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Old 11-03-2012, 03:23 PM   #1
Jerembo47
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Impreza WRX 07 WRX TR Boost issue only 6 psi?

Hello, I purchased an 07 wrx from the dealership and it has been pushing only 6 psi boost. I am no mechanic but I do have mechanical skills being in the navy. The car is pretty much stock except for the 5" exhaust. Ive been reading posts on here for over an hour now. I have checked most of the vacuum lines, well the ones I can see on the turbo, MBC, inter-cooler and stock BOV. They are nice and tight. I have reset my ECU and still only 6psi. I'm thinking either my boost gauge is degraded or installed in the incorrect spot. Im not sure if I am getting waste gate only. I have taken some pictures. Also does anyone know where I can find a vacuum diagram? Maybe that will help. Thanks! Let me know if I should post some more pics?










^^^^^This one shows where the boost gauge was tapped^^^^^





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Old 11-03-2012, 05:04 PM   #2
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If u adjust boost with mbc does the boost go up or down???

Is it tuned?
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Old 11-03-2012, 05:07 PM   #3
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No MBC only stock boost controller.
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Old 11-03-2012, 05:07 PM   #4
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And I've never had a tune.
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Old 11-03-2012, 05:10 PM   #5
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Sorry I had an MBC on my old subie. Not this one
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Old 11-03-2012, 05:41 PM   #6
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Quote:
Originally Posted by Jerembo47
Hello, I purchased an 07 wrx from the dealership and it has been pushing only 6 psi boost.

I have checked most of the vacuum lines, well the ones I can see on the turbo, MBC, inter-cooler and stock BOV. They are nice and tight.
On here it says mbc... sounds like u running on wg spring pressure.

Do a smoke test to make sure u don't have a leak.
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Old 11-03-2012, 05:45 PM   #7
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My bad I didnt mean to put MBC I meant stock boost controller.
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Old 11-03-2012, 05:52 PM   #8
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Bcs may be bad.
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Old 11-03-2012, 09:44 PM   #9
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I cleaned the BCS and MAF sensor with maf sensor cleaner in accordance with this http://www.scoobypedia.co.uk/index.p...ontrolSolenoid

And still only 5-6 psi. Im going to try a leak test as soon as I can get the required equipment. Maybe get a new BCS or EBC Also I am going to get a new boost gauge and vac lines. If any one can think of anything else I can try please let me know. Thanks for all the input so far...
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Old 11-03-2012, 09:52 PM   #10
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Ebcs, new vac lines without the pill and a tune or tweak and problem should be solved
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Old 11-03-2012, 10:52 PM   #11
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You are on WG spring pressure something is throwing the car into no boost mode because the ecu is not commanding a higher pressure. I bet its not tuned for that intake, running lean, knocking and the iam is at 0. To test this, disconnect the battery and press the brake pedal, then reconnect the battery. If you make more boost than 7psi on the first WOT run, stay out of boost on your way home and DO NOT drive the car again until you either get a tune or get a stock intake back on it.
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Old 11-04-2012, 04:47 PM   #12
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Quote:
Originally Posted by Leafy View Post
You are on WG spring pressure something is throwing the car into no boost mode because the ecu is not commanding a higher pressure. I bet its not tuned for that intake, running lean, knocking and the iam is at 0. To test this, disconnect the battery and press the brake pedal, then reconnect the battery. If you make more boost than 7psi on the first WOT run, stay out of boost on your way home and DO NOT drive the car again until you either get a tune or get a stock intake back on it.


I have already rest the ECU by disconnecting the battery and it made no difference. This is the way the car came from the dealership. This is my daily driver that I have been driving in this condition for the past 6 months.






I had to get the carb sticker from the dealership so I could pass Cali emissions. The car runs great and is fast. Im thinking where they tapped the boost gauge was in an incorrect location. It is tapped off of the BOV. Would that make a difference in the reading?


And I do realize I spelled gauge wrong on the pic just too lazy to change it.

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Old 11-04-2012, 05:06 PM   #13
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What kind of boost gauge do you have and when you let off the gas what vacuum does it go to?
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Old 11-04-2012, 09:00 PM   #14
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Quote:
Originally Posted by stephens View Post
What kind of boost gauge do you have and when you let off the gas what vacuum does it go to?


It is a glow shift gauge and when at idle it reads about 22 or 23 HG
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Old 11-04-2012, 09:38 PM   #15
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Thats a fine spot to pull the boost gauge from. For some reason the car is on waste gate pressure. You need to figure out why.
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Old 11-04-2012, 09:48 PM   #16
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maybe i just need a basic tune? I know Cobb will charge $500...
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Old 11-04-2012, 09:53 PM   #17
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The wife just informed me the dealership said the previous owner blew the original engine and they installed a new engine about 1000 miles before I bought it...
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Old 11-04-2012, 09:59 PM   #18
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I had a problem running at wastegate spring pressure after I swapped turbos (going from VF39 back to stock TD04). The newer turbo had the vacuum lines already on it, so I used those. Turns out, those lines were missing the restrictor pill. I fished the pill out of the old lines, inserted in the correct vacuum line, and voila, hitting correct boost again.

If you haven't already, make sure that you have the restrictor pill in there, and in the correct line. If it's not in there, you could easily have this exact problem.

If the 06 is the same as my 04 as far as restrictor pills goes, this might fix your problem. If I goofed that up, my apologies.

Use this diagram for reference (where the pill goes):

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Old 11-04-2012, 10:02 PM   #19
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Quote:
Originally Posted by lastsnare View Post
I had a problem running at wastegate spring pressure after I swapped turbos (going from VF39 back to stock TD04). The newer turbo had the vacuum lines already on it, so I used those. Turns out, those lines were missing the restrictor pill. I fished the pill out of the old lines, inserted in the correct vacuum line, and voila, hitting correct boost again.

If you haven't already, make sure that you have the restrictor pill in there, and in the correct line. If it's not in there, you could easily have this exact problem.

Can you see or feel the pill inside the vac line? like a bulge or something? Cause I was feeling and looking to see if I could tell which line it was in and I could not tell.
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Old 11-04-2012, 10:09 PM   #20
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Quote:
Originally Posted by Jerembo47 View Post
Can you see or feel the pill inside the vac line? like a bulge or something? Cause I was feeling and looking to see if I could tell which line it was in and I could not tell.
You should be able to feel a little hard ball in there yes (that's what she said), but you might not be able to see it. It doesn't matter where in that one vacuum line it is, as long as it's in the right line. The vacuum lines might be fairly stiff, but if you squeeze it hard with your fingers along the few inches of its length, you should be able to feel something. Worst case scenario, you could carefully slide off the little metal clips, pull the line off of the nipples, and poke something through it, like a piece of wire, to see if there is actually a pill inside, or if it's missing.

Last edited by lastsnare; 11-04-2012 at 10:35 PM.
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Old 11-04-2012, 10:47 PM   #21
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BCS may be bad. Look on here how to test it with a battery. No CELs?
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Old 11-04-2012, 10:53 PM   #22
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Yeah a bad bcs would though a cel, a un pluged bcs would throw a cell. Having the wastegate plumbed directly to the intake with no bcs in there might throw one for failing to reach the boost target. Having an IAM of 0 due to a lot of knock would make it target wg pressure but would reset the iam to 8 after pulling the battery irrc.
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Old 11-04-2012, 11:19 PM   #23
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Quote:
Originally Posted by Badler View Post
BCS may be bad. Look on here how to test it with a battery. No CELs?

No CEL's no Knock. Testing the BCS requires stripping the wires and I dont really feel comfortable doing that..., Unless im not reading the correct way to test?
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Old 11-05-2012, 05:22 AM   #24
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What's up with the 5" exhaust? Does the car have a stock down pipe? What about the butt dyno? Does it feel like it pulls hard or is it a wet noodle?
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Old 11-05-2012, 06:58 AM   #25
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Quote:
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What's up with the 5" exhaust? Does the car have a stock down pipe? What about the butt dyno? Does it feel like it pulls hard or is it a wet noodle?
It's not gonna be all that slow at 6psi boost. My car is under 6psi boost almost everywhere accept full throttle accel.

Quote:
What kind of boost gauge do you have and when you let off the gas what vacuum does it go to?
Some gauges are much cheaper than others. If it's an electronic gauge it could also have a delay so if your not in say 3rd or 4th and WOT for more than a few seconds at above 3krpm you might not see a high boost.
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