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Discussion Starter · #1 ·
Hi. My first post here. My 2007 Outback is having a performance lag when gaining hills and accelerating through higher rpm’s 3000-4000. I’ve taken it to for different shops hunting for a solution. My last mechanic visit thinks it’s fuel and that it’s not actually pinging since that would happen in early rpm’s once you step on it. I don’t get the loss of power or rattle sound until 3-4k rpm’s. I also am having difficulty gaining hills at highway speed and residential street speed.

Things I have checked already:
Air intake filter
MAF (cleaned it)
Premium has 92 octane
Sea Foam
Checked both cats for back pressure

I’m not getting any codes and last had it scanned by my import auto Subaru specialist.

Any clues?
 

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Outback 2011 3.6R Premium (sold Jan 22)
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Sounds like you may benefit from checking live data or logging live data when the problem is occurring.

From what you have described it could be various things including spark plugs, fuel filter/pump, dirty fuel injectors etc.

I am suspecting your ECU might be detecting a false “knock” which would then retard the ignition timing. This will show on live data if it is happening.

One other thing to check is the valve timing. If the timing belt has skipped one tooth on either or both camshafts the vehicle will run OK until you get higher in the RPM range.

Seagrass
 

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Discussion Starter · #3 ·
Sounds like you may benefit from checking live data or logging live data when the problem is occurring.

From what you have described it could be various things including spark plugs, fuel filter/pump, dirty fuel injectors etc.

I am suspecting your ECU might be detecting a false “knock” which would then retard the ignition timing. This will show on live data if it is happening.

One other thing to check is the valve timing. If the timing belt has skipped one tooth on either or both camshafts the vehicle will run OK until you get higher in the RPM range.

Seagrass
Thank you Seagrass!

All of those things make sense. I’ve heard snippets of them in many conversations butlack the understanding at that level of engine function to visualize or articulate. I will share this theory with my mechanic. I appreciate it!

One question I have is how can you capture a scan while driving? Is this something I can rent from an auto parts store?
 

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Outback 2011 3.6R Premium (sold Jan 22)
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You can use an OBD2 scan tool to do this. Some of them use your phone and an app.

Alternately you can use a laptop computer, RomRaider software and a VAG-Com cable that connects your laptop to the vehicle OBD2 port.

Most vehicle workshops will have a diagnostic scan tool that connects to the OBD2 port and can diagnose problems, reset codes and log live data.

Seagrass
 
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2008 JDM Outback 3.0R, 5EAT
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Which engine is this? A friends 2.5 SOHC had the same issues you describe because the substrate had collapsed inside the catalytic converter.


 

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2007 Outback 2.5i
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Short of catalytic converter failure, if it were mine I would disconnect the electrical connector from the MAF and see if the issue is resolved. This is functionally testing whether or not the MAF itself has failed. Seagrass hit on my other question having to do with where are you are at with regard to the spark plug change interval.
 

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01 VDC, 05 R Sedan, 06 BAJA EJ257
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High rpm knock and power loss can be fuel filter restriction or pump, AF sensor is weak and sending inaccurate information, MAF is not reading larger air mass properly, vacuum leak, bad grounding, restricted cat, timing belt stretched/out of time, or fuel injectors.

As mentioned, data from the car would be the key to narrowing down what the issue is. Two shops guessing means you may need to find a 3rd shop that would work to find the issue.
 

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You stated you hear a rattle? Would you be able to record the noise? This could be cat substrate broken loose or even resonator. Is this a 2.5 na, 2.5 turbo, or 3.0 h6? If 3.0 h6 and you're hearing a rattle, it could be the timing Chain stretching, guides worn, or tensioner not holding correct tension.
 

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Discussion Starter · #9 ·
So grateful for all your replies. I have a small clue to add from testing one of the diagnostic tips!!!

I unplugged the MAF and the noise went away but performance bogged at 5k rpm, in 1st gear, up a steep Seattle hill on Orcas Ave near Seward Park. My cruise control light is blinking now. When I nearly stalled at the top of the hill I pulled over to park and plug my MAF sensor back in and test again. The pinging sound came back at 3k-4k rpm.

In regard to the speculation of cat substrate breaking up and rattling...I took my car to the muffler shop that installed my cats, first, as suggested by my mechanic. The cats are still within their 20k mi warranty. They drilled a hole in each to test back pressure and both were within limits. The tech gave my exhaust some punches with his hand to test for a rattle of substrate junk but could not get the noise to audibly appear with his punches.

I guess I should try to rent or borrow someone's computer to log live data next? Or does the MAF troubleshoot test tell us exactly where I need to focus for a solution?

**Just thought I would add these details since others were asking and it may be helpful:
2007 Outback
4 cylinder
2.5 liter
SOHC
120k miles currently on odometer
I got my car the royal treatment at 107k mi. in January of 2021:
- Head gaskets, clutch, timing belt, spark plugs (rated 30k so maybe it's time to replace since they are due in 3000mi?), plug wires and coils.

Those are just the big things which have several little things as a part of them. I can take a picture of the whole work order list and post if needed.

I'll post a picture of her too if that helps!:p She's a good lookin' car!
 

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Discussion Starter · #10 ·
UPDATE

I did one other thing in hopes it might reset my ECU. I had corrosion on my + battery terminal so I cleaned it. I did not disconnect the negative terminal so I'm not sure if anything got reset actually. I took it for a drive and had pinging between 3k-4k rpm.

This thread has a very similar issue with no known solution. Many other's chimed in but no one circled back to confirm what it was or the solution.
Gen 3 - Jerking (misfire?) at 4000 RPM

I'm going to start my car and one by one unplug my spark plug wires to see if there is any change in the idle to try to rule out spark plug problem.
 

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Discussion Starter · #12 ·
You can use an OBD2 scan tool to do this. Some of them use your phone and an app.

Alternately you can use a laptop computer, RomRaider software and a VAG-Com cable that connects your laptop to the vehicle OBD2 port.

Most vehicle workshops will have a diagnostic scan tool that connects to the OBD2 port and can diagnose problems, reset codes and log live data.

Seagrass
I just bought this a second ago and it's going to arrive today so I will report back with live data results. Did I buy a POS? It was only $20 and had a ton of positive reviews.
https://www.amazon.com/dp/B07Z3HB7DR?psc=1&smid=A3RYN903ALGZTW&ref_=chk_typ_imgToDp
 

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'03 outback limited, '01 Outback Limited, '01 Legacy L wagon, '96 Legacy Brighton wagon
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For future reference, never clean the positive battery terminal prior to disconnecting the negative. Negative disconnection comes first followed by positive. When reattaching, positive goes first followed by negative. This prevents arcing.
 

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Discussion Starter · #16 ·
I got a Blue Driver OBD2. I set it up and went for a drive to the mountains. Under Live Data there are several options to tick. I ticked the ones that related to fuel. The app suggests ticking no more than 5 at a time. I was shown several graphs while driving but I don't have the knowledge to interpret them. Is there a specific data category I should tick in order to hone in on why my car still runs like sh!t at higher rpms?
 

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Outback 2011 3.6R Premium (sold Jan 22)
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I got a Blue Driver OBD2. I set it up and went for a drive to the mountains. Under Live Data there are several options to tick. I ticked the ones that related to fuel. The app suggests ticking no more than 5 at a time. I was shown several graphs while driving but I don't have the knowledge to interpret them. Is there a specific data category I should tick in order to hone in on why my car still runs like sh!t at higher rpms?
You need to monitor “knock correction” or “timing correction” or “timing” or similar.

From memory ignition timing should be around 40 to 60 degrees when in higher RPM. If it is below 25 then the engine can not respond. If the knock sensor is telling the ECU there is knocking then the ECU will retard the ignition timing until the knocking has gone.

Seagrass
 
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A friends 2.5 SOHC had the same issues you describe because the substrate had collapsed inside the catalytic converter.
This is a GREAT hint!! A blocked exhaust is not uncommon and will cause the symptoms described by the OP.

It is trivial for a shop to test for exhaust-blockage:
  1. Remove FRONT O2 sensor
  2. Install pressure-transducer inplace of it
  3. Run engine and measure the pressure in the exhaust
 
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