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The Modfather
2019 Impreza 5dr Sport - Manual
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8,071 Posts
Discussion Starter · #1 ·
Got back from a trip very late the other night and drove home from the airport and to work the next day, everything seemed fine. Coming home from work yesterday I was taking off from a stop I noticed my forester being laggy and slow. I look and see I'm only making maybe 1 - 3 lbs boost even with my foot down. Every once in a while when I put my foot down it will climb to 5 or 8 maybe 9 and sometimes even shoot to 11 but won't hold there. For the most part it just goes from the vac side to around 0 -1 ish. I got home and checked for codes. I didn't get any (no cel ) nothing pending either. I took a bright light and inspected for any hoses that were off. Couldn't find any. I removed the intercooler to see if there was possibly a hole in the Samco hose but that was fine too. The wastgate kind of felt like it was binding a little when I tugged on the rod with some pliers. I took off the heat shield on the turbo to look for exhaust leaks and check the action of the wastgate. I think the arm was working OK. I rotated the C-Clip and put some never seize in the area since it looked a little rusty. For good measure I double checked with my Access Port that I was still running the proper map. I cleared the ECU with the AP and put the same map back on over top of itself.

Next I went for a ride and it ran a lot worse then before. The boost seemed to work fine but it was bucking, stuttering and generally running like poop. I almost didn't make it home :icon_mad: Still no CEL's I also checked for codes again.

Next I popped the hood to see if I left a hose clamp undone but could not find anything. I started the car and went for another short drive (at first) then since it seemed fine another much longer drive. Now it seems fine :icon_confused: I let it sit overnight and now I'm about to go for another drive. I'm a little baffled at this point. Could it be the Boost control solenoid?

Something I noticed that I'm unsure about, I checked the Recirc Valve when I had it off. The main opening where the recirc hose goes in was sealing fine. However, where the vac line hooks up, I was able to draw air in with only a little resistance. I was under the impression that diaphragm was sealed. I'm wondering if I have a recirc valve issue? I checked the vacuum with the hose off and plugged. It went from about with the recirc hooked up to 19 15 in/Hg with it removed. Still even if it has a little leak I don't think that would create the boost issue or make it run poorly.

I'm open to suggestions, I may put a request in the wanted section for an OEM BOV to see if anyone has a unit I can get and see if that helps a little.

I'm going to go for a drive now and see if it's still running OK like it was when I parked it yesterday and I'll report back.
 

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The Modfather
2019 Impreza 5dr Sport - Manual
Joined
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8,071 Posts
Discussion Starter · #2 ·
OK just took the car for a Dunkin' Donuts run (figured if the car conked out I'd at least not starve to death) and got gas. It ran just fine, in fact it ran great. Not sure what the deal is at this point.

Maybe it's mad because it knew I was going to park it for a while and start driving the Miata since the weather got nice this week? Who knows.
 

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The Modfather
2019 Impreza 5dr Sport - Manual
Joined
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8,071 Posts
Discussion Starter · #3 ·
I guess everyone is as baffled as I am> :shrug:

The Forester has been sitting in the garage since Saturday. I took it to work today and once again it was just fine. I was kind of holding my breath all the way in but no issues at all. The only other thing I did not mention was when I removed the IC to check all the hoses and surrounding vacuum lines; the metal tubes that sit in front of the IC (the attached ones) were pretty munged up. The munge I suspect was an emulsion of sorts. The lines are part of the PCV system from the heads. I blew them out and there was a fair amount of stuff. When I say emulsion think ranch dressing which is mostly a mixture of oil, water and gum. The clogging was akin to a sort of arterial sclerosis reducing the ID down quite a bit. I'm wondering if that had anything to do with the issues?

In any case it seems back to normal, boost is fine and it's running like a top. I do have new plugs to put in but I'll leaving for vacation tomorrow and won't be back till the following Saturday so it will be a little bit before I get to look at the condition of those.
 

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Premium Member
04 Acura TSX the slick 6 speed
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2,355 Posts
2nd set of plugs right? So you're at 120,000 now?

Sorry to hear you're having problems but glad to hear it's running happy again. I can't comment on the mechanical stuff, but I would wonder if your XT is mad at the Miata. I flipped an old Honda a few weeks ago and in the process my Forester sat lonely for about a week. I was wondering if it would get upset.

Have fun vacating!
 

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The Modfather
2019 Impreza 5dr Sport - Manual
Joined
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8,071 Posts
Discussion Starter · #5 ·
The Forester just turned 100K so I wanted to change the plugs. I have to check but I think I put new ones in earlier than the 60K so it's about time.


I also forgot to mention there was a fair amount of munge in my catch can too but my IC was fairly clean so it (the catch can) is doing it's job still.

I was thinking the same thing about being put on the battery tender and just sitting there all jealous like...
 

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The Modfather
2019 Impreza 5dr Sport - Manual
Joined
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8,071 Posts
Discussion Starter · #6 ·
May have found part of the problem. I got a used recirc valve on flea bay and put that on just now. The diaphram on mine was leaking for sure. I'm took some pics and will post in another thread.
 

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I've been having similar issues for a while. I'm pretty sure its the wastegate actuator on my stock TD04 at this point or else a leak in one of the hoses that control the wastegate/BPV. Maybe even the BPV itself like yours. I feel like a number of people with higher mileage XT's have had issues with the wastegate actuator not working properly and the TD04 not holding boost. I get an odd power "fluctuation" at time, sometimes it feels like the turbo "turns off" from 4-5k then boost again at 5, and sometimes it just doesn't pull hard and stutters lightly off the line, but then the next time I drive it will pull hard and drive perfectly. Been having issues (first noticed the 4-5k power drop) nearly 60,000 miles ago. I've replaced almost everything including the BCS. Going to be replacing my O2 sensor soon.

Also possibly related, I've been having oil residue all over the throttle solenoid thing, IC Ypipe, and in that general area between the TB and turbo. No visible leaks and no actual dripping oil, just a light coating (looks like its been misted almost).
 

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Premium Member
2014 Impreza Ltd CVT
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3,319 Posts
I just had something similar with my 04 XS NA .... Obviously not the recirc valve ( lol ) .... I went away for over 2 weeks and when I returned my car ran fine, but would intermittently not idle.

Shake, low low RPM's all over the place, but if gave it some gas, it was fine, also fine driving.

No CELs, put the OBDII monitor on it, all the sensors looked fine, even the front oxygen sensor. Then I remembered, just before going away, I filled up at a station on the way home from a hockey game. Didn't want to let it sit for a few weeks on a nearly empty tank. And You Guessed it by now ...... I got a tank of BAD GAS !!!!! Haven't had that happen in a long time ......

In any case, glad to see you got your fixed also Peaty ...... kind of a let down when you get home and hop in your ride, only to have it act up on you.
 

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The Modfather
2019 Impreza 5dr Sport - Manual
Joined
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8,071 Posts
Discussion Starter · #13 ·
On another forum someone mentioned that even though they have the same MY Forester they have less miles (a lot less) so they will check in the future. Upon further consideration, age may have bearing on this issue too not just miles. In fact a car that sits may even be more prone to problems. The material in question here is some sort of rubberized fabric. Sitting still may let it harden more quickly, not flexing for some time. In my experience, machines like to be run and the longer they sit the more issues you have. I did notice that the diaphragm's damage was all at the bottom 180° area. The part that faces down. I suspect the oil vapors are what attacked the material. The thing is I have a catch can and my IC was for the most part pretty clean, if you remove your IC and have a fair amount of oil (not uncommon) I'd be very suspicious of the bypass valve leaking.
 
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