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Old 06-18-2017, 06:12 PM   #1
bascotie
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Default Another idle / turn off issue when slowing down to a stop

Hi guys,

I've read about this online quite a bit, but still haven't narrowed it down.

I have a :

2014 Subaru WRX 5 door

After somewhere in the 10k-15k mile range (possibly after the first time replacing the air filter), I would notice on some drives, when coming to a stop, the idle would dip abnormally low, and often times it would shut off completely. Sometimes it'll dip low enough where the dash lights come on, but then it saves itself.

I've tried:

- Cleaning the MAF
- Replaced the air filter again (during another normally scheduled maintenance)
- Reset ECU recently and turned key to on for 20 seconds, turned to off, then cranked it up fully and let it idle for 25 minutes.
- One thing that seemed to work for 3-6 months was having a family mechanic clean out the throttle body (they sprayed gasoline or something up through the intake for a while). After that, it wasn't 100% idle, but it didn't turn off for months.

Here's some video to see/hear what it sounds like when the RPM dips.

In this first video, you get a dip around around 1:53

Dip at 1:53

Here's another vid after letting it finish idling for about 20 minutes, I then filmed the RPM's from the dash and blipped it a couple times which resulted in a dip (not as bad as usual, but still not proper)

One drip around 0:45s
Again around :59s

Dip around :45 and :59 at least

UPDATE:

The videos are currently taken down, but I do have an update to the situation.

I recently got check engine code P0171, checked it with a scanner, and it was "System too lean"

This happened right after filling up fuel, so I re tightened my gas cap, waited a day, and it disappeared, then came back, and eventually disappeared again.

I figured this would be a good time to take it back to Subaru. They had it for about a week, said they weren't able to reproduce the problem . They did a leak down test and found no issues, then they did an idle reset (not sure what more they included in the idle reset than what I did by resetting the ECU and letting it sit for 20-30 minutes.

So far, though, the idle feels a lot more sturdy, no turn offs, etc. It's been a few days now so I'm keeping my fingers crossed in hopes that it actually took care of it. Anyone know what more they would've done in an idle reset?
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Last edited by bascotie; 08-27-2017 at 02:17 PM.
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Old 06-19-2017, 01:07 AM   #2
mrsaturn7085
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Are you on a stock tune? Any mods (such as a BOV)?
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Old 06-19-2017, 01:26 AM   #3
bascotie
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Quote:
Originally Posted by mrsaturn7085 View Post
Are you on a stock tune? Any mods (such as a BOV)?
Thanks for the reply.

The car is totally stock (unless you count the short shifter that came with it)
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Old 06-19-2017, 05:43 AM   #4
Max Capacity
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Are you sure the air filter box went back together correctly ? On a Legacy GT it's hard to get the bottom of the box into the correct position so the box is sealed and doesn't leak air.
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Old 06-19-2017, 12:39 PM   #5
mrsaturn7085
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A leaking airbox should still pass through the MAF and not cause stalling issues.

My guess is you have a very small air leak, post-MAF. Try spraying a small amount of starting fluid near the injectors and compressor inlet and see if the idle speed jumps up a bit.

Factory maps can benefit from a little more idle error timing compensation, but the factory maps are not bad enough to cause stalling.
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Old 06-19-2017, 04:37 PM   #6
bascotie
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Quote:
Originally Posted by mrsaturn7085 View Post
A leaking airbox should still pass through the MAF and not cause stalling issues.

My guess is you have a very small air leak, post-MAF. Try spraying a small amount of starting fluid near the injectors and compressor inlet and see if the idle speed jumps up a bit.

Factory maps can benefit from a little more idle error timing compensation, but the factory maps are not bad enough to cause stalling.
Thanks for the reply everyone.

I'm planning to get another cleaning done on the throttle plate/body hopefully sooner rather than later.

As far the starter fluid test (excuse me, I don't normally do too much mechanical work myself), are you saying to just spray some starter fluid into the turbo inlet while it's idling to see if the idle jumps up?

Would I have to do this at the exact moment that the idle is dropping? It doesn't do it constantly so it'd be a bit tough to time it just right and , even then, not sure if I'd be able to tell if the fluid did it or the car just pushed it back up itself.

In any case, assuming it did, what would be the next step? Thanks for your help and excuse my mechanical ignorance.
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Old 06-19-2017, 07:10 PM   #7
mrsaturn7085
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You spray the fluid externally (just a little) and if there is a leak, the vacuum will pull the starting fluid (ether) into the inlet and cause the RPM to rise.
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Old 08-27-2017, 02:17 PM   #8
bascotie
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Posted an updated in the original post.
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Old 12-11-2017, 12:57 PM   #9
jrr363
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Did you ever get this permanently fixed? My 2014 wrx is doing the same thing. Driving me absolutely crazy. It has 19K miles on it.
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Old 12-11-2017, 11:51 PM   #10
bascotie
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Quote:
Originally Posted by jrr363 View Post
Did you ever get this permanently fixed? My 2014 wrx is doing the same thing. Driving me absolutely crazy. It has 19K miles on it.

Hi,

A few months ago, I took it back to the dealer concerning the check engine code I was getting (something about a vacuum leak I believe).

They could not find the problem, though they said they reset the idle, dadada, and I actually did not have the problem for a long time after that.

A few months later, it happened after I filled up gas. I got another code but this time it was for a "large" vacuum leak.

It would run really odd and almost turn off when idling. I decided to to push down on the gas cap and then turn it (more than a few times) whenever I closed it up. I've been doing that and so far it's been so good. I'll try an update this should it come back.

It's probably been 2+ months since I started doing that.
I have not replaced the gas cap yet, just have been pushing it in as I turn it (in the hopes that it'll seal up better)
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Old 12-12-2017, 10:53 AM   #11
jrr363
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Thank you for the reply Bascotie. I tried the gas cap trick and nothing... I am not getting any engine codes. I have reset the ECU and "Idle reset" 3 times. I am taking it to the dealer for the second time.

I am going to have them do/check vacuum test, O2 Censors , and maybe throttle body cleaning? Should I ask for them to check anything else? I say this because the subaru dealer where I live is tiny and only has two mechanics.

Could you look at this video and tell me if this is what yours was doing?
https://www.dropbox.com/s/7a0ydvces3...%20PM.mov?dl=0
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Old 12-12-2017, 12:56 PM   #12
Charlie-III
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Evap leaks are most common when either you don't get the gas cap tight or the cap seal is failing.
Check the top of the filler tube for rust, clean if need be.
A swipe of wheel bearing grease on the top of the filler neck may fix the issue short term.
After that, there are a couple valves (one under the hood, one by the charcoal canister) that may be failing or, the filler tube has rusted through (likely large leak).

Last edited by Charlie-III; 12-22-2017 at 11:35 AM. Reason: Fix typo.
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Old 12-12-2017, 02:04 PM   #13
jrr363
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Thank you Charlie. I am at the dealer right now. The vehicle has never been up north and never driven in the snow so I highly doubt the rust theory. The gas cap will raddle when I shake it though? I swear if itís a faulty gas cap I am going to start going to church... because thatís just bad luck.

I told the dealer that after hours of research it has to a vacuum leak, MAF, IACV, or maybe throttle body is dirty?

I have only owned the vehicle for one week and now
Iím scared to drive the thing.

If anyone else has any ideas please help me!
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Old 12-12-2017, 03:59 PM   #14
bascotie
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Quote:
Originally Posted by jrr363 View Post
Thank you Charlie. I am at the dealer right now. The vehicle has never been up north and never driven in the snow so I highly doubt the rust theory. The gas cap will raddle when I shake it though? I swear if itís a faulty gas cap I am going to start going to church... because thatís just bad luck.

I told the dealer that after hours of research it has to a vacuum leak, MAF, IACV, or maybe throttle body is dirty?

I have only owned the vehicle for one week and now
Iím scared to drive the thing.

If anyone else has any ideas please help me!
Hi Jrr,

In my case, I've taken it to the dealer 2-3 times. The last time they did a full leakdown test and found nothing.

I've tried cleaning the MAF (the problem did seem to occur right around the time I replaced an air filter, but I've had it replaced again since then with no improvement until recently).

I did have a similar issue to yours, it would drop too low when I would come to a stop and sometimes shut off completely, or recover itself last moment.

If you find out what fixes yours, please let me know so I can keep it in mind in case it happens again
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Old 12-12-2017, 06:34 PM   #15
jrr363
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After 4 hours they found a vacuum leak but the problem remains. Going to autozone and buying a new gas cap and battery to see if that fixes the problem.
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Old 12-13-2017, 11:53 AM   #16
jrr363
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Quote:
Originally Posted by jrr363 View Post
After 4 hours they found a vacuum leak but the problem remains. Going to autozone and buying a new gas cap and battery to see if that fixes the problem.


The Memphis Subaru dealer refused to work on it anymore. Car has stalled 4 times in the past 20 miles.

I am getting the dealer I bought it from to buy it back.
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Old 12-13-2017, 03:53 PM   #17
bascotie
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Quote:
Originally Posted by jrr363 View Post
The Memphis Subaru dealer refused to work on it anymore. Car has stalled 4 times in the past 20 miles.

I am getting the dealer I bought it from to buy it back.
You'd think with the amount of people who have had these symptoms, they would have sent a memo out on the proper fix for it
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Old 12-13-2017, 04:08 PM   #18
jrr363
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ĎYou would thinkí! This is ridiculous. The only reason I bought a Subaru was because we are having a baby and I need something safe/with back seats. And it isnít very safe when the engine goes completely out while driving.

Thanks for your replyís Bascotie. I hope someone can figure this BUG out.
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Old 12-13-2017, 05:37 PM   #19
Scorpius
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Check your turbo inlet. The stock units are notorious for tearing.
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Old 12-22-2017, 10:50 AM   #20
jrr363
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bascotie,

After I sold the 2014 WRX back to the dealer I bought it from, they said it was the throttle body and a intermitted vacuum leak.. Please take yours to a Subaru deal that knows what they are doing and get them to check the throttle body. I took it to my local Subaru dealer 3 times and they couldn't figure it out. They had the car in the shop for 10 working hours and in the end turned me away.
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Old 12-22-2017, 06:54 PM   #21
danger1138
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Default Another idle / turn off issue when slowing down to a stop

Is the car stock or somewhat modified?
If stock & under warranty by all means have the dealer work on it.

If modified, this issue is usually fixed in the tune. It may be the long or short term fuel trims effing with your idle.
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Old 12-22-2017, 07:34 PM   #22
bascotie
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Quote:
Originally Posted by jrr363 View Post
bascotie,

After I sold the 2014 WRX back to the dealer I bought it from, they said it was the throttle body and a intermitted vacuum leak.. Please take yours to a Subaru deal that knows what they are doing and get them to check the throttle body. I took it to my local Subaru dealer 3 times and they couldn't figure it out. They had the car in the shop for 10 working hours and in the end turned me away.
From all the reading I've done on the issue, that was one of the possibilities I found. I took it to a family mechanic a year or two ago, they cleaned out the throttle body, and it wasn't 100% but it did not turn off for at least a few months after that.

Eventually, the problem came back.

The good news is, since I last took it to the dealer and they told me they didn't know what it was (and just reset the idle, did a leakdown test, etc) the problem has pretty much been gone.

I had one small issue shortly after filling up gas where the car was running real funny ,and as I mentioned before, I was getting a CEL code about a large leak. I retightened the gas cap and have been carefully to kind of push it in and tighten after each fill up, and so far the car has been running fine.
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