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Old 09-07-2012, 12:29 PM   #13851
jsteg
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I disagree. I've seen similar behavior when the engine is stone cold. I wouldn't worry about it.
I've never had the engine, while cold, start, then drop below 1000 RPM's, then shoot back up to 1800.........

Also never seen any fluctuation in RPM's either.
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Old 09-07-2012, 12:36 PM   #13852
myrt1987
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Damnit. Thats not what I wanted to hear....

was hopin more for a "oh yea its a subaru thing. dont worry" lol

damnit!
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Old 09-07-2012, 12:51 PM   #13853
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Damnit. Thats not what I wanted to hear....

was hopin more for a "oh yea its a subaru thing. dont worry" lol

damnit!
Meh. I've seen this behavior. It doesn't do it every day, but I have seen it from time to time. Clearly the computer is playing with the timing and/or gas mixture when the engine first starts.

There are many variables: gas quality, air temp, humidity, engine temp, and so on. Before you decide to do anything about it, I'd wait a week or so, fill up the tank, and see if it continues.

I predict that you will experience this behavior on some days and not on others. Figuring out which combination of variables causes it will be difficult. So I suggest relaxing, observing the situation over the next week or so, and then deciding if a service call is justified.

Your Impreza gets just about the best gas mileage I've ever seen coming from any 2012 Impreza. Clearly your car is running well. I seriously doubt you have anything to worry about.
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Old 09-07-2012, 01:03 PM   #13854
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Yea i think its probably nothing, but it does it pretty often and i would imagine it will only get worse with winter.

In a seeming unrelated matter, one time the radio completely shut off for about 2 seconds and turned back on like nothing ever happened.

Maybe my car is haunted.
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Old 09-07-2012, 01:09 PM   #13855
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Yea i think its probably nothing, but it does it pretty often and i would imagine it will only get worse with winter.

In a seeming unrelated matter, one time the radio completely shut off for about 2 seconds and turned back on like nothing ever happened.

Maybe my car is haunted.
Both of these issues could be poor grounds. Just keep an eye on it and if problems persist, have it checked out.
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Old 09-07-2012, 01:11 PM   #13856
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Yea i think its probably nothing, but it does it pretty often and i would imagine it will only get worse with winter.

In a seeming unrelated matter, one time the radio completely shut off for about 2 seconds and turned back on like nothing ever happened.

Maybe my car is haunted.
The engine changing RPM while warming up is a PZEV thing, not a Subaru thing. I've had a few PZEV cars and they all did this. My 2012 Impreza normally doesn't vary the engine RPM much when warming up, but it definitely catches my attention when it does.

Last edited by ocellaris; 09-07-2012 at 02:20 PM.
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Old 09-07-2012, 01:13 PM   #13857
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The engine changing RPM while warming up is a PZEV thing, not a Subaru thing. I've had a few PZEV cars and they all did this. My 2012 Impreza normalyl doesn't vary the engine RPM much when warming up, but it definitely catches my attention when it does.
Maybe this is why I haven't noticed it on mine and thought it could be a potential problem...I don't have PZEV
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Old 09-07-2012, 01:15 PM   #13858
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Yep, I do. That sucks. It cant be good for the engine to be riding the throttle coaster when its cold.
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Old 09-07-2012, 01:37 PM   #13859
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^^It's normal for cars to idle high when cold. My Impreza does it. My 2010 VW TDI did it. My 1999 Civic does it. Even old carburated cars idle fast until the engine warms enough to set the choke.

I'm confident that no damage is being done during the fast-idle phase of the warm-up.
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Old 09-07-2012, 01:42 PM   #13860
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Excellent pix. From the angle of the pix, it looks like the hitch doesn't reduce the ground clearance. True?
False. Pretty much any way you look at it. But if it doesn't affect you personally, that's awesome. It does look pretty high and tight, but definitely much lower clearance than without it.
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Old 09-07-2012, 01:51 PM   #13861
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Yea i think its probably nothing, but it does it pretty often and i would imagine it will only get worse with winter.

In a seeming unrelated matter, one time the radio completely shut off for about 2 seconds and turned back on like nothing ever happened.

Maybe my car is haunted.
I've never seen an engine jump back up in rpms after it settles down below 1k.

And you're just talking cold start like first thing in the morning, not cold like winter obviously cause it's the beginning of september?

I think you're def. haunted. I'd check the grounds personally, even if it's causing no damage it can't hurt to poke around and get more familiar with the wiring/fuses and all that great stuff. This vid will help...
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Old 09-07-2012, 02:15 PM   #13862
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Well it will settle down immediately after ignition down to 1000ish, then shoot up. So its not like its warmed up when it starts revving.

I know high rpms are normal for cold start, but its the fluctuation that scares me. The fact that sometimes it sounds like the engines about to just shut off before its given more gas.


...or maybe im just paranoid and being dramatic
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Old 09-07-2012, 02:19 PM   #13863
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Originally Posted by sgoldste01 View Post
I disagree. I've seen similar behavior when the engine is stone cold. I wouldn't worry about it.

we are still talking about the new 2012 imprezas right? i think ive seen mines do similar but generally in the early mornings here in LA (not really cold in the early mornings), i leave for work around 530am, but i just start it and go back in the house to get ready so the car can warm up.

ill take a look next time i start it up and confirm if mines does the same.
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Old 09-07-2012, 02:31 PM   #13864
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Well it will settle down immediately after ignition down to 1000ish, then shoot up. So its not like its warmed up when it starts revving.

I know high rpms are normal for cold start, but its the fluctuation that scares me. The fact that sometimes it sounds like the engines about to just shut off before its given more gas.


...or maybe im just paranoid and being dramatic
what car do you have? year and model? the new 2012 one? im confused, if its the new one it isnt a pezv?
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Old 09-07-2012, 02:37 PM   #13865
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Originally Posted by myrt1987 View Post
Well it will settle down immediately after ignition down to 1000ish, then shoot up. So its not like its warmed up when it starts revving.

I know high rpms are normal for cold start, but its the fluctuation that scares me. The fact that sometimes it sounds like the engines about to just shut off before its given more gas.


...or maybe im just paranoid and being dramatic
is it a CVT? Limited means it has to be CVT right?
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Old 09-07-2012, 02:46 PM   #13866
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During every cold engine start, the rpms fluctuate pretty drastically about 600 rpms or so. Does anyone else encounter this?

After i turn the key, the rpms will peak and settle down a bit, and settle, and settle, until it sounds relatively quiet almost like its about to shut off (around 1000 rpms) then shoot up to about 1800. Then hover around there until warm.

Temps havent been near freezing or anything. Should i look into this further?
Seems normal to me, moreso if you have the AC on.
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Old 09-07-2012, 02:54 PM   #13867
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is it a CVT? Limited means it has to be CVT right?
That's correct, he does have CVT if it's a limited...but what does that have to do with anything?
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Old 09-07-2012, 03:35 PM   #13868
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That's correct, he does have CVT if it's a limited...but what does that have to do with anything?
Agreed, I don't see how the tranny could make a difference. I have a 5MT in my Sport Premium, and my car behaves the same way.

I like the idea that it could be a PZEV-specific behavior. I also agree that having the A/C on could make a difference too. But tranny? Not relevant.
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Old 09-07-2012, 03:39 PM   #13869
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Originally Posted by sgoldste01 View Post
^^It's normal for cars to idle high when cold. My Impreza does it. My 2010 VW TDI did it. My 1999 Civic does it. Even old carburated cars idle fast until the engine warms enough to set the choke.

I'm confident that no damage is being done during the fast-idle phase of the warm-up.
True, however, it seems that it would be more "normal" if it didn't go below 1000 after startup, then shoot back up to almost 2k....that seems odd to me, however, like I said, I don't have PZEV.
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Old 09-07-2012, 03:40 PM   #13870
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My 19mm rear sway will be here next Tuesday, i think it will be installed next Saturday when i change my differential oil. Can't wait!
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Old 09-07-2012, 03:51 PM   #13871
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True, however, it seems that it would be more "normal" if it didn't go below 1000 after startup, then shoot back up to almost 2k....that seems odd to me, however, like I said, I don't have PZEV.
Yeah high rpms is one thing, but this yo-yo deal can't be right.

And as far as cvt vs mt I don't know, maybe things are wired differently in regard to TPS and whatever pzev specific crap is in there.

Just identifying what we're dealing with was the point.
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Old 09-07-2012, 03:55 PM   #13872
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I believe the rpm bounce behavior is probably the computer shooting a quick burst of fuel into the engine, causing a rich exhaust, in order to warm up the cat converters. It might even open the exhaust valves a little early too. The momentary rich afr probably boggs the motor for a sec. I wouldn't worry unless it actually stalls out on you.
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Old 09-07-2012, 03:58 PM   #13873
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I believe the rpm bounce behavior is probably the computer shooting a quick burst of fuel into the engine, causing a rich exhaust, in order to warm up the cat converters. It might even open the exhaust valves a little early too. The momentary rich afr probably boggs the motor for a sec. I wouldn't worry unless it actually stalls out on you.
seems legit
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Old 09-07-2012, 04:03 PM   #13874
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Along these startup lines.. Did anyone else notice super shaky startups for the first couple hundred miles? I was about ready to clean the injectors or something but it smoothed itself out.
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Old 09-07-2012, 04:20 PM   #13875
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Along these startup lines.. Did anyone else notice super shaky startups for the first couple hundred miles? I was about ready to clean the injectors or something but it smoothed itself out.
Normal. It doesn't always go away either. Boxer engines are not quiet or smooth on cold starts. Its been this way since I had a 1993 Legacy through 4 Subarus.
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