

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Tiny
JACKSCARS
  • MEMBER
I have a similar problem with my 2001 2.5 lityer at 185,000 miles. Reasonable starting from cold but stumbles badly during warm up and sometimes beyond. It starts and runs well when fully warm. Stumble and bog are very bad and pose a safety problem. Code indicates a misfire on three of the cylinders so I replaced the plugs which were clean but the gaps had opened up. No improvement. Thinking that a build up on the back sides of the intake valve might be acting as a fuel sponge, I dosed the engine with SeaFoam, which I have done many times with all of my vehicles and there was no improvement. The other code that appeared indicated a failed knock sensor. I have not replaced it simply because I do not want to spend the $100.00 or more on a part that cannot be returned. This all feels like a fuel problem, rather than an electrical one as it feels like an overly lean mix during the periods of trouble. I am a bit familiar with soem of the Bosch injection systems and if I knew more about this one I would be looking for a failed warm up pressure regulator, but as I say I just do not know enough about these to make a call. I have been looking for a schematic for the injection system in general but have been unable to find anything useful. If anyone knows about same I would appreciate knowing where it is. Thanks, Jack
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Saturday, September 24th, 2011 AT 11:02 AM
Tiny
RASMATAZ
  • MEMBER
Do you have a check engine light and when was last tune-up performed?

Lack of acceleration, chugging, hesitating, bogging, misfiring etc, could be caused by one of the following below:

Oxygen sensor.

Catalytic converter.

Fuel injectors dirty/sticking.

Mass airflow sensor/Airflow meter.

Throttle position sensor.

Crankshaft position sensor.

Knock sensor.

Manifold absolute pressure sensor.

EGR valve.

Fuel pressure regulator leaking or defective fuel pump.

Fuel contamination.

Foul/defective spark plugs.

Open spark plug wires.

Ignition coil/Coil packs defective.

Incorrect ignition timing.

Cap and rotor.
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Saturday, December 10th, 2011 AT 10:01 AM

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