Low Boost Issues on 2004 WRX - Experts help needed here - Page 2
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This is a discussion on Low Boost Issues on 2004 WRX - Experts help needed here within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; My bet is the car is possibly detonating and the ECU is pulling boost and timing to save the motor. ...

  1. #16
    Moderator Donkey's Avatar
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    My bet is the car is possibly detonating and the ECU is pulling boost and timing to save the motor. The actuator doesn't just "pop" open at the preset level. It will slowly will open and should be completely open by the preset level. A 7psi actuator will start to crack open around 3-4 psi.
    Last edited by Donkey; 03-11-2010 at 04:09 PM.
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  3. #17
    Admiral Ackbar the 1st mycologist's Avatar
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    Quote Originally Posted by Donkey View Post
    My bet is the car is possibly detonating and the ECU is pulling boost and timing to save the motor. The actuator doesn't just "pop" open at the preset level. It will slowly will open and should be completely open by the preset level. A 7psi actuator will start to crack open around 3-4 psi.
    I was kind of wondering about that but something I read made it seem that that was the definition of "preset". It still should equilibrate to 7psi on the car though. I still would wager that the WGDC is pegged at 100%. I would still fix it even if something else is wrong.
    Last edited by mycologist; 03-11-2010 at 04:46 PM.
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  4. #18
    Admiral Ackbar the 1st mycologist's Avatar
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    Just a sanity check, it does cause problems commonly on the older cars, we probably just don't see it much yet:

    Scoobypedia | Trusted knowledge for everything Subaru | Knowledge / Boost Related Issues
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  5. #19
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    Quote Originally Posted by Donkey View Post
    My bet is the car is possibly detonating and the ECU is pulling boost and timing to save the motor. The actuator doesn't just "pop" open at the preset level. It will slowly will open and should be completely open by the preset level. A 7psi actuator will start to crack open around 3-4 psi.
    Okay, but if detonation was my problem would it just limit the boost and timing without trowing a CEL or att some point miss and rattle a little? The engine is running smooth..

    Hmm.. well ive obtained a acutator from a friend now, a brand new one actually, with an adjustable arm. Im going to pull my one off and then compare these two with compressed air connected before i start working with the new one.

    I will have to fabricate a bracket to fit this new one but that will not be a big problem i think.

    Will post updates within 24 hours.

  6. #20
    Admiral Ackbar the 1st mycologist's Avatar
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    I heard mine rattle when I had an inlet leak - IAM was only dropped to 12 and it wasn't pulling boost yet.

    Just so you know though, we are all taking a bit of a blind shot without the logs. Hope this wastegate isn't a waste of your time .... (then again driving 6 hours only to find out you need to do this then come back would also be a big waste).
    "From a little spark may burst a mighty flame." - Dante
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  7. #21
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    Quote Originally Posted by mycologist View Post
    I heard mine rattle when I had an inlet leak - IAM was only dropped to 12 and it wasn't pulling boost yet.

    Just so you know though, we are all taking a bit of a blind shot without the logs. Hope this wastegate isn't a waste of your time .... (then again driving 6 hours only to find out you need to do this then come back would also be a big waste).
    Ok, yea i know but it feels like that i should be doing this. Its not that much of work. Think it's alot easier than removing the intercooler and reinstalling that piece.

    Will be looking into logging the car if i cant sort this out this weekend..

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    A little update.

    Unbolted my acutator from the turbo and putted it next to the new one on the table. i compared those two with compressed air and it was exactly the same strength in both.

    Fabricated a bracket and installed the new one in the car, had the arm adjusted so it was the same lenght as the old one.

    Hooked up a clean vac-line from the compressor housing to the acutator, had it for a spin and same boost as before achived..0,3 bar.

    Since the new one was adjustable i shortened the arm like 5mm. Had to pull a little harder to get the locker in. Test drove.. Same boost, 0,3 bar. Then i shortened it another 7 mm (arm is totaly 12mm shorter than the old wastegate now) and had to pull it even harder to get it on. But guess what.. Same boost..

    How is this possible? The ecu cant do anything in some way to "release" pressure as far as i know. This is 100% mecanical now.

    Will run the vac-lines as they should be tomorrow and see if it hits 0,7 as before with the solenoid. Will pull the downpipe down too.
    Last edited by Myzkoo; 03-13-2010 at 04:55 PM.

  9. #23
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    Quote Originally Posted by Myzkoo View Post
    A little update.

    Unbolted my acutator from the turbo and putted it next to the new one on the table. i compared those two with compressed air and it was exactly the same strength in both.

    Fabricated a bracket and installed the new one in the car, had the arm adjusted so it was the same lenght as the old one.

    Hooked up a clean vac-line from the compressor housing to the acutator, had it for a spin and same boost as before achived..0,3 bar.

    Since the new one was adjustable i shortened the arm like 5mm. Had to pull a little harder to get the locker in. Test drove.. Same boost, 0,3 bar. Then i shortened it another 7 mm (arm is totaly 12mm shorter than the old wastegate now) and had to pull it even harder to get it on. But guess what.. Same boost..

    How is this possible? The ecu cant do anything in some way to "release" pressure as far as i know. This is 100% mecanical now.

    Will run the vac-lines as they should be tomorrow and see if it hits 0,7 as before with the solenoid. Will pull the downpipe down too.
    It would seem now that your boost gauge is not working correctly. I would be hesitant to hook it all back up with that much pretension if you aren't 100% confident in the gauge as you could have bad boost spiking or overboost.
    "From a little spark may burst a mighty flame." - Dante
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  10. #24
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    Quote Originally Posted by mycologist View Post
    It would seem now that your boost gauge is not working correctly. I would be hesitant to hook it all back up with that much pretension if you aren't 100% confident in the gauge as you could have bad boost spiking or overboost.
    It is definitly not over boosting or spiking, runns like a N/A car :P

  11. #25
    Admiral Ackbar the 1st mycologist's Avatar
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    Well dang. When I adjusted my arm just a couple turns (threads) is good for ~ 1 PSI.

    Time to inspect the turbo itself and or get a log.
    "From a little spark may burst a mighty flame." - Dante
    "The stitch is lost unless the thread is knotted." - Italian proverb

  12. #26
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    Havent had any time for the car for the past few days. But today i hooked up all the vac-lines as they should be with the boost solenoid connected.

    The high-tension adjustment on the acutator is still there.

    And i could see that boost peaks at 1.05 bar (almost 1.1 bar). But its only for like a split second then it drops back to 0.6-0.7

    Will pull the dp down on monday or maybe tuesday.

    Will make an $1000 order from extremepsi.com tonight too
    Last edited by Myzkoo; 03-20-2010 at 10:40 AM.

  13. #27
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    Quote Originally Posted by Myzkoo View Post
    Havent had any time for the car for the past few days. But today i hooked up all the vac-lines as they should be with the boost solenoid connected.

    The high-tension adjustment on the acutator is still there.

    And i could see that boost peaks at 1.05 bar (almost 1.1 bar). But its only for like a split second then it drops back to 0.6-0.7

    Will pull the dp down on monday or maybe tuesday.

    Will make an $1000 order from extremepsi.com tonight too
    Bewildering - I'm very interested to hear what you find when you look at the flapper. Almost sounds like something is stuck in there.
    "From a little spark may burst a mighty flame." - Dante
    "The stitch is lost unless the thread is knotted." - Italian proverb

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    Problem still not solved.

    But managed to finally log the ecu with a diagnostic tool called AUTO-COM that i found at a local shop. Was able to log 3 minutes of driving. And one thing i noticed was that the intake pressure (i guess that this is the pressure measured from the map-sensor) was showing 2.55 bar while my boost gauge showed 1.0 bar, wich is max boost i can reach with this adjustable wastegate. I know that the map reads the atmospheric pressure to but its still like 1.55 bars of boost messured?

    So i borrowed my friends map-sensor but still got the same readings on from the ecu.

    Is this ok? Shouldnt the mapsensor be reading the same pressure as my boost gauge?

  15. #29
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    Quote Originally Posted by Myzkoo View Post
    Problem still not solved.

    But managed to finally log the ecu with a diagnostic tool called AUTO-COM that i found at a local shop. Was able to log 3 minutes of driving. And one thing i noticed was that the intake pressure (i guess that this is the pressure measured from the map-sensor) was showing 2.55 bar while my boost gauge showed 1.0 bar, wich is max boost i can reach with this adjustable wastegate. I know that the map reads the atmospheric pressure to but its still like 1.55 bars of boost messured?

    So i borrowed my friends map-sensor but still got the same readings on from the ecu.

    Is this ok? Shouldnt the mapsensor be reading the same pressure as my boost gauge?
    Quote Originally Posted by mycologist View Post
    It would seem now that your boost gauge is not working correctly. I would be hesitant to hook it all back up with that much pretension if you aren't 100% confident in the gauge as you could have bad boost spiking or overboost.
    The other way around. The boost gauge is supposed to match the manifold pressure. I would trust what you are seeing from the ECU and not your gauge or your butt dyno.

    I've been suspicious of the gauge all along especially when it showed no effect of changing the actuator tension. It also falsely indicated the previous spring being low.

    Sounds like you boost is a bit high now. Does it really not feel like it is hitting? Can you log the IAM or whether any knock correction is occurring or total timing?
    "From a little spark may burst a mighty flame." - Dante
    "The stitch is lost unless the thread is knotted." - Italian proverb

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    Quote Originally Posted by mycologist View Post
    The other way around. The boost gauge is supposed to match the manifold pressure. I would trust what you are seeing from the ECU and not your gauge or your butt dyno.

    I've been suspicious of the gauge all along especially when it showed no effect of changing the actuator tension. It also falsely indicated the previous spring being low.

    Sounds like you boost is a bit high now. Does it really not feel like it is hitting? Can you log the IAM or whether any knock correction is occurring or total timing?
    Hmm, well, i will have a look at my gauge, but something has to be wrong as the car feels alot slower. Will change back to the stock wastegate and log again and see what it reads.

    There was some kind of option in the software that showed knocksensor (i guess correction?). but it only showed on/off. And it was reading "off" all the time.

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