FAQ: Subaru EVAP Purge Control Solenoid Valve Information for EJ205

[IA Performance]

After receiving quite a few questions regarding the EVAP Purge Solenoid hose routing we figured it best to start a FAQ thread dedicated to the ej205 (WRX 2.0L).

Note: We are learning more about the system along the way so please bear with us as we aren't experts in this field.

General EVAP FAQs
What is EVAP
Evaporative Emission Control System

What is the function of an EVAP System?
I tried to make this as short as possible: The EVAP system was designed to decrease fuel vapors as a source of pollutant. You see, gasoline vapors contain hydrocarbons. These hydrocarbons mix with air and sunlight to create smog, a pollutant. To curtail the smog output the car's gas tank vent's the fuel vapors, via the vent tube, to the charcoal canister, which serves as a temporary holding tank. So what's inside of a charcoal canister? You guessed it, charcoal. This activated charcoal absorbs the vapors and holds them until the car is fully warmed and driving. At this point, the ECU sends a few signals out. One, to the charcoal purge alerting it to open, as well as one to the EVAP purge solenoid, alerting it to open under vacuum. The vapors are then drawn from the charcoal canister, by vacuum, into the intake manifold, where they are ultimately burned up.

For a more in depth description we suggest doing a internet search. There are several good sources out there. *

Subaru WRX ej205 2002-2005 Specific FAQs
Is the EVAP Solenoid Open or Closed when at rest (no power)?
Closed

Is there a specific flow direction for the EVAP purge solenoid?
Through research, it appears the direction does not matter since the solenoid is simply creating an open or closed path for which the vapors to flow. When open, air can pass either way through the solenoid. Although, we still recommend following the factory Subaru diagrams for your specific model.

Is there a specific flow direction for the purge valve?
The Purge Valve (round black thing) is direction specific and should have an arrow painted on the front of it. Please take note to diagram A for direction.

Which hose goes where?
Please see the diagram below for 2002-2005 ej205 applications. Note, if you have a 2.5L turbo motor please refer to our EVAP purge FAQ for ej25 turbo models here.



It looks like spaghetti, can I decrease the EVAP clutter?
Yes, you can install the purge control solenoid without the use of the Purge Valve (black round item with 3 ports on it). A perfect example of a EVAP system that does not require the Purge Valve is the JDM Subaru ej207. This model still uses the same EVAP purge solenoid, but the mess of hoses is cleaned up considerably (only 2 hoses now). A WRX ej205 can be setup in the identical fashion. There does not appear to be an affect on performance, nor does it trigger a CEL. In short, all it takes to run the EVAP purge solenoid is the valve, 2 hoses, and 2 hose caps to block off the unused nipples. Disclaimer: We do not know how this affects pollutant levels.



Do I need to be concerned with leaks (vacuum as well as pressure)?
Yes, a pressure, as well as vacuum, leak can have a great affect on the way the car performs. A vacuum leak will allow non metered air into the intake manifold, which creates a lean condition when the intake tract is in vacuum. As the car builds positive pressure (PSI) it will then allow air form the intake tract to escape through this leak. Since the ECU is unaware of this leak it continues to add the same amount of fuel, which leads to a rich condition during positive manifold pressure conditions (full throttle is especially affected).

We suggest using zip ties at any hose connection on the intake manifold, EVAP system, as well as turbo inlet tube. P.S. don't forget to do the same for the Fuel Pressure Regulator hose

Below are the most common EVAP related leaks that we've run across that will affect the performance of the ej205:
1) The junction of hoses at the blue 'T' connector, located behind the P/S pump. As the hoses dry out they become lose and come apart.

2) The next most common leak area is the ~1" long, straight, hose going from the intake manifold to the Purge Valve. Since there are no hose barbs at either end of this hose it can easily come off the manifold and/or Purge Valve. As a rule of thumb, any hose nipple should have a barbed end on a boosted motor. If this hose is lose we suggest replacing it with a new one. Just about any vacuum line will do, assuming it has the same ID.

3) One of the more expensive leaks is created when one of the EVAP Purge Solenoid nipples is broken off. This seems to happen the most when people [cough] carelessly install an aftermarket turbo inlet tube. If this happens do NOT glue it back together. Rather, spend the $100+ and replace the unit with a new one from Subaru. There are way too many negative side affects with a broken valve (pollution, loss of power, etc).





*rabech27 contributed the following on 9/18/2014:
The charcoal you refer to is actually activated carbon pellets. I worked at the only plant in the world that can make the grade of carbon that goes into those canisters. Mead Westvaco is the company that makes it and their plant is located in Covington, Virginia. I worked there as an engineer for three years. It is made with sawdust and phosphoric acid, heated in a large rotary kiln (100 ft long), then shaped into pellets, and run through another kiln that activates it and creates the adsorption characteristics that hold the fuel vapors. The activated carbon has millions of pores that hold the fuel vapor molecules until the purge system opens and purges the vapors off the carbon. Just thought I'd share that with you in case you were interested.

* Registered users of the site do not see these ads.

[IA Performance]

We will continue to add more information to these first few posts as the thread grows.

[IA Performance]

One more space, just in case.

[Unabomber]

I'm going to sue!

[IA Performance]

Una -I'm trying to convince our head designer, my wife, that we need to do our own illustrations. For the time being we'll leave the above as-is and cross our fingers for that the strong arm of Subaru does not come down on us.

[Unabomber]

Not hatin on the illustrations, just playing with you as I "own" the FAQ title around here. If you do have someone that does illustrations though, what we NEED is a slick illustration for 2008+ exhausts to show what is what on the WRX and STI.

[IA Performance]

Unabomer - pop me a PM or email with more specifics and I'll see what we can turn out for the exhausts.

Stephen

[Unabomber]

PM away, mucho gusto!

[WrxFtw02]

I just got rid of mine altogether. Cap off the inlet nipple, and the nipple on the intake manifold. I left a piece of hose to vent from the nipple under the intake manifold. Turn off the CEL and your good to go!

[IA Performance]

WrxFtw02 - Yes, this entire system can be deleted, including charcoal filter, but the goal of this post is to explain why our cars have these parts and the environmental impact they serve.

Stephen

[lino129]

I have been having some issues with my 02 WRX, well since i've owned it mostly due to careless previous owners (long story, wont get into it) and Infek told me to check and see if everything was connected and sure enough, the hose to the blue connector (unsure of technical name) was popped off, in my attempts to put it back on the line to the intake duct snapped. I went to the local parts store and got some generic vacuum line and reconnected everything and started the car up and it idles HORRIBLY, jumps between 1k and 1.1k RPM and sounds like it could die at any second. if my car was tuned (PO had a local kid tune it) without everything connected would that explain the problem?

[IA Performance]

Originally Posted by lino129

I have been having some issues with my 02 WRX, well since i've owned it mostly due to careless previous owners (long story, wont get into it) and Infek told me to check and see if everything was connected and sure enough, the hose to the blue connector (unsure of technical name) was popped off, in my attempts to put it back on the line to the intake duct snapped. I went to the local parts store and got some generic vacuum line and reconnected everything and started the car up and it idles HORRIBLY, jumps between 1k and 1.1k RPM and sounds like it could die at any second. if my car was tuned (PO had a local kid tune it) without everything connected would that explain the problem?

Assuming the car was tuned with the hose off then the fuel trims will definitely be far out of alignment. For the time being you can try resetting the ECU to see if the zeroed out fuel trims do better at idle for you.

Leak post turbo, pre intake valves (in the inter cooler or intake manifold)
This will result in a lean condition at idle and rich condition at full throttle. Since you've now fixed the leak the car is probably overly rich at idle and will be most likely lean at full throttle.

Leak between the MAF and turbo
I was not sure if you snapped off one of the turbo inlet nipples. If so, be sure to replace it right away. A leak here can create a small lean condition during idle, but a huge lean issue during full throttle.

Both of the above conditions can create an unstable idle and unstable engine. In short, do a pressure test to ensure there are no other leaks and then get a tune ASAP. If you have a COBB accessport then we can assist through our E-Tuning service (click the image):


Let me know if you have additional questions that I can assist with.

[email protected]

[lino129]

Originally Posted by IA Performance

Leak between the MAF and turbo
I was not sure if you snapped off one of the turbo inlet nipples. If so, be sure to replace it right away. A leak here can create a small lean condition during idle, but a huge lean issue during full throttle.

Both of the above conditions can create an unstable idle and unstable engine. In short, do a pressure test to ensure there are no other leaks and then get a tune ASAP. If you have a COBB accessport then we can assist through our E-Tuning service (click the image):


Let me know if you have additional questions that I can assist with.

[email protected]

No, it was just the hose that snapped. There is alot more to my issues than just the purge valve, (VF39 tuned at 7PSI, multiple junk Ebay parts, 100% atmospheric BOV...) There's quite a few issues I have to address. But no I don't have a AP I was going to go the open source route. (PO had a TurboXS UTEC that no tuners I've talked to will even touch)

[IA Performance]

Wow, it sounds like you have Pandora's box for a car! Your money will be best spent trouble shooting and correcting problems first and then having it tuned. If a tune is done with the current state then the problems will most likely hinder the results and possibly damage the motor through time. As for the Utec, you can see if Clark Turner still does tuning with those. He was a wiz with them back in the day, but I believe he too has moved on to more technologically advanced tuning methods (OS, Cobb, etc).

Keep in mind, the AccessPORT may cost more up front when compared to an OS tune, but you are getting a tool, not just a tune It works as a gauge, trouble code reader, holds tons of maps, has customer support in the event something goes wrong.There is a huge dealer network, whereas OS you are left making a post on a forum and hope someone comes to your rescue. Also, it does not require the use of a laptop and tactrix cable. The final plus is, when you no longer need the AP you can resell the unit and recover money, whereas with OS there is no recovery other than selling off a cord.

Stephen

[lino129]

Yes, yes I do . That's what happens when you buy a car like a WRX without knowing anything about Subarus...
And I would love to only have to spend money on trouble shooting and a tune... but most of the problems come from the parts on the car and the "tune" for them... the PO blew 2 motors running the VF39 at 20+PSI on a stock fuel system... had this local kid tune it to 7PSI... and made it so none of the cluster warning lights ever come on, except the check engine light flashes if there is knock...
And no, Clark doesn't tune with the UTEC anymore, I had talked to him about a tune. And the tuning method is still kind of up in the air, but yes it is pretty much low cost of OS vs the multitude of uses for the AP. and I would have to use a laptop for at least the first few logs, just so I can log with the Wideband. Because the AP doesnt directly support a UEGO but the Access Tuner software for the computer does. haha

[IA Performance]

lino129 - It sounds like the car is finally in the hands of a good owner. Best of luck with the repairs. The CEL should come back on if you remove the Utec, in assumption that is what is blocking them from turning on (there is a feature in it to do so). I'd slap that thing on ebay and try to recoup a few bucks and then meticulously go through the engine. After all, a healthy motor is a happy one

Feel free to drop me a PM, or email, if you have repair questions along the way. I'm one of the few tuners that has also worked on Subarus for the past 11 years.

In regards to wideband logging, there is no need to log the AFR with the data logs. Simply shoot a video from your smart phone and email it. As long as the tach and gauge are in the same frame you will be set. Less clunky than a laptop too Just a thought, although I see and agree with your view.

[email protected]

[shano]

Good thread. I recently broke the purge solenoid installing my inlet. Didn't realize it at first but then when I first started it you could hear the air "sucking" sound. 150$ to replace at local parts store

[lino129]

Yea I like to think so too. unfortunately working at a gas station doesn't really lend a lot of car money.

[ThePunisherGT]

Double post.

-Punisher

[ThePunisherGT]

I'm not sure if you weren't trying to intermingle these two threads but using the pic from this thread that you supplied, I noticed you add a hose where you drew the green line. After many hours reading and rereading I never read anything about what hose size to buy to make the delete or what size nipple plugs you need. Do you have any of those sizes? Just to save a few trips to the store checking and rechecking. Thanks huge!

http://forums.nasioc.com/forums/show...errerid=121305

-Punisher

[IA Performance]

ThePunishedGT - the intention with the new thread was to get one that has the facts of why and what the EVAP system is. I do not have the exact sizes available, but this info should help:

(1) intake manifold nipple cap 1/16" ID
(1) turbo inlet nipple cap 3/16" ID
(1) jumper hose 1/8-3/16" ID (roughly 7-8" long (usually sold by the foot)

Stephen

[ThePunisherGT]

That is PERFECTLY what I was looking for. Thanks so much!!

Does the jumper hose have two different sized ends? Is that the different numbers?

-Punisher

[ThePunisherGT]

Also finding 1/16 cap is turning out to be impossible. Smallest I can find is 1/8.

-Punisher

[IA Performance]

try the 1/8" and report back. My measurements were guesstimates.

Stephen

[ThePunisherGT]

And the jumper hose two numbers?

- Punisher