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Discussion Starter #1
Hey guys. I think I have a boost leak since my engine sounds slightly different. The car doesn't feel as if it pulls as hard as it used to. And I've noticed a drop in MPG. I've been reading that you can make your own cap to run the boost leak test. Just wondering if anyone has done this on their 09 or 08 wrx with stock intercooler. Where do you place the cap? right behind the air filter? or right behind the turbo?
 

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Check this thread.
http://www.romraider.com/forum/viewtopic.php?f=33&t=7374&p=68974#p68974

If you pressurize at the inlet, you should disconnect the line to the evap solenoid,and the breathers and plug them off. You can also disconnect a hose off the tube off the turbo if you are running a fmic.
here is my tester made of home depot parts and some spare silicone couplers laying around.
These are designed to go into an air compressor.


You can also use a plastic cap and drill a whole for a valve stem to go in it and pump it up with a tire pump if that is all you have.

Most leaks will show by 10 PSI or so, and if there is a boost leak it won't hold pressure at all, you will also hear hissing from the leak. It is normal for the car to hold for about 15 seconds or so. Also don't worry about leaks you find in the joints of the pcv and breather systems, they are not designed to handle boost and will never see boost in daily operation.
 

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Discussion Starter #3
Thanks eric. I've been watching a few vids on boost leak test on youtube the past few days. Looks like a pretty straightforward setup. Hopefully I can rig up something easy and find a leak (assuming I do have a leak).

When you said disconnect the evap lines and breathers... are those the small lines that connect to the intake tube? Do you happen to know off hand how many there are? So i can just put a cap on those and then hose clamp them on right? Leave the oil cap off also right?

What's the normal boost level on a stock 09wrx? (I went back to stock flash until I find all the issues or nonissues... btw, going back to stock from TP Stage 1 is such a disappointment! I didnt realize how nice TP stage 1 was until it's removed)

side note... I went to the dealer today and they said they could check if anything is wrong with the car. They never heard of a boost leak test. I was kind of surprised since they have so many turbos. Anyhow, they found nothing as I expected.
 

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front to back the lines are Purge valve, boost control solenoid return, head breather, crankcase breather(on top). To be honest I usually just clamp off the evap line. And just not pressure the car above 10-12 PSI for safety. If you have a leak, it will show at that pressure. No real need to pressure up to target boost unless you were checking for a leaking bov.

If you can do some logs of idling, cruising and full boost. I can tell if you have a boost leak. Post the logs here and I will respond so evveryone can know how to read logs to look for boost leaks.
 

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Discussion Starter #5

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I can tell you don't have a boost leak. engine load seems normal, if you had a boost leak, engine load would be much higher. probably by about 30%
The problem is likely related to the high temps. I recently realized that the stock compensations at these high intake temps is a bit much, just adjusting the intake temp compensation a little bit will bring the car back to life. Sometimes a degree or 2 of timing can do wonders. The CAI's don't suffer quite as much as the stock airbox guys.
 

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Discussion Starter #7
So no need for me to build the leak tester then huh? THat's fine w/ me. makes my life a little easier.

Regarding your timing comment... so does TP stage 1 already compensate the engine timing by "a degree or 2" over stock? Or are you saying adjust the timing beyond the current TP Stage 1?
 

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homer, just fyi, if you ever do need to do a boost leak test, soapy water is the ish for finding leaks since it will bubble like a mofo on even the smallest of leaks. just spray it at all couplers and viola!

also if you are in atl, check out topspeed if you ever do go protune. (or eric, i woulda gone with eric but i have meth and he didnt want to try and tune it remotely since it(meth) complicates things -- dont blame him :) )
 

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So no need for me to build the leak tester then huh? THat's fine w/ me. makes my life a little easier.

Regarding your timing comment... so does TP stage 1 already compensate the engine timing by "a degree or 2" over stock? Or are you saying adjust the timing beyond the current TP Stage 1?
Send me an email with your mods, I'll send you a revised map and do some data logs and I can give you your power back!
 

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Discussion Starter #10
Eric,

Thanks again for your continued support of the forum and users. I really appreciate it. I'm going to wait a little bit before I send you anything. I had an moment.. see below

All,

This is a little embarrassing... I found out why my MPG went down. It was my warehouse priced gasoline! I started pouring Costco gas about a month or two back. Well today I poured Quiktrip (QT) gas and my mileage gauge immediately went up to 24ish range. With the Costgo gas I only get 20mpg MAX, that's with w/ cruising and a tiny bit of stop and go. On the QT I was getting 26/27ish cruising and then w/ some stop and go, i'm around 24ish. So for everyone else, the increased mileage is worth more than the $2 or $3 per tank I save w/ the warehouse gas. In terms of performance, I THINK I can also feel a tiny bit of difference when using QT over Costco gas.

Now I'm excited about flashing back to TP Stage 1. When I originally flashed Stage 1, I was on the warehouse gas craze...
 

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I have seen this before. I never use grocery store, generic, or shopping club fuels. I try to stick to top tier fuels, when I'm not on e85. They generally give you the best MPG and therefore value.

From wikipedia
In 2004 the standard was adopted by just a few gasoline distributors, Chevron,[sup][2][/sup] QuikTrip, Kwik Trip, Conoco-Phillips, Shell, Entec Stations, and MFA Oil Company. Since then many gasoline distributors have met the proprietary standard and it can be found in numerous gas stations all over North America.[sup][3][/sup][sup][4][/sup] ExxonMobil, Aloha Petroleum, KwikTrip, KwikStar, Somerset Refinery Inc., Tri-Par Oil Company, Shell Canada, Chevron Canada, Sunoco Canada and Petro Canada have since received Top Tier recognition.[sup][5][/sup] Meeting this standard allows gasoline marketers to differentiate themselves from their competition. All stations selling the brand must meet Top Tier standards before the brand is qualified.[sup][5][/sup]
 

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I decided to write up the proper steps to all this

Turbo Inlet the correct way.
Well, the correct way to do it cap off 3 lines to the inlet hose, The PCV, the crankcase breather and the evap purge solenoid. Basically the only hoses going to the inlet that stay are the BPV recirc and the boost control solenoid return.
1. The easy one is the Evap Purge solenoid(on the inlet at the front of the car),
2. The pcv Is still easy. The breather hoses go from the inlet to each side of the engine. pull these off the tube on each side of the engine and cap them off.
3. The Crankcase breather. This is tricky to get to and requires removing the pcv valve from the hose running to the block and blocking off the line at the pcv valve. You will have to remove the intercooler to access this.
4. Remove the Oil Cap.

If you have a Grimmspeed AOS installed you just made life easier. Steps 2, 3 and 4 can be skipped and replaced by removing the middle hose on your AOS. and plugging off the hose. You have effectively removed the oil cap because the Center line is left open.
Just a note though the lines going to the AOS are never designed to see boost so you may hear boost leaks here but they are not important.

With other catchcan setups you basically disconnect the lines running from the inlet to the catch can and block them off, Skipping steps 2, and 3. You will still have to remove the oil cap.


Quick and Dirty Inlet testing
The not recommended or endorsed but quick and easy way is to do it. This is a use at your own risk kind of thing.

1. disconnect the line running to the evap purge valve and plug it off.
2. pressure test the inlet but only to about 10 PSI or so. It will most likely not cause damage to the cam seals and you will be able to hear most leaks. Be aware that there are many tubes not designed to hold boost and these shouldn't be worried about.

FMIC leak testing
Now if you are Front mounted the easy way to go is to disconnect the boost tube to the turbo and apply pressure here, You should also remove the oil cap.
 

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^^ Thanks for that post, Eric! Definitely going to bookmark it.

As always, thanks for being a tremendous resource for our community!
 

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Do you have any pictures of exactly which tubes to cap off? I've got a boost leak tester and a compressor, and I know that I need to remove the oil cap, but that's it. Terms like "crankcase breather and the evap purge solenoid" have no meaning to me, I'm not a mechanic :(
 

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MODS - How about making this a sticky in the DIY section, hmmm?
Eric - Excellent advice, as always!
 

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I decided to write up the proper steps to all this

Turbo Inlet the correct way.
Well, the correct way to do it cap off 3 lines to the inlet hose, The PCV, the crankcase breather and the evap purge solenoid. Basically the only hoses going to the inlet that stay are the BPV recirc and the boost control solenoid return.
1. The easy one is the Evap Purge solenoid(on the inlet at the front of the car),
2. The pcv Is still easy. The breather hoses go from the inlet to each side of the engine. pull these off the tube on each side of the engine and cap them off.
3. The Crankcase breather. This is tricky to get to and requires removing the pcv valve from the hose running to the block and blocking off the line at the pcv valve. You will have to remove the intercooler to access this.
4. Remove the Oil Cap.

If you have a Grimmspeed AOS installed you just made life easier. Steps 2, 3 and 4 can be skipped and replaced by removing the middle hose on your AOS. and plugging off the hose. You have effectively removed the oil cap because the Center line is left open.
Just a note though the lines going to the AOS are never designed to see boost so you may hear boost leaks here but they are not important.

With other catchcan setups you basically disconnect the lines running from the inlet to the catch can and block them off, Skipping steps 2, and 3. You will still have to remove the oil cap.


Quick and Dirty Inlet testing
The not recommended or endorsed but quick and easy way is to do it. This is a use at your own risk kind of thing.

1. disconnect the line running to the evap purge valve and plug it off.
2. pressure test the inlet but only to about 10 PSI or so. It will most likely not cause damage to the cam seals and you will be able to hear most leaks. Be aware that there are many tubes not designed to hold boost and these shouldn't be worried about.

FMIC leak testing
Now if you are Front mounted the easy way to go is to disconnect the boost tube to the turbo and apply pressure here, You should also remove the oil cap.

I have literally spent hours all over many Subaru Forums, and you have given me the most concrete answer. but like the poster above me I am unsure of where to plug the crank case breather.

I have a 2003 Wrx ej205, is this different I realize the PCV on my car actually screws into the manifold, Do I want to cap off the PCV directly after its short 3 inch tube? and is the breather the other tube that connects to the pcv tubing?
going to remove intercooler and post pictures of what I think I am doing after work tomorrow, I want to do this test as I installed a boost gauge and only running -16in/hg vacuum at idle.


I have a open hood scoop because my car is a 99 legacy Gt with 03 wrx engine, I think the Intercooler potentially may be my issue.
 

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I decided to write up the proper steps to all this

Turbo Inlet the correct way.
Well, the correct way to do it cap off 3 lines to the inlet hose, The PCV, the crankcase breather and the evap purge solenoid. Basically the only hoses going to the inlet that stay are the BPV recirc and the boost control solenoid return.
1. The easy one is the Evap Purge solenoid(on the inlet at the front of the car),
2. The pcv Is still easy. The breather hoses go from the inlet to each side of the engine. pull these off the tube on each side of the engine and cap them off.
3. The Crankcase breather. This is tricky to get to and requires removing the pcv valve from the hose running to the block and blocking off the line at the pcv valve. You will have to remove the intercooler to access this.
4. Remove the Oil Cap.

If you have a Grimmspeed AOS installed you just made life easier. Steps 2, 3 and 4 can be skipped and replaced by removing the middle hose on your AOS. and plugging off the hose. You have effectively removed the oil cap because the Center line is left open.
Just a note though the lines going to the AOS are never designed to see boost so you may hear boost leaks here but they are not important.

With other catchcan setups you basically disconnect the lines running from the inlet to the catch can and block them off, Skipping steps 2, and 3. You will still have to remove the oil cap.


Quick and Dirty Inlet testing
The not recommended or endorsed but quick and easy way is to do it. This is a use at your own risk kind of thing.

1. disconnect the line running to the evap purge valve and plug it off.
2. pressure test the inlet but only to about 10 PSI or so. It will most likely not cause damage to the cam seals and you will be able to hear most leaks. Be aware that there are many tubes not designed to hold boost and these shouldn't be worried about.

FMIC leak testing
Now if you are Front mounted the easy way to go is to disconnect the boost tube to the turbo and apply pressure here, You should also remove the oil cap.
Can you explain why you would disconnect the evap purge valve? Does it not handle boost? What happens when it sees boost during normal operation?
 
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