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Old 05-15-2015, 11:33 AM   #1
addisonbassist
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Default 2015 Impreza cold start issue... almost stalling?

Hello, everyone... I've been a Subie owner for quite a while now. I've owned two Foresters and my wife has had an Outback and currently has a Forester.

My last vehicle was something else and it wasn't a great experience... so I got an Impreza 2.0i Sport Premium recently to get back to the world I love again.

The car only has 600 miles on it and I started having a weird issue... in fact, I'm not entirely sure it's an issue at all... but it's definitely a behavior that I have not seen on any of my other Subies.

First of all, the car has NO mods of any kind. This happens with the stereo or air conditioning turned on or off. I have only filled with 91 "premium" gas, and I have used gas from two completely different stations to double check.

Anyway, this issue only occurs from a completely cold start... the car must be sitting for at least 5 hours or so.

I'll turn the key to "on" until the everything is ready and the lights go out and turn the ignition... once the car fires up, RPMs rev way up to 2500 or so and then, suddenly, the car acts like it's about to stall... RPMs will immediately drop down to 500 or even a little lower. The car will then shudder a bit and I can sometimes hear a ratcheting or knocking sound... and then right before it seems like it's going to die, the computer kicks in and RPMS rev way back up to 2500... then slowly drop from there as it warms up.

The whole thing happens in about 3 seconds.

It has never actually stalled... yet. But I just got this thing and worry about how it might act when it starts to get really cold again. I live in North Dakota, so it gets bad up here.

I've done lots of searches online for this and other people have had similar issues. Some have gone nightmarishly wrong, and others were told that it's normal behavior by their dealership... but I wanted to see what you guys think.

Like I said... I have not seen this happen in any of my other Subarus, so the thought of it being normal is a little off-putting to me.

Thanks for your help!
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Old 05-15-2015, 11:34 AM   #2
addisonbassist
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Also...

I do have an appointment to bring the car in for them to look at it on Monday, but I wanted to see what you guys thought first.

Thanks!
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Old 05-15-2015, 12:16 PM   #3
Loyale93
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Take a video. Cold start and going up to 2500 isn't uncommon. A little high, but not crazy.
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Old 05-15-2015, 12:19 PM   #4
addisonbassist
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Quote:
Originally Posted by Loyale93 View Post
Take a video. Cold start and going up to 2500 isn't uncommon. A little high, but not crazy.
The initial rev is not my specific concern... It's what happens immediately after that with the near-stall that's concerning me.
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Old 05-15-2015, 12:40 PM   #5
ShakeAndBake
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about twice in 1 year of ownership, on very cold mornings, my RPMs have bogged for 1-2 seconds on startup. thats it
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Old 05-15-2015, 02:43 PM   #6
addisonbassist
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Default Video...

Here's a video I just put together containing 3 segments...

The first segment is the least bad of the bunch, and the second one has one of the awful noises I've heard. The third video is closer to typical morning startup, although I have seen worse several times.

https://www.youtube.com/watch?v=wlp79-pThLI

This morning was really bad... I thought it was about to finally stall that time. RPM's dropped to close to 500 and the car really shook for a second.

That's another important point... the videos don't capture what I'm feeling sitting in the car when it bogs down, which is a slight rumbling or shaking. Like you'd feel when a car is starting to stall.

Anyway... hope this helps.
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Old 05-18-2015, 02:59 PM   #7
addisonbassist
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Here's a second video I put together...

https://www.youtube.com/watch?v=XcCy0xsJ8iY

I took it in to the shop today... after seeing the videos they agreed that it didn't look right, however, they were going to start a few 2015 Impreza Sport models on the lot to see how they behave.

If anyone has any thoughts on this, I'd love to hear what you think...
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Old 05-19-2015, 10:08 AM   #8
MikeG4936
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This happens to my WRX once every two weeks or so. Not sure why... but then again, that's a completely different engine....

Also, don't put 91 in the car. It does absolutely no good in a NA subaru engine (might actually rob you from a bit of power) - total waste of $$
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Old 05-19-2015, 12:48 PM   #9
addisonbassist
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Quote:
Originally Posted by MikeG4936 View Post
Also, don't put 91 in the car. It does absolutely no good in a NA subaru engine (might actually rob you from a bit of power) - total waste of $$
Interesting... I only use 91 because I thought it runs cleaner and non-91 gas without E85 is really hard to find.

I should avoid E85, though, correct?

Do you think the 91 fuel could actually be the culprit?

I don't remember it doing anything like this when I had the "free tank" immediately after I bought the car... and I'm sure they filled it with the cheapest gas possible.

Thanks for the response!
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Old 05-19-2015, 01:03 PM   #10
OrbitalEllipses
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A mod in here and we still don't notice this is in the incorrect forum?
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Old 05-19-2015, 01:12 PM   #11
addisonbassist
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I didn't post this thread in this forum... looks like it was already moved here by someone else. Not sure when.

No wonder I haven't had any replies... weird.
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Old 05-19-2015, 01:24 PM   #12
OrbitalEllipses
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Ahh. Reported thread to get you moved where you can get some help bud.
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Old 05-19-2015, 01:39 PM   #13
addisonbassist
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Thanks!
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Old 05-20-2015, 11:38 AM   #14
MikeG4936
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Quote:
Originally Posted by addisonbassist View Post
Interesting... I only use 91 because I thought it runs cleaner and non-91 gas without E85 is really hard to find.

I should avoid E85, though, correct?

Do you think the 91 fuel could actually be the culprit?

I don't remember it doing anything like this when I had the "free tank" immediately after I bought the car... and I'm sure they filled it with the cheapest gas possible.

Thanks for the response!
DEFINITELY avoid E85. 91 octane burns slower than 87. It is designed for high compression engines or engines with turbos (prevents per-detonation). Your car was designed, calibrated, and tuned for 87 octane, so just run that.

Doubt it's causing your issue, though. What did the dealership say?
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Old 05-20-2015, 01:01 PM   #15
pagraboski
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Default stalling impreza cold start

Try taking the negative battery cable off for about ten minutes when it is cold, then go ahead and put it back on. Let the car start and run for 3-4 minutes. It may be something to where the MAF sensor isn't calibrated correctly for whatever reason and is causing the stall due to not being able to adjust properly. Surprised you do not have a check engine code or something though. Let me know how it works out.
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Old 05-21-2015, 11:54 AM   #16
SpectreRT
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FA20 platform had a similar issue. Dealer ECU flash resolved it. Any idea if there have been software updates for the NA FB platform?
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Old 06-03-2015, 11:40 AM   #17
addisonbassist
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Sorry for the late reply on this... I'm a working musician with a day job (and family) as well and Summer gig season has started, so I've been pretty busy.

Anyway... dealership said what I thought they might say. "No codes, no problems!"

Seems pretty typical in these days of computer operated vehicles, and it's pretty disappointing... but I can't blame them. They're only allowed to do so much. If the computer says there's nothing wrong, they can't just start poking around.

They did, however, provide me with a service bulletin that talks about different fuels causing strange RPM behaviors (it mainly talks about a "searching" behavior at cold startup) in their PZEV models because of the cars were built to follow CA guidelines and not all states use the same fuel as CA. I'm not sure if it completely describes my "dive-bombing RPM" problem (especially since the gas I was using contained no ethanol), but it says that Summer blends that contain ethanol are the worst offenders and winter blends are better... fuels without ethanol are recommended. I'll try to get the bulletin number and post it here, but Subaru says it's completely "normal" behavior.

The dealership has a 30 day exchange program, so I initiated that exchange since my car seemed to be on the worst end of the behavior range one would expect from the service bulletin. Sales and service both agreed with me on that one. My wife's Forester is PZEV as well, and it gobbles up any gas you give it.

Regardless, service and sales both asked if I'd be willing to put ethanol-free 87 in my tank to see if it would make a difference... a few days later I finally burned through my ethanol-free 91 tank, filled with ethanol-free 87 and lo-and-behold... there was an immediate difference in pretty much EVERYTHING.

Cleaner start, more power AND better mileage. The start is still a little rough... I could still hear strange noises I've never heard before in any other Subie I've had and there is still a bit of an initial shudder... but the immediate dive-bomb in RPM's was pretty much gone. I was both relieved and pissed at the same time... strange mix of emotions.

So, now I have to wonder... did I coincidentally get bad gas from two completely different gas stations (Tesoro and Shell) in completely different parts of town, or does my particular car just hate 91 octane gasoline?

Since my car's manual says its supposed to run fine on 87 octane and above, would you guys consider this as being an issue, or would you just move on? Part of my problem is that ethanol-free 87 octane is fairly hard to find where I live... there are only about 4 or 5 gas stations in town that even carry it.

Should I put 91 in again just to see if it was a case of bad gasoline and not 91 at all?

I just don't feel like any car should be this sensitive to gasoline unless it's a high performance vehicle of some kind, which it is not. It's about as basic as it gets... but, like I said, I'm not a car expert of any kind.

Thanks again for all the help!

Last edited by addisonbassist; 06-03-2015 at 11:49 AM.
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Old 06-04-2015, 02:36 AM   #18
CosmoTheCat
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It's a totally different engine than your prior Subarus. They make different noises, especially on cold start. They've got them trying to heat the cats up and get running clean ASAP now.

Your car could hate 91 octane. e85 is a totally different animal than e5-e10, which is what most of your pump 87 is. I prefer to avoid ethanol for my lawnmower/chainsaw/weedeater, but it's not worth the hassle or expense of going to that one pump in town that has ethanol free 87 for about a buck a gallon more than everywhere else.
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