[SinisterMoose]

I've scoured the forums, and followed much of the advice given here. It has helped the situation, briefly.
The car is a 2001 Outback Wagon, Automatic, 2.5 SOHC, 147K miles. Routine maintenance items have been addressed. Head Gaskets have been replaced, entire cooling system replaced, new timing belt at 105K.
Symptoms: (What I've done) [result]

1. CEL - Knock Sensor (replaced the knock sensor, reset ECU) [light returned 2 days later]

2. CEL Again - 5 different failed sensors (Ground Cable Mods Added three new heavy duty grounding cables, various chassis connections) [all seemed well for about 24 hours, idle smoothed, started quickly, better power to headlights]

3. Today I drove to work 15 miles, no problems no CEL, plenty of power... However, at lunch it died when I stopped for a light. Took a long crank to start, but started fine. After work, on the trip home, it was way down on power, and several times on the trip it felt like it was going to die while cruising at 55mph. It tried to die at a stop light, and I bumped it into neutral where it continued to idle smoothly. On taking off, it staggered and had nearly no power until 3500RPM, where it sprang back to life and seemed fine. Until I let off the throttle to slow, and it bucked, stumbled and nearly died again. At the last stop before home, it was acting normally for a moment, and then the idle started to surge and the car attempted to lunge shortly before trying to die. I nursed it back home. Keep in mind that the CEL is still not on.

I'm left with the only thing that the ECU wouldn't throw a check engine light for, which is a dying fuel pump? Does this sound logical?

Anything else I need to check?

 

[Euchre]

If you've truly followed the classic issues that can arise with Gen. 2s, the fuel pump O-ring failure should pop into your mind. My neighbor's Gen. 2 just went through a failure much like you describe, and the O-ring was the fix.

 

[SinisterMoose]

If you've truly followed the classic issues that can arise with Gen. 2s, the fuel pump O-ring failure should pop into your mind. My neighbor's Gen. 2 just went through a failure much like you describe, and the O-ring was the fix.

Thanks. I was planning the o-ring, and fuel pump as next on my list.

 

[DavidPeab]

Failing alternator will throw a bunch of odd CEL DTC codes. Some your other symptoms match those associated with a bad alternator. Get it checked.

 

[SinisterMoose]

Failing alternator will throw a bunch of odd CEL DTC codes. Some your other symptoms match those associated with a bad alternator. Get it checked.

Thanks, I had it checked last night, it's all good. The battery is 2 months old, and after the grounding mods, and resetting the ECU, the check engine light didn't come on... until this morning on my way to work.

I'm going to connect my laptop this evening to find out what tripped the CEL.

The downstream O2 sensor was replaced a couple of months ago. I have the upstream Air/Fuel sensor waiting to go in, although I've never received a CEL code that it's bad. I believe it was replaced before.

Now to add even more to the hateful nature of this beast.

Without the CEL on this morning, it was still bogging and stumbling.

As soon as the CEL came on, the bogging and stumbling quit. So, I'm leaning away from the fuel pump/o-ring problem. Again, I haven't had a chance to connect my laptop and pull the code for the CEL, but this makes me think it's a failed sensor. I'll know more later this evening.

I inherited this car from my mother who bought a 2011 Outback, because this one was having so many problems. The dealership offered her $500 for it on trade in, with an identical 2001 sitting on their lot for $8990. She understandably balked, then sent the car to me.

I'm a BMW guy. I have four BMWs, and never really wanted a Subaru but it is really a nice, handy car, provided I can get all the problems lined out. It drives well, and when it works right I'm actually impressed by the power of the 2.5, it's not gonna win any drag races, but that's not really it's purpose. One of my BMWs (a '96 Convertible 328i) had very similar drivability issues and it turned out to be a camshaft position sensor.

Thanks for all the suggestions, and I'll get more information this evening.

Update:
P0442 Evap System (Small Leak) was the reason for the CEL.

This morning on the way to work, it was really bad. I think I'm just going to start throwing sensors at it, until I find the one that fixes it. I'm starting to think it's some kind of timing issue. It'll be fine sitting at a stop light, press the throttle and it takes off well for 100 feet then bogs/looses power. Floor the throttle, and at around 3500RPM it comes back to life like it has no issues.

On the interstate, cruising at 70MPH, it's almost impossible to maintain speed, because it feels like the power just goes away, comes back, and disappears again. When it starts this, I can kick it into passing gear, and the problem disappears above 3500 RPM.

 

[DavidPeab]

Search here for a comprehensive list of what sensors folks have been able to substitute and which one absolutely need to be OEM Subaru. I know at least the forward O2 sensor needs to be OEM. Since you have a laptop USB(?) to OBD II connection you should look into using Free SSM. Search here for that software info as well.

 

[cardoc]

Vacuum leak?

Subarus very rarely have EVAP issues. I mean RARE. The switches don't tend to fail and when a EVAP code pops up, the first place I go is vacuum. And a vacuum leak will cause what you describe.

 

[mrbeal]

Vacuum leak?

Subarus very rarely have EVAP issues. I mean RARE. The switches don't tend to fail and when a EVAP code pops up, the first place I go is vacuum. And a vacuum leak will cause what you describe.

I have the evap code on my '02 2.5 - is there a common vacuum leak area or is it all just trial and error until the spot is found? I've just been living with the CEL for months because the car seems to run fine otherwise. TIA

 

[CSFiend]

I have the evap code on my '02 2.5 - is there a common vacuum leak area or is it all just trial and error until the spot is found? I've just been living with the CEL for months because the car seems to run fine otherwise. TIA

I had an EVAP code because the charcoal canister failed. After fueling up it'd struggle to start and idle for a minute or two, or if I left the car running while fueling it would die.

Problem fixed itself after a few months, but just wanted to pass along that it's not always a leak.

 

[cardoc]

I have the evap code on my '02 2.5 - is there a common vacuum leak area or is it all just trial and error until the spot is found? I've just been living with the CEL for months because the car seems to run fine otherwise. TIA

Vacuum hoses at the fuel rail assembly and at the switch attached to the manifold.

I get ya Fiend. I run into mostly vacuum leaks on EVAP issues or a gas cap seal is shrunk/cracked. I think I've replaced 3 or 4 switches out of 100s of cars.

On point, an EVAP code in conjunction with engine performance is generally vacuum related.

 

[w3yni]

Oddly enough my '01 threw the P1443 and we replaced the solonoid. Code cleared...and hasn't been back. Dealer said the same thing -- "Wow..we really don't do too many of these" and this was a volume dealer with a large service department. On the subject of not likely I have a thread going about a possible cracked head which is also exceedingly rare. Been one of those days!! good luck because 147k isn't a lot of miles for one of those.