# Can the Evap system cause a boost/vac leak?



## warranty225cpe (Dec 3, 2008)

So I used a bicycle pump to try to pressurize my system to look for leaks. Turns out that it's not a good way to do it (not enough power). But when I did it, i heard a hiss coming from what I "thought" was my passengers side intercooler hose because I just did my FMIC. I just replaced my stock hose with a forge hose and tightened the **** out out of it. So I'm pretty sure it's not leaking. Pulled out the pump again just to see if the hiss was still there, and of course it was. Upon closer inspection it started to sound like it was coming from my evap system where the "blue balls" are (mine happen to be black). Do these things leak enough to cause a boost/vac leak? I left that stuff in when I did my deletes. Should I yank this crap completely and cap off the lines? Here's a picture of how I have things right now.


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## madmax199 (Oct 28, 2009)

Yes, Evap stuff can leak under positive pressure. I had that valve in between the tank and PS reservoir in your pic leaking internally. Remember I told you the bicycle pump would not work, you need compressed air with a regulator to keep the pressure constant(even with the leak).


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## PLAYED TT (Oct 17, 2010)

It can, but it would throw a code. have you scanned it?


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## warranty225cpe (Dec 3, 2008)

madmax199 said:


> Yes, Evap stuff can leak under positive pressure. I had that valve in between the tank and PS reservoir in your pic leaking internally. Remember I told you the bicycle pump would not work, you need compressed air with a regulator to keep the pressure constant(even with the leak).


Yeah, I understood that the pump isnt enough. But I at least found this leak with it. Once I get this sorted out Ill do a proper test. 
Are you talking about the valve that plugs into the black tank right in the center of the pic? I noticed that mine doesnt even seem to seal in the spot that its plugged into. I guess i need to figuure out how to remove that and cap those lines. Cant i just cap the line thats at 12 oclock of the check valve, and the one thats at the 9 oclock of the valve and remove the big canister part?



PLAYED TT said:


> It can, but it would throw a code. have you scanned it?


Yeah, I get the CEL "16825 evap Emissons control System incorrenct purge flow". But I always thought that it was because of the resistor I put in there.


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## madmax199 (Oct 28, 2009)

warranty225cpe said:


> Yeah, I understood that the pump isnt enough. But I at least found this leak with it. Once I get this sorted out Ill do a proper test.
> Are you talking about the valve that plugs into the black tank right in the center of the pic? I noticed that mine doesnt even seem to seal in the spot that its plugged into. I guess i need to figuure out how to remove that and cap those lines. Cant i just cap the line thats at 12 oclock of the check valve, and the one thats at the 9 oclock of the valve and remove the big canister part?
> 
> 
> ...


Yup, take the tank, valve and solenoid out and cap everything off. IIRC you also need to vent the tank out, on one of the two white synflex lines and cap the other.

Normally with an evap delete, you get more than one code. The resistor took care of the rest but the incorrect flow code has to be removed from the emission checks via software.


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## warranty225cpe (Dec 3, 2008)

madmax199 said:


> Yup, take the tank, valve and solenoid out and cap everything off. *IIRC you also need to vent the tank out, on one of the two white synflex lines and cap the other.*Normally with an evap delete, you get more than one code. The resistor took care of the rest but the incorrect flow code has to be removed from the emission checks via software.


Not sure what you mean.. venting the tank?


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## PLAYED TT (Oct 17, 2010)

madmax199 said:


> Yup, take the tank, valve and solenoid out and cap everything off. IIRC you also need to vent the tank out, on one of the two white synflex lines and cap the other.
> 
> Normally with an evap delete, you get more than one code. The resistor took care of the rest but the incorrect flow code has to be removed from the emission checks via software.


Yeah you need a tune to remove that improper air flow code. Nothing else will fix it.


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## warranty225cpe (Dec 3, 2008)

PLAYED TT said:


> Yeah you need a tune to remove that improper air flow code. Nothing else will fix it.


I just erase it with my liquidTT.

Not really worried aboutthe code. More so the fact that I can hear it leaking.


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## madmax199 (Oct 28, 2009)

warranty225cpe said:


> Not sure what you mean.. venting the tank?


Now that I think about it, venting the tank was needed because I also deleted the charcoal canister.
You guys are only doing a half evap delete, I did a full delete. If you go the full delete route the tank would need to be vented.


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## PLAYED TT (Oct 17, 2010)

warranty225cpe said:


> I just erase it with my liquidTT.
> 
> Not really worried aboutthe code. More so the fact that I can hear it leaking.


you and your fancy gauges


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## warranty225cpe (Dec 3, 2008)

madmax199 said:


> Now that I think about it, venting the tank was needed because I also deleted the charcoal canister.
> You guys are only doing a half evap delete, I did a full delete. If you go the full delete route the tank would need to be vented.


 So I can just cap those 2 lines and gut that thing? Sweet! Ill have to dig into that tomorrow


PLAYED TT said:


> you and your fancy gauges


I know a lot of people think the liquid isnt 100% reliable, but I cant imagine not having one. Its paid for itself for sure. Being able to pull up a cel and reset it without even having to turn the car off is great. Not to mmention all of the other features, TB reset etc.


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## madmax199 (Oct 28, 2009)

warranty225cpe said:


> So I can just cap those 2 lines and gut that thing? Sweet! Ill have to dig into that tomorrow
> .


Cap one and vent one, or you'll have a pretty hard time filling up after some pressure builds up in the tank :beer:.

*Edit* I believe I also added a one way check valve in the vented line, so pressure can escape but moisture stays out. I have done it so long ago that the specifics are getting forgotten, but it's as basic as it gets.


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## warranty225cpe (Dec 3, 2008)

madmax199 said:


> Cap one and vent one, or you'll have a pretty hard time filling up after some pressure builds up in the tank :beer:.


Which one should i vent? Or does it matter? And by vent youo mean to just leave it open....?


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## madmax199 (Oct 28, 2009)

warranty225cpe said:


> Which one should i vent? Or does it matter? And by vent youo mean to just leave it open....?


 It don't think it matters which one you vent. By "venting" I mean leaving it open or venting to the atmosphere so pressure in the tank has a place to escape. Like I said, you may want to include a check valve on the vented one so pressure flows out but nothing goes in :beer:.


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## warranty225cpe (Dec 3, 2008)

So to summarize... I can cut those 2 lines and add acheck valve to either to keep the line from pulling vac in. How Do I know if I have the right line plugged/vented (If there is a difference)?


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## madmax199 (Oct 28, 2009)

warranty225cpe said:


> So to summarize... I can cut those 2 lines and add acheck valve to either to keep the line from pulling vac in. How Do I know if I have the right line plugged/vented (If there is a difference)?


There is no difference, you are just giving pressure that builds in the tank, a way to escape.


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## warranty225cpe (Dec 3, 2008)

madmax199 said:


> There is no difference, you are just giving pressure that builds in the tank, a way to escape.


But isnt the tank the part im removing..?


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## madmax199 (Oct 28, 2009)

warranty225cpe said:


> But isnt the tank the part im removing..?


 You are removing the charcoal canister, the tank I'm referring to is the fuel tank.


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## warranty225cpe (Dec 3, 2008)

madmax199 said:


> You are removing the charcoal canister, the tank I'm referring to is the fuel tank.


"light bulb!" lol

Thanks man


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## Doooglasss (Aug 28, 2009)

The only reason you should worry about the CEL is if you live in a state where they OBD2 check your car for readiness codes. Here in NY you can only have one readiness block fail, more than that and you don't pass. You also don't pass if there is a CEL on the dashboard.

When you clear codes with any kind of OBD2 interface it also resets all the readiness codes. Software tuners like Unitronic or Eurodyne can program in your ECU to force the readiness codes to pass immediately.

I jumped the gun years ago and pulled all the emissions junk out then couldn't pass emissions for over two years due to my tune- was unable to register the car in NY and took it off the road and decided to big turbo it. All I'm saying is just remember there are other costs involved.


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## warranty225cpe (Dec 3, 2008)

No emissions in Florida. But thanks for sharing.I might switch to Uni .


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## warranty225cpe (Dec 3, 2008)

So since I had a few check valves laying around I decided to cap both lines with valves. That way there's no "which one should I vent/cap". I didn't pull the balls out yet though. I just wanted to get rid of that leak. It feels MUCH better now that I got rid of that leak.


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## madmax199 (Oct 28, 2009)

warranty225cpe said:


> So since I had a few check valves laying around I decided to cap both lines with valves. That way there's no "which one should I vent/cap". I didn't pull the balls out yet though. I just wanted to get rid of that leak. It feels MUCH better now that I got rid of that leak.


Nooooooooo, maybe I'm giving you the wrong explaination. You need to cap (not with check valves) the lines left open by the plastic tank you deleted by the overflow tank. 

The charcoal canister is a black square box in the back of the car, by the fuel tank. A full delete, like I did, also includes removing it, and that's when the venting of the fuel tank takes place with a check valve.

This is what the charcoal canister looks like.

http://cgi.ebay.com/ebaymotors/FUEL-EVAP-CHARCOAL-CANISTER-Audi-TT-2000-00-/150464507833


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## Doooglasss (Aug 28, 2009)

wow- didn't realize I have $100 bucks sitting in a box in my basement...


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## warranty225cpe (Dec 3, 2008)

madmax199 said:


> Nooooooooo, maybe I'm giving you the wrong explaination. You need to cap (not with check valves) the lines left open by the plastic tank you deleted by the overflow tank.
> 
> The charcoal canister is a black square box in the back of the car, by the fuel tank. A full delete, like I did, also includes removing it, and that's when the venting of the fuel tank takes place with a check valve.
> 
> ...


Ok, a little scared now.. Did I cut the wrong lines?


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## madmax199 (Oct 28, 2009)

warranty225cpe said:


> Ok, a little scared now.. Did I cut the wrong lines?


Just cap everything properly, it's just evap crap.


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## warranty225cpe (Dec 3, 2008)

Oh, ok. So its not gonna hurt anything since I have the valves in because I'm not letting them pull vac from the atmosphere right? And since those lines will only ever see vac, I'm ok..?


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## madmax199 (Oct 28, 2009)

warranty225cpe said:


> Oh, ok. So its not gonna hurt anything since I have the valves in because I'm not letting them pull vac from the atmosphere right? And since those lines will only ever see vac, I'm ok..?


You can leave the valves in but still cap the end of every line that's open to the atmosphere.


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