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Old 06-04-2019, 06:20 PM   #1
adventures91
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Member#: 349672
Join Date: Mar 2013
Chapter/Region: NWIC
Location: Seattle WA
Vehicle:
2003 WRX Wagon
Blue

Default Evap Error p0457 and idle issues

I recently had some work done on my wrx and ever since I have been getting an evap error code of p0457, the car has been stalling when coming to a stop, and has a rough idle when cold starting. I also can no longer fill the fuel tank all the way.

I know this could be any number of things. The car is fairly heavily modified with the most recent modifications being a front mount inter-cooler, delicious tuning e85 kit, 1700cc injectors, all new fuel lines in the engine bay, fuel rails and a purge tank setup with twin fuel pumps.

The car was tuned and had for the most part driven great but I started noticing an occasional hesitation when at part throttle right before boost kicks in.

I started noticing the stalling issue and let my tuner know he said he would look into it, however, I have really not heard anything back.

I know the idle and stalling problem could be due to the tune. Most commonly, I see people saying it is probably an issue with injector scaling.

However, I have noticed one thing with the way the shop has my fuel lines plumbed. The evap line from the tank is no longer hooked up. Also the evap valve and solenoid are attached correctly except for the line that used to go to evap line from the fuel tank which is left open and just in the engine bay.

I have looked at the evap faq's and a few other resources on this site and this seems like a problem.

The first issue I see with this setup is I'm reading that the vapors are pulled out of the tank with engine vacuum. Since the line is no longer hooked into the intake system it is not pulling vacuum and thus not pulling the vapors out of the charcoal canister leading to the reason I cannot fill my tank and the evap error code.

The second issue I see is with the hose not connected to the evap fuel line. The purge valve and solenoid are open and are pulling in un-metered air causing a lean condition. I have seen many people post about the blue T connector leaking, causing issues so seems that should apply here.

I am not sure if either of these assumptions are correct hence why I am posting here. To me this seems like a problem. I called the shop and they said the line was intentionally left off but didn't really give an explanation as to why it was. They said not being able to fill my tank was most likely an issue with my charcoal canister. Which to me seems a bit convenient that it would fail at the exact same time as all the work I had done but idk. My tuner said he would email me the reason for leaving the line off but he has proven to not always be the best about replying in a timely fashion, hence why I am posting here. I just want to see if anyone has any input on if my assumptions are plausible at all or if I just have a misunderstanding of how the evap system works.

thanks
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Old 06-05-2019, 08:52 PM   #2
adventures91
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Member#: 349672
Join Date: Mar 2013
Chapter/Region: NWIC
Location: Seattle WA
Vehicle:
2003 WRX Wagon
Blue

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Well my tuner said it wouldn't be a problem to re-hook up the vacuum line to the evap vent line I no longer am getting the evap error code or at least have not gotten it yet. However I am still getting idle issues. I had an after market bpv since I am running at a higher boost pressure but tried switching in the stock unit because I know after market bpv's can sometimes leak. I really feel like it is most likely the tune but if there is anything else to check would be open for input and help.
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Old 06-05-2019, 09:00 PM   #3
adventures91
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Location: Seattle WA
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2003 WRX Wagon
Blue

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Here is a video with my foot barely on the throttle not moving. You can see the revs bouncing up and down on there own. Not sure if this is a result of the big injectors or helpful.


Last edited by adventures91; 06-06-2019 at 12:55 PM.
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Old 06-11-2019, 12:15 AM   #4
Romy
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Location: Central NV
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2002 Outback STI

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My advice may not be relevant as I don't have a WRX to test on. But, I have an STI swapped Outback and occasionally get a P0457, but never have the issues you've described. However, they sound a heck of a lot like a bad evap purge valve. It's on/under the intake manifold of the EJ257 as well as NA EJ25, and when bad, will do what you're describing. Happened to me a couple of times on a couple of different Subaru's. Easiest way to check it is to put the Subie into test mode where it'll cycle valves, solenoids, and fans. Connect your green plug under the drivers side dash together, turn the key on, and see if you feel the solenoid clicking.

For my swap I sort of threw together the evap system from an 04 H6 Outback, my 02 Outback, and an 04 STI, but they're all similar (but obviously not enough to avoid my P0457...it happens ever ~1000 miles and I just clear it). There's also an evap valve or two on/near the charcoal canister in the rear of the car. If you've got the green plug connected, might as well check if those are clicking as well. Note that the click should be fairly resounding and not a weak tap. Best check would be to take the valves/solenoids off and try to blow through them and see if the solenoid can stop the air.

Hope that helps.
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Old 06-11-2019, 02:57 AM   #5
redrex009
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Similar problem in my WRX... Found to be a failed evap solenoid delete. Put an OEM solenoid back in problem fixed
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Old 06-11-2019, 11:20 AM   #6
adventures91
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Join Date: Mar 2013
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Location: Seattle WA
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2003 WRX Wagon
Blue

Default

@Romy I will check out the valves on the back of my car. I already replaced the front evap solenoid so I assume that should be working but will double check it as well.

@redrex009 I replaced the front evap solenoid and I will be checking out the rest of the system

Thanks for the advice
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Old 06-11-2019, 11:24 AM   #7
redrex009
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lightning red

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Good luck! Don't forget to podt the resolution!
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Old 08-08-2019, 04:21 PM   #8
adventures91
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Blue

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Just wanted to update with my progress.

Replaced the evap solenoid and rehooked up the return line and haven't been getting the evap error since.

The fuel tank issue was a bad fuel tank sending unit. Once that was replaced the gauge is reading that the tank is full again. Just happened to be a coincidence that it was at the same time as everything else.

Cleaned the IACV and throttle body and replaced the tpms sensor while I had the throttle body off. After doing that the car seems to be stalling less at least.

Added some fuel pressure dampers to my fuel rails and had my tuner adjust the cl/ol delay and now the hesitation is gone.

At this point i am still trying to figure out the idleing issues the car is still stalling and the idle is still rough and the idle fluctuations are still there. I drove the car without the O2 sensor plugged in to see if it was an issue with the O2 sensor but the car basically drove the same with or without it plugged in. I reached out to my tuner again to see if he had any more ideas or if he thought the injector scaling/latency could be off. Waiting to hear back on that.

At this point I am thinking about looking into taking the car to a different tuner to see if they can offer any insight. Will see what my current tuner responds with. Really hope I can eventually get the idle solved.
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Old 10-30-2019, 11:46 AM   #9
adventures91
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Join Date: Mar 2013
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Location: Seattle WA
Vehicle:
2003 WRX Wagon
Blue

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Final got my issue resolved it ended up being an issue with the size of my injectors just being to large. I went with what my shop suggested. But I think think the 1700cc injectors were just to much for my setup and my tuner just couldn't make them idle correctly. I switched back down to the 1000cc injectors I originally had in the car and still making the same power and didn't run out of injector.
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