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2005 Forester XT
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Discussion Starter #1
Not sure if anyone else has this problem but I've noticed that when accelerating (especially in 2nd and 3rd gear) that my car stutters alot. I always warm up the engine to operating temperature before I drive, and it only seems to happen if the turbo is being used. Anybody have any idea on what may be causing this? It's an 05 XT manual.
 

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The turbo is always being used. When ever the engine is on, the turbo is spinning. I would try resetting the ECU once first. Pull the negative terminal off the battery and step on the brake for about 30 sec. Reconnect the battery and drive around. It won't drive as smoothly at first because it needs to relearn. But try that first.

Do you have any mods?

Eurgiez said:
Not sure if anyone else has this problem but I've noticed that when accelerating (especially in 2nd and 3rd gear) that my car stutters alot. I always warm up the engine to operating temperature before I drive, and it only seems to happen if the turbo is being used. Anybody have any idea on what may be causing this? It's an 05 XT manual.
 

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2005 Forester XT
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Discussion Starter #3
Nope, no mods at all (except removing the snorkus). I'm wonderering if it's maybe because the turbo isnt "warmed up" because if i do a little highway driving (about 15 minutes) then it accelerates normally. But that seems a little wierd because you would think if the engine is at operating temperature, then all other components would be warmed up too (assuming a turbo can "warm up").
 

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2006 '06 FXT
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835 Posts
Eurgiez said:
I always warm up the engine to operating temperature before I drive, and it only seems to happen if the turbo is being used. Anybody have any idea on what may be causing this? It's an 05 XT manual.
You warm it up before you drive? How? Let it idle? By "turbo being used" I assume you mean accelerating hard. I doubt it is the "turbo", more likely gas or plugs. Clogged injectors, or an ignition problem.

Since you say 15 minutes of highway driving clears it up, I would suspect a spark plug problem - and you are burning off deposits that built up in slow driving.
 

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Discussion Starter #5
Yes I warm it up by letting it idle. I dont accelerate hard because if I try, the vehicle stutters obscenely...jerking almost to the point of stalling out. The stutterering gets worse the harder you accelerate, but if you back off the accelerator it goes away. It also seems to occur more violently when going up hills (I'm guessing from the needed increase in acceleration to get UP the hill). FXTIam, if its one of those problems will it be a large, expensive repair?
 

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Sounds like a possible bad coilpack or splugs. Its best to take it in to the dealer since you're still under warranty. What you're describing is NOT normal. Unless you're in totally the wrong gear all the time.
 

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Discussion Starter #7
Thanks, I'm taking it in to the dealer tomorrow, I'll let you all know what they say in case anyone else has a simular problem.
 

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2006 '06 FXT
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ZuMBLe said:
Sounds like a possible bad coilpack or splugs. Its best to take it in to the dealer since you're still under warranty. What you're describing is NOT normal. Unless you're in totally the wrong gear all the time.
+1 I agree with Zumble - take it to the dealer.
 

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I have the same problem, and I'm surprised not many people have responded since the last time I posted, many people said it was normal...

this is what happens:

Start car - warm up for a couple of minutes
Drive car, under medium to heavy throttle, under 4k rpm, the car bucks wildly... light throttle, the car is fine...

My car did this since new... once the car warms up fully, the problem goes away...

This only happens when it's really cold out...
 

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2004 Forester XT MT
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Bring it in!

Eurgiez said:
Yes I warm it up by letting it idle. I dont accelerate hard because if I try, the vehicle stutters obscenely...jerking almost to the point of stalling out. The stutterering gets worse the harder you accelerate, but if you back off the accelerator it goes away. It also seems to occur more violently when going up hills (I'm guessing from the needed increase in acceleration to get UP the hill). FXTIam, if its one of those problems will it be a large, expensive repair?
This is exactly how my FXT felt when I had two broken piston rings. Take your car in ASAP.
 

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2006 FXT
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Northwest Tan said:
This is exactly how my FXT felt when I had two broken piston rings. Take your car in ASAP.
How did they determine it was the rings? The only reason I haven't brought in is because I haven't been able to narrow it down exactly when it happens and the dealer can never replicate it. I feel like I have to be prepared with an exact situation and instructions for the service center so that they can reproduce the problem.
 

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2004 Forester XT MT
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Thumbs Crossed for you.

toddlamp said:
How did they determine it was the rings? The only reason I haven't brought in is because I haven't been able to narrow it down exactly when it happens and the dealer can never replicate it. I feel like I have to be prepared with an exact situation and instructions for the service center so that they can reproduce the problem.
My car hesistated when I tried to accelerate hard with the rev's below 3500. There is a point in the rev range were the ECU doesn't listen/react to knock as much. So if you floor it when the engine is already up in the rev's the hesistation isn't a noticeable.

By the time I took the car in, a lot of oil was blowing by and collecting everywhere. So no test drive was necessary.

If your symptoms are similar to what I experienced, have a mechanic drive the car with you as passenger. Tell him to bring the diagnostic tool, too. (This might require two mechanics; one to read the scanner, one to drive.)
Put the car in third, fourth, or fifth. Let the car slow until the tach is around 2k. Then tell him to floor it. This should reproduce the hesitation.

If they won't do a test drive or you are unable to reproduce the symptoms, ask them to check the compression. They might balk at this since it's a PITA to get at the plugs but try your best to convey your concerns.

Good Luck. I hope it's something less severe.;)
 

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But Northwest Tan.. this happened with you ALL the time right ? Not when the car was just cold ?

I doubt that I have broken piston rings since it happened since new... I do get sporadic oil consumption issues, but seems like it's a normal subaru thing... otherwise the car drives fun, esp. once warmed up... it even puts out over 300whp on the dyno ???
 

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I have a similar problem as well! I DO have a TBE, intake, and Ecutek tune, so that may be the source of my problem. I just assumed it was normal, but I do notice it more in the colder weather, even when the car is warmed up. It tends to be a lot less noticeable at highway speeds. I just can't get anyone else to notice it. I drove an STi the other day with similar mods and it didn't feel like that at all, it felt smooooth. I noticed this problem before the mods, but more so after the exhaust. And no chance the dealer will even look at me....so I guess I'll bring it into the tuner.
 

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2005 Forester XT
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Discussion Starter #17
Alright, i took the vehicle in today and asked them to test drive it stating that the vehicle stutters and jerks when accelerating. I told them that if they couldnt reproduce the effect on flat ground than to try it going up hill as it seems exponentially worse. After about two hours the mechanic returned and said he check all hoses, fluid levels, etc, etc and everything looked perfect. Then he said he check the cars computer (I'm guessing he meant the ECU) and saw there was an update for a solution to a "rough idle" problem (possibly the same one in Peaty's guide?) which he downloaded to the car. Viola, problem gone. I tried as hard as I could to recreate the problem afterward because I was skeptical a rough idle solution would solve it, but it did, the car runs perfect now. Thanks to all you who helped, hope this helps others as well.
 

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2004 Forester XT MT
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twg said:
But Northwest Tan.. this happened with you ALL the time right ? Not when the car was just cold ?

I doubt that I have broken piston rings since it happened since new... I do get sporadic oil consumption issues, but seems like it's a normal subaru thing... otherwise the car drives fun, esp. once warmed up... it even puts out over 300whp on the dyno ???
Yep, it happened hot and cold.
 

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2004 Forester XT MT
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Glad you got it fixed!

Eurgiez said:
...Then he said he check the cars computer (I'm guessing he meant the ECU) and saw there was an update for a solution to a "rough idle" problem (possibly the same one in Peaty's guide?) which he downloaded to the car...
Glad to hear it's was just a reflash. Doesn't it seem odd that a new car would need to update it's ECU? I wonder if there is a TSB regarding this?
 
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