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Smooshed FOTY 2011
2005 Lifted 2.5 XT 5-Speed MT Dual-Range
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5,732 Posts
Discussion Starter #1
Well, here it goes. My car hasn't felt "right" for the past couple thousand miles or so. It feels just ever so slightly down on power, and when idling, I sometimes get what feels like a miss or a jutter.

But when accelerating, it feels like something is just hold it back from working 100%. When the boots is supposed to kick in, it feels like it wants to go, but only at about 80-90%.....and between 4000-5000 RPM, what once was brutal acceleration now feels very tame and uneventful. It's extremely difficult to describe, but that's about as good as I can describe it. But here is the odd thing. A couple thousand miles ago, when this first happened, I took out the MAF sensor and sprayed it with MAF cleaner. It ran PERFECT for a couple of days, then it started to bog down again. So I cleaned it again, and again to the point where now it doesn't matter if I clean it or not, it still feels bogged down. --BUT-- it has always been intermittent. I would say 80% of the time it runs like it's bogged down, but every so often I'll get a whiff of it running perfectly, and you can instantly feel it, even when you're just putting around town. It feels much more responsive and powerful (like it's supposed to), but then a few minutes later, it bogs itself back down to 80-90% of what it should. That's why I was thinking it was a sensor or the MAF...

So, I replaced the MAF (which isn't cheap BTW), popped it in and nothing changed. I don't get as much vibration/missing at stop lights anymore, but I still get the same bogged down acceleration "feel" as I did before. And the whole thing is still intermittent, and sometimes I'll still feel it snap out of whatever problem it has, run fine for a couple of miles, then bog right back down again. And like I said before, it's not a huge bog, but for someone who has been driving the car for the past 30,000 miles, I can certainly notice it when it is/isn't running right.

Now to be honest, I'm completely out of ideas, and extremely frustrated. Does anyone have any tips or hints and to how I can find out really! is causing this? This has been plaguing me for the past few months and I'm almost about to go nuts with it.

Any suggestions will be highly appreciated.

Thanks, Josh.
 

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Smooshed FOTY 2011
2005 Lifted 2.5 XT 5-Speed MT Dual-Range
Joined
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5,732 Posts
Discussion Starter #2
Update: Just took out the car for some late night time driving as it's quiet and I can concentrate more on what the car is doing. First, there is a noticeable, but slight stuttering right at the 2750 RPM mark when in 4th gear going up a hill or holding speed on the highway Not sure if this is a separate issue, but it is noticeable. (and this too has been happening for a while as well, but seems like it's getting worse as it used to only occur every so often, but now I can replicate it)

Also, when doing WOT zero to highway speed runs, it feels as though there is a dead spot around 3800-4900 RPM. It pulls, then feels like it doesn't pull as hard (or VERY slight stutters/missing), then pulls again. It's not as consistent or smooth as it used to be. But the problem area seems right around those RPM's. My 0-60 times (I did many) are all constantly around the 7.8 - 8.0....which seems about 1 to 1.5 seconds off what I normally used to get.

Don't know if this helps, just rambling on I suppose, but hopefully someone could shed some light if they've had similar issues.
 

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8,844 Posts
Mine was doing something similar. From 4-5k rpm it felt like it went to 0 boost, then at 5k rpm it was like it suddenly hit boost again.

I'm now in the process of replacing a number of parts. The main things I've found are that a pcv hose was torn (between the intake manifold and pcv valve), and the turbo had a ton of shaft play. Also the injectors were pretty dirty. Injectors are now out for a rebuild and the turbo is going out soon as well.

See if you're losing boost when you notice the issue. If you can log that would be even better. It could be pulling timing due to poor quality gas, or the wastegate isn't holding pressure etc. Could really be just about anything (I spent about 40,000+ miles with the intermitent issue, wasn't bad at first but started becoming more common until I decided to pull it all apart this summer), was almost ready to just give up on the car!

Also check your compression and leak down.
 

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Smooshed FOTY 2011
2005 Lifted 2.5 XT 5-Speed MT Dual-Range
Joined
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5,732 Posts
Discussion Starter #4
Well, my intermittent rough idle is back, so a new MAF did absolutely nothing really. I'm going to check a few things later tonight, how would I go about logging the data?
 

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Registered
2004 Forester 2.5XT 4EAT
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234 Posts
Check your front O2 sensor. You described all my car's problem to a "T" and i switched out my up-stream a/f sensor (O2 sensor) and it fixed it. If it is on its way out it wont necessarily trip a CEL. Just my 2cents.
 

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Smooshed FOTY 2011
2005 Lifted 2.5 XT 5-Speed MT Dual-Range
Joined
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5,732 Posts
Discussion Starter #8
Check your front O2 sensor. You described all my car's problem to a "T" and i switched out my up-stream a/f sensor (O2 sensor) and it fixed it. If it is on its way out it wont necessarily trip a CEL. Just my 2cents.
Dude, I hope you are right. I have a spare one from my engine swap, so I'll swap those out later tonight and see what happens. I was so peeved this morning when it started to rough idle again that I found myself looking up used Jeep Cherokees on AutoTrader today. :icon_frown:

I'll swap out that sensor and go from there, thanks for the encouragement.
 

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1998 Forester S
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890 Posts
Probably too early, but did you swap it out and find out if that was the problem?
 

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Smooshed FOTY 2011
2005 Lifted 2.5 XT 5-Speed MT Dual-Range
Joined
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5,732 Posts
Discussion Starter #11
Probably too early, but did you swap it out and find out if that was the problem?
Not too early at all. Swapping the O2 sensor was a cinch. --BUT-- my spare sensor was garbage. I swapped it in, and the car immediately felt like crap. I believe it was in "low boost mode" or "limp mode" or something. No codes, but it was running like crap. I put my old one back in, and it's back to running the same (as in before I swapped it to begin with).

-- ANOTHER BUT --

While doing the swap, I somehow managed to cut two of the wires on my "better" working O2 sensor, so I just tied the wires together and used some electrical tape. Looks like it's going to be getting a brand new O2 sensor regardless.......but i'm hoping it'll fix the issue. I pulled it out and it was all sorts of colors, and had crap all over it, so I'm crossing fingers that I'll be able to pick one up (or have Jackie at Annapolis overnight me one). I have a feeling Jackie could overnight me one for cheaper than the local dealer anyway.

I'll keep everyone posted.
 

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Smooshed FOTY 2011
2005 Lifted 2.5 XT 5-Speed MT Dual-Range
Joined
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5,732 Posts
Discussion Starter #12
It could be a valve clearance issue. The exhaust valves get to tight and this causes mis-fires.
This has also crossed my mind, which is why on Friday it's going in for a compression and leak down test to make sure the internals are up to snuff. The engine only has about 10,000 miles on it since the rebuild, but since then, the timing belt has slipped 3 times, and one of those times it slipped 3 teeth on the crankshaft sprocket. (4 and it would have been toast) So this will pretty much give me peace of mind that the internals are good.
 

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2006 X
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36 Posts
Intermittant issues are hard to diag.
Does it blow smoke at all? Make a better note of when it comes good (when cold, any gear, any acceleration) Check for boost leaks as someone said. Have the car running and listen for air hissing, try revving it and running your hands over piping (might be hot) feeling for air blowing. Might be fuel filter blocking up and starving engine occasionally fuel gets through. Could be coil pack on the way out. Exhaust could be bent or cat/muffler crumbling and restricting flow. Turbo could be cooked. Crank angle sensor could be playing up. Without plugging into a scanner or oscilliscope and reading live data it would be hard to guess without throwing things at it.
 

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Smooshed FOTY 2011
2005 Lifted 2.5 XT 5-Speed MT Dual-Range
Joined
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5,732 Posts
Discussion Starter #14
Well, I ordered a new O2 sensor today from Jackie. And like I thought, having her overnight it was about $120 CHEAPER than driving 70 miles to my local POS dealership to buy one. Not to mention, the parts guy there is still a freaking joke. Garcia Subaru in El Paso....WORST dealership ever, they're literally all little pieces of crap walking around in human flesh.

So we'll see if that fixes it (I need to replace it regardless). If not, I managed to find out that the guys that used to be at MCS Motorsports (my local shop that went bust a few months ago) are still at it, and they're going to take a look at it for me this Friday under a scanner to find out really! is going on.
 
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