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Discussion Starter #1 (Edited)
The last two morning when I first start my car to let it warm up, for 1-2 seconds after it starts it feels like its going to die. Almost like it has REALLY heavy weight oil or its only firing on 2-3 cylinders. No CEL. 5w-30 M1 Oil. No knocking, other than the typical initial piston slap. Never had a CEL.


In comparison it feels like a diesel when its freezing out, just for 1-2 seconds.
The RPMS go straight to 1200 and fall almost to 300 or so and then after its fit goes back up and fast idles fine until warm. Does not do it the rest of the day, even when its been sitting for several hours and its cold.

Just filled up with gas, and have a vacuum line that was broke, I temporarily fixed it, but with the wrong size hose. Waiting on OEM parts to arrive from Subaru. Its the vacuum line from the intake pipe to the boost controller (NOT the one from the turbo with the restricter pill)
It seems to run fine under any load any other time.



The vacuum line outlined was cracked badly... But was replaced with a different size hose until I get my parts.
 

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I don't see any question in your post, so are you just telling a story here or do you need help? :confused:

If you need help, a good start would be what mods you have on the car...
 

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Discussion Starter #3
I don't see any question in your post, so are you just telling a story here or do you need help? :confused:

If you need help, a good start would be what mods you have on the car...
Well I'm not sure what exactly is going on with the car. The vacuum line showed up tonight so scratch that being the issue... Just a Perrin Up-Pipe and Sti Catback. Nothing else.... Just wants to die when I start it... RPMS fall and then pick back up.. Lopes real bad as its doing it too.. Only on the first start of the day, in the early AM.....
 

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Any diameter hose in that location would have worked as long as it was sealed properly. Those hoses are all the same.

Maybee check the BVP line. Does the car idle at .5k when warm?
 

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Discussion Starter #6
Any diameter hose in that location would have worked as long as it was sealed properly. Those hoses are all the same.

Maybee check the BVP line. Does the car idle at .5k when warm?
Yea 500 to 600 r's when warm... BVP? Battery and alt. are fine.. The rpm's climb to 1200-1400 and then fall really fast for just a second and then go back into fast idle.. Never really seen anything like it before...
 

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Does not do it the rest of the day, even when its been sitting for several hours and its cold.
When you say this, I suspect that the engine is still slightly warm, even after a few hours. I know my engine will stay warm for a solid 3 hours even when temps are in the 30s. The engine temp sensor might be reading no temp, but my heat will come on far sooner than if the car sits overnight, and temp sensor will also climb faster. So I would say this is a cold start problem.

Was there anything different you did the night before this started to happen? For instance, drove the car really hard and parked it without cooling off, or got fuel somewhere you normally don't, or anything like that? Other than the starting problem, is everything else working normally? What happens if you try and give it some gas right after it settles at the fast idle? Try blipping the throttle right after it settles at the fast idle and tell me what happens. When I say blip, I literally mean just tap your foot on the gas once.

I used to have this exact same problem in a Jeep Cherokee and it was a bad relay, but I wouldn't go so far as to guess that here without more info and time to think about it.
 

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Discussion Starter #8
When you say this, I suspect that the engine is still slightly warm, even after a few hours. I know my engine will stay warm for a solid 3 hours even when temps are in the 30s. The engine temp sensor might be reading no temp, but my heat will come on far sooner than if the car sits overnight, and temp sensor will also climb faster. So I would say this is a cold start problem.

Was there anything different you did the night before this started to happen? For instance, drove the car really hard and parked it without cooling off, or got fuel somewhere you normally don't, or anything like that? Other than the starting problem, is everything else working normally? What happens if you try and give it some gas right after it settles at the fast idle? Try blipping the throttle right after it settles at the fast idle and tell me what happens. When I say blip, I literally mean just tap your foot on the gas once.

I used to have this exact same problem in a Jeep Cherokee and it was a bad relay, but I wouldn't go so far as to guess that here without more info and time to think about it.
Well, I fueled up Tuesday night, drove the dog **** out of it, playing around. But waited on a train for about 10 min. (train is less than a 1/2 mile from my house) so it had plenty of cool down time. When I start it in a bit I will blip the throttle. I called Subaru yesterday as well and one guy said it sounded like a momentary vacuum leak that is sealing itself (heat) after the initial start... We'll see...
 

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Discussion Starter #9
Must have been a vacuum leak.... Went to start it this a.m. and it started absolutely perfect (besides the piston slap and valve tick). R's went up to 2k and came down a bit for the fast idle, i blipped the throttle and it went up about .5k. UGH it sounds so nasty when its cold out :(
 

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Well vacuum leaks can cause different types of idle problems so I'm not surprised if that was the problem. I'm surprised you didn't get a CEL though. And I thought you were still having problems after you put in a new hose? Too lazy to re-read all of the posts again, I stayed up all night last night. :)
 
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