Wrx stays in vacuum??
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This is a discussion on Wrx stays in vacuum?? within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; Just got finished putting on the intake manifold on my 06 wrx. I had to replace the turbo inlet and ...

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    Wrx stays in vacuum??

    Just got finished putting on the intake manifold on my 06 wrx. I had to replace the turbo inlet and a pcv hose. Went for a test drive and the car is staying in vacuum. Cruising at max throttle reads -5.9psi steadily. It also is really hard to start, it takes some cranking over and pressing of the throttle but once it starts it idles and revs just fine. Some things that seem suspect:

    -turbo isnt making any spooling noises at all. Its a td06 18g. I plan on removing DP or inlet to test the spindle. It seemed fine when i had the intake off.
    - i forgot the gas cap was loose and it rained outside. Im not sure if any water got into the tank but it was at 1/4 and i filled it up and it made no difference at all.
    - soke water got into my intake ports from the rain but the valves were shut and no water appeared to have entered the cylinders. However if it did maybe it fouled out my spark plugs and thats my power loss cause?
    - lastly, i think i snapped one of the throttle body bolts. I was tightening it and it was tight then it just let go. I left it in there and didnt try to unscrew it yet. I dont think one busted throttle body bolt would cause a constant vacuum condition though.

    So thats everything, let me know please what any of you guys think it could be. She ran like a champ before, only reason i took off the intake was to fix a leaking broke pcv tube and the turbo inlet and now this is happening.

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    Registered User mustwarnorcas's Avatar
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    Did you hook up all the vacuum lines properly and ensure you didn't knock one off while working?
    "If the power increases, then I have to spend more money on gas" - Takumi Fujiwara

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    Quote Originally Posted by mustwarnorcas View Post
    Did you hook up all the vacuum lines properly and ensure you didn't knock one off while working?
    Yes i keep checking them because im paranoid about missing one. Im sure theyre all connected properly. The car is so damn slow its worrying

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            MainFrame's Avatar
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    I would look for a leak.. somewhere between the intake, and the heads... probably a big one. (check TB->TMIC coupler)

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    Quote Originally Posted by MainFrame View Post
    I would look for a leak.. somewhere between the intake, and the heads... probably a big one. (check TB->TMIC coupler)
    I inspected the coupler while it was off it seemed good. I plan on doing a pre turbo pressure test to rule out a boost leak

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    Thinking in the realm of gas, maybe its the fuel pump? There was no air issues before i did the repairs. So its got to be a fuel or turbk problem. If the fuel is being extremely limited how could i tell? Is a fuel pressure gauge easy to install?

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    lit fam XJman's Avatar
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    You would be misfiring like crazy. If you are making zero boost and only vacuum I would lean more towards a leak and less to fuel.

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    Quote Originally Posted by XJman View Post
    You would be misfiring like crazy. If you are making zero boost and only vacuum I would lean more towards a leak and less to fuel.

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    Okay. But arent symptoms of a failing fuel pump hard starting, bogging, and decreased performance? The only thing i can think of off the top of my head would be the snapped throttle body bolt. But that doesnt seem like it would cause a big enough leak to cause this. I guess ill only know for sure once i do a pressure test. The car is parked for a month currently as im away from it. @

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    lit fam XJman's Avatar
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    It could. All of those symptoms could be massive intake and boost leaks too.

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            MainFrame's Avatar
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    Quote Originally Posted by dtodt13 View Post
    Thinking in the realm of gas, maybe its the fuel pump? There was no air issues before i did the repairs. So its got to be a fuel or turbk problem. If the fuel is being extremely limited how could i tell? Is a fuel pressure gauge easy to install?

    Wait.. it had this issue going on prior to the work you did on it? I thought you were saying you did all this work on the intake system, then when you put it back together it didn't run right anymore (which would point to something having gone back together wrong). If it had the problem before that opens it up to other possible causes.

    I would still pressure test the system though.. we see A LOT of people with intake leaks causing issues, and very few with fueling problems.


    As far as installing a fuel pressure gauge, it's not too bad.. and they're relatively inexpensive. You could just get the gauge, and two fittings. Take a T fitting that the gauge can screw into, put a short section of fuel line on one of the other ends of the fitting, pop on, disconnect the feed line up stream from the FPR, pop one the line from the T onto the rail or whatever you disconnected the feed line from, then stick the disconnected feed line on the the remaining end of the fitting.


    Another possibility would be a pre turbo exhaust leak, but it would have to be pretty big, and you would probably hear it.. kind of like a tapping sound.

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    Quote Originally Posted by MainFrame View Post
    Wait.. it had this issue going on prior to the work you did on it? I thought you were saying you did all this work on the intake system, then when you put it back together it didn't run right anymore (which would point to something having gone back together wrong). If it had the problem before that opens it up to other possible causes.

    I would still pressure test the system though.. we see A LOT of people with intake leaks causing issues, and very few with fueling problems.


    As far as installing a fuel pressure gauge, it's not too bad.. and they're relatively inexpensive. You could just get the gauge, and two fittings. Take a T fitting that the gauge can screw into, put a short section of fuel line on one of the other ends of the fitting, pop on, disconnect the feed line up stream from the FPR, pop one the line from the T onto the rail or whatever you disconnected the feed line from, then stick the disconnected feed line on the the remaining end of the fitting.


    Another possibility would be a pre turbo exhaust leak, but it would have to be pretty big, and you would probably hear it.. kind of like a tapping sound.
    Yes it ran fine before the work i did. Im certain its together properly, all electrical and tube connections with clamps and torque specs. What do you mean by tapping sound? Pre exhaust leak being the exhaust manifold and up pipe? Because there is a slight tapping sound that im pretty sure wasnt there before i did the work. Its like a slight tick that matches the rpms. Most prominent when its starting and turning off. But then again how could i develop a leak that fast when the car was just sitting there.

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    Okay i took it around the block and looked at all my accessport parameters. Something that seemed really suspect was that fuel pump duty cycle stayed at 33%. Didn't go any higher or lower. Usually when I'm at full throttle itll hit 100%. I also tried intently to listen to the fuel pump when turning the key as well as when idling and i could nkt hear any whining from its location

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    Water.....sometimes waves rqjoe's Avatar
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    Quote Originally Posted by dtodt13 View Post
    - lastly, i think i snapped one of the throttle body bolts. I was tightening it and it was tight then it just let go. I left it in there and didnt try to unscrew it yet. I dont think one busted throttle body bolt would cause a constant vacuum condition though.
    I think it is this.

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    Quote Originally Posted by rqjoe View Post
    I think it is this.
    Idk man. 3 bolts would still provide a pretty tight seal. For now thats ruled out until i can do a boost test. A leak that big in that area would make a lotnof noise and i cant here anything unusual as its driving. The car drives and sounds just fine its as if there isnt even a turbo on it.
    Last edited by dtodt13; 04-21-2017 at 07:53 AM.

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    Quote Originally Posted by dtodt13 View Post
    Okay i took it around the block and looked at all my accessport parameters. Something that seemed really suspect was that fuel pump duty cycle stayed at 33%. Didn't go any higher or lower. Usually when I'm at full throttle itll hit 100%. I also tried intently to listen to the fuel pump when turning the key as well as when idling and i could nkt hear any whining from its location

    If you're not building boost you're not going to hit load cells that require 100% fuel pump duty cycle. You can replace the fuel pump if you want, but I doubt that will change anything. I would say at least a 90% chance the problem is directly related to the stuff you messed with when you were working on it. There's no reason anything else on the car would suddenly encounter a failure while you were working on the intake stuff.




    Quote Originally Posted by dtodt13 View Post
    Idk man. 3 bolts would still provide a pretty tight seal. For now thats ruled out until i can do a boost test. A leak that big in that area would make a lotnof noise and i cant here anything unusual as its driving. The car drives and sounds just fine its as if there isnt even a turbo on it.

    My car ran and drove fine.. there didn't seem to be a problem at all, but I went ahead and did a boost leak test before loading it on the dyno for another tune.... We uncovered SEVEN leaks, two of them pretty substantial. You couldn't hear a thing when you were driving, but as soon as we pressurized the system it started leaking everywhere.

    Did you replace all the gaskets when you put it back together? I had a leak both at my throttle body to manifold (even though I had all the bolts in and torques down), and my BPV gasket. The BPV gasket was leaking a ton, and it was torqued down correctly as well. The rest of the leaks were at various FMIC couplings.

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