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2009 Outback Wagon, 2.5 Liter, Consensual induction, Special Edition, 5 Speed Manual
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Discussion Starter · #1 ·
So I'm kind of at my wits end with this issue. Car has trouble revving above 6k (redlines at 7k+) in neutral. Average MPG went from 24.6-24.3 to 15 flat. Driving on the thruway at 80 MPH (barely gets to 80) and then hit a slight incline and the car has all it can do to not drop below 50-55 MPH, and that's flat out. I've tried feathering the gas pedal and that doesn't seem to help.
Car idles great at roughly 550 RPM.
Starts right up no problem every time.
Upstream cat was replaced about a year ago, I don't know about the downstream cat converter, I can't seem to get either to glow at night (every plugged cat I've ever seen will glow after a few minutes of stationary 3k RPM).
I have temporarily seen P0026 and P0028 and they both cleared themselves out after a 3ish drive cycles. They've only appeared once each and very briefly.
If when I start the car for the first time that day, I immediately start going (10 second warm up, instead of my regular 15-20 minutes (suck my ass Greta I don't like being cold)) the car will go like there's absolutely nothing wrong with it for 1st, 2nd and part of 3rd gear, at which point I have no issues getting the engine to rev to bounce the rev limiter (or valves bottom out, I'm not sure about that, but I've convinced myself it's a limiter to feel better about it).

Oil is clean - coolant is clean - it's not head gasket

When it first started happening I figured I got some bad gas, so I ran the tank out and refilled with 93 octane premium, and it didn't change anything.

So I then replaced all 4 plugs with what the haynes manual recommended, which happened to be the exact thing that was in it (double platinum laser welded whatevers)
Forced idle relearn via disconnect battery -- wasn't a waste of money, but didn't address the issue
Then I replaced the PCV Valve and did idle relearn - waste of money and didn't address the underlying issue
I've removed the air filter and throttle body and cleaned them both up and reinstalled them and idle relearn process. - productive but didn't address the issue.

My next step would be to gut the bullshit cardboard fuel filter in the bottom of the sending unit and install a new one under the hood where Subaru used to let them live.
But my gut is telling me that if there were a fuel pressure issue, it wouldn't go away when it was first started and then suddenly rape performance and there's a good chance I'd be getting a related DTC and it's otherwise a lengthy and involved project.

If anyone has any ideas, suggestions or questions I'd love to hear them as I'm growing more and more frustrated with this Outback and I'm thinking about wrapping it around a tree more and more often. Please help.
 

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2005 Outback VDC limited 3.0r
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Check for vacuum leaks. Also sounds like it's just running full rich all the time, like its stuck in warm up mode. Can you monitor your 02 sensor voltages while driving? Clean the maf sensor as well.
 

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Outback 2011 3.6R Premium
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Your vehicle should be fitted with a "top hat" fuel filter as well as the "sock" filter. The sock filter is on the bottom of the fuel pump and filters out any course contaminants. The "Top Hat" filter is the top section of the fuel pump assembly and is after the pump. The "Top Hat" filter filters out all the fine particles and therefore needs to be replaced as part of routine maintenance (normally around 100,000 miles but depends on quality of fuel used and where fuel is sourced from).

Your symptoms could be caused by a fuel flow problem so replacement of the "Top Hat" fuel filter may offer a solution.

By the way, the rev limiter (I do suspect that is what you are "hitting") is there to prevent "catastrophic failure" of your engine BUT the more times you use it the closer your engine is getting to the end of its useful life. Enjoy the ride ;-)

Seagrass
 
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2009 Outback Wagon, 2.5 Liter, Consensual induction, Special Edition, 5 Speed Manual
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Discussion Starter · #4 ·
Your vehicle should be fitted with a "top hat" fuel filter as well as the "sock" filter. The sock filter is on the bottom of the fuel pump and filters out any course contaminants. The "Top Hat" filter is the top section of the fuel pump assembly and is after the pump. The "Top Hat" filter filters out all the fine particles and therefore needs to be replaced as part of routine maintenance (normally around 100,000 miles but depends on quality of fuel used and where fuel is sourced from).

Your symptoms could be caused by a fuel flow problem so replacement of the "Top Hat" fuel filter may offer a solution.

By the way, the rev limiter (I do suspect that is what you are "hitting") is there to prevent "catastrophic failure" of your engine BUT the more times you use it the closer your engine is getting to the end of its useful life. Enjoy the ride ;-)

Seagrass
So that's the filter I was thinking of gutting and installing a universal aftermarket inline filter under the hood, I haven't had it apart yet and the videos I've watched and diagrams I've researched made it look like it was the bottom of the sending unit not the top. If it were plugged wouldn't I get a DTC for low fuel pressure? My OBDII computer says the lowest my long term fuel trim can go is to -3% which makes me think that it's not the problem, but maybe 3% is way out of acceptable range, it doesn't seem like much though.

Check for vacuum leaks. Also sounds like it's just running full rich all the time, like its stuck in warm up mode. Can you monitor your 02 sensor voltages while driving? Clean the maf sensor as well.
I can monitor both o2 sensors with my OBDII scanner, what would I be looking for? and is there something I can test with it or with a multimeter? or maybe a sensor to unplug to force the car into some preset A/F mix?
 

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. . . Car has trouble revving above 6k (redlines at 7k+) in neutral. . . Driving on the thruway at 80 MPH (barely gets to 80) and then hit a slight incline and the car has all it can do to not drop below 50-55 MPH, and that's flat out.. . . Car idles great at roughly 550 RPM.
Starts right up no problem every time.
Upstream cat was replaced about a year ago, I don't know about the downstream cat converter,
. . .
If when I start the car for the first time that day, I immediately start going (10 second warm up, instead of my regular 15-20 minutes (suck my ass Greta I don't like being cold)) the car will go like there's absolutely nothing wrong with it for 1st, 2nd and part of 3rd gear, at which point I have no issues getting the engine to rev to bounce the rev limiter . . .
These symptoms suggest a restricted cat. There was similar case here some time back where the cat was fine when cold, but restricted when warmed up. See: 07 no power limp mode no CELs
In that case, it was the rear cat that had the problem.
 

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2009 Outback Wagon, 2.5 Liter, Consensual induction, Special Edition, 5 Speed Manual
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Discussion Starter · #6 ·
15 seconds after starting it, it kills power (struggling to understand how the cat could warm that fast), i have a few figures from my odbii scanner, but i'm trying to figure out how to upload them onto my computer and off the scan tool... i notice his fuel tank pressure is MUCH higher than mine, mine will get to .1 psi tops...
also i did notice my long term fuel trim did manage to get to -4.9% during acceleration in 2nd gear
 

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15 seconds after starting it, it kills power (struggling to understand how the cat could warm that fast)
Bendy22 said [italics added]
. . as soon as it starts to warm up, it cuts off flow very quickly. This makes sense from what I was experiencing as the car was first cold started, it would rev pretty freely. Within 30 seconds, it started to show signs of being slower to rev . .
so it doesn't take long.

i have a few figures from my odbii scanner,
MAF g/s, Throttle Plate Position %, RPM, and a push at WOT, as in the linked thread, could be indicative.
 

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2009 Outback Wagon, 2.5 Liter, Consensual induction, Special Edition, 5 Speed Manual
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Discussion Starter · #8 ·
Highest I could get maf g/s was in the 9s...
And now it's starting to clear up almost, like before when it started acting up it was the rest of the trip it would happen, but now it feels like it's surging under steady pedal
I can't seem to find the fuel pressure regulator, the Hanes manual is not as helpful as I would like on that subject
 

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Discussion Starter · #10 ·
9s or 90s?

or if 9s, at what vehicle speed, rpm and throttle plate opening position?


Because it's part of the fuel pump assembly in the tank.
I really hate whichever engineer decided it'd be helpful to put so much **** into the sending unit... I can't figure out how to upload from my odbii computer so i'll snap a few pictures with those variables and how they're behaving under certain conditions
 

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Discussion Starter · #11 ·
480513
480514
480515
480516
480517
480518
 

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Discussion Starter · #12 ·
480519
480521
480520
 

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Here's a chart to compare expected air flow (MAF g/s) and rpm at 100% throttle opening. (The table does not apply at any other throttle position.)



Your first and third photos are at 100% throttle. In both the air flow at 6.9 lb/m is 52 g/s at ~3000 rpm. That's somewhat on the low side. However, the problem with restricted cats often becomes more significant at higher rpms. (In the graphs in the linked thread, we can see that the MAF appears to rise with rpm more or less consistent with the chart at the lower rpms, but deviates -- flattens out-- significantly as the rpm goes above 3500 rpm.)

In a recent WOT log of my 07, at around 3000 it was pumping around 62 g/s, and at 3200 rpm it's around 68 g/s. When the rpm reached 5500, it was around 125 g/s. There was a thread here not too long ago where a member logged at higher rpms and it too exceeded the chart's 80% efficiency airflows. So my tendency is to look for g/s that are at least at the chart's level if not above, especially at the higher rpms.

Again, this is only meant to determine if the exhaust might be restricted; there could be something else that's causing or contributing to the loss of power.
 

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Discussion Starter · #14 ·
Yes. 100% right, my secondary cat was plugged... i unplugged it, problem is gone, and the car is faster than it's ever been, mass torque < 3000 rpm and so much more horsepower >3000 rpm... strange that there's no sensor after the second cat....
 

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Yes. 100% right, my secondary cat was plugged... i unplugged it, problem is gone, and the car is faster than it's ever been, mass torque < 3000 rpm and so much more horsepower >3000 rpm... strange that there's no sensor after the second cat....
Okaaaay!

I suspect that if the engine were run WOT at higher rpms we would have seen the MAF g/s rate stop increasing as the engine rpm was still going up. A bad rear cat was exactly what Bendy22 had in the linked thread and that too was heat-sensitive. Here's a graph from that thread showing the flattening in the MAF response:



IF there was a third sensor after the second cat, depending on how it's used by the ECM, it might or might not have led to any other apparent issues or codes leading to a faster diagnosis.

Next step? Replace the intermediate pipe?
 
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