BOOST FLUTTER? Blowing my mind please help!!!!!
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This is a discussion on BOOST FLUTTER? Blowing my mind please help!!!!! within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; 02 wrx wagon 85xxx TBE up pipe cobb stage 2 flash Car drove great for about 2-3000 miles after all ...

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    BOOST issue? Blowing my mind please help!!!!!

    02 wrx wagon
    85xxx
    TBE
    up pipe
    cobb stage 2 flash

    Car drove great for about 2-3000 miles after all the mods.
    here is the prob. Maybe about 2000 miles ago i was on the high way and doing about 80 i put my foot down a little or all the way it dosnt matter, and the boost creeps up to 1.1 (around ther is pretty normal) then goes down to .05, then back up to 1.2ish then, then back down then back up then back down, then up, then down then up then...well you get the point. this continues for how ever long i am on the gas. Sometimes while its bouncing like that, it will boost crazy high, like 1.3-1.4, but it could just be the analog factory gauge not able to stop on a dime like that.you can feel the car pull hard then soft, then hard then soft. some times if i hit the gas hard or soft it boosts fine and steady. i would say its 50/50.
    so i have been playing around with it and it is 3rd-4th-and 5th only. cant get it to do it in 1st or 2nd. i do belive some days is worse then other. meaning i will drive 50-100 miles on the high way and it may do it once if at all. then i will drive the same miles a couple days later and it will do it 50% of the time.

    Here is what i have done:
    First check all my hoses for leaks found nothing and have checked like 10 times. plus if it was a leak. it would be a constant problem all the time in all gears...right?
    i put the car in test mode and cleaned the solenoid with elec part cleaner.

    Other then that i dont know what else to do. i dont know anyone else with this car so i cant swap the solenoid out. i have read about it happening to 2 other people but they dont update the thread when and if they fixed hit. its killing me.
    any ideas?
    Last edited by pittielove; 02-01-2011 at 04:19 PM.

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  3. #2
    Registered User EvoEatr's Avatar
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    Quote Originally Posted by pittielove View Post
    02 wrx wagon
    85xxx
    TBE
    up pipe
    cobb stage 2 flash

    Car drove great for about 2-3000 miles after all the mods.
    here is the prob. Maybe about 2000 miles ago i was on the high way and doing about 80 i put my foot down a little or all the way it dosnt matter, and the boost creeps up to 1.1 (around ther is pretty normal) then goes down to .05, then back up to 1.2ish then, then back down then back up then back down, then up, then down then up then...well you get the point. this continues for how ever long i am on the gas. Sometimes while its bouncing like that, it will boost crazy high, like 1.3-1.4, but it could just be the analog factory gauge not able to stop on a dime like that.you can feel the car pull hard then soft, then hard then soft. some times if i hit the gas hard or soft it boosts fine and steady. i would say its 50/50.
    so i have been playing around with it and it is 3rd-4th-and 5th only. cant get it to do it in 1st or 2nd. i do belive some days is worse then other. meaning i will drive 50-100 miles on the high way and it may do it once if at all. then i will drive the same miles a couple days later and it will do it 50% of the time.

    Here is what i have done:
    First check all my hoses for leaks found nothing and have checked like 10 times. plus if it was a leak. it would be a constant problem all the time in all gears...right?
    i put the car in test mode and cleaned the solenoid with elec part cleaner.

    Other then that i dont know what else to do. i dont know anyone else with this car so i cant swap the solenoid out. i have read about it happening to 2 other people but they dont update the thread when and if they fixed hit. its killing me.
    any ideas?
    I am assuming you are referring to the wastegate solenoid as the the solenoid you cleaned? Is the check engine light on? Does if feel like the car misfires at all under load? Are you sure the clutch isnt slipping at all? Do you still have the brass restrictor pill installed? It kind of sounds like a wastegate problem. You said your 100% sure you dont have a pre turbo exhaust leak or boost leak anywhere?

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    Yes the waste gate solenoid.
    no cel
    no misfires
    and i forgot to mention i bought the car with a busted clutch so i replace with an oen clutch and act streetlight fly wheel. so the clutch has about 4000 on it. so its not that.
    check for leaks almost every day since it started. pill is still there. if it was a leak wouldnt it be in all gears not just the high gears. plus when i did work on the car recently (cleaning the solenoid) i re-set the ecu and it ran perfect for the first 100 miles or so.
    one last note, it seems to happen on longer trips when the car is really warm rather then like a quick 2 exit trip on the high way

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    Registered User EvoEatr's Avatar
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    Man this is the kind of place a decent scanner would be useful. You could view tons of engine parameters and possibly see where something is going on. Did anyone ever adjust the wastegate?

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    no on the adjusting of the wastegate. do you think thats it?
    i have read a couple threads on how to do that but i never read why they do it. which way do i turn it. how many turns. does any one have the a link off hand to point me in the right direction?

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    Registered User EvoEatr's Avatar
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    Quote Originally Posted by pittielove View Post
    no on the adjusting of the wastegate. do you think thats it?
    i have read a couple threads on how to do that but i never read why they do it. which way do i turn it. how many turns. does any one have the a link off hand to point me in the right direction?

    Almost always if the wastegate solenoid is at fault the check engine light will pop on. I think the wastegate is a possible issue. not saying thats it, as you know its pretty hard to accurately diag. a car online fore I cant touch or see it... I have heard of the wastegate arm adjustment causing flutter when using mods such as a catless downpipe... take a peek here, might be worth a read... Wastegate actuator arm adjustment - NASIOC

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    Moderator Donkey's Avatar
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    It's know as "boost oscillations". Either the wastgate duty cycle needs adjusted,the WGDC compensation per IAT tables or the wastegate arm. Call Cobb,as this issue has 100% to do with going Stage 2 with their EM product. There is at least 5-10 posts/threads a week on this common problem.
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    true about the 5-10 posts a week. but no one every follows up on how and if they fix it.
    on the thread about how to adjust the arm on this site someone with this same problem, mentions the position of the bend in the arm and how it should be lined up a certain way with the ...fender? or something. problem is he isnt very clear on which way the bend should be. any one know that brain buster. he said he had oscillations for a while because the bend in the ar was off from where is should have been. said he turned the arm "not the part with the c-clip" until it was back to "factory setting " and it was fine. problem is i dont know where that is. guess i could jut play with it for a bit.

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    Moderator Donkey's Avatar
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    My guess is if it ran fine for 2k-3k miles and now is having a problem it is the WGDC compensation per IAT tables. This is wastegate duty cycle compensation that is dependent on ambient temps (or what the IAT sensor is reading). This is an adjustment that has to be made in the ROM mapping.
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    can you explain what you just said a bit more?

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    Moderator Donkey's Avatar
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    There are compensation the ECU makes for different situations IE: altitude,intake temps



    My guess is one of those compensations needs to be adjusted. Mainly the temperature compensation. It's impossible for one generic map (Cobb Stage 2) to be able to work perfect on every single car especially when your talking about temp compensations.
    Last edited by Donkey; 02-03-2011 at 06:59 AM.
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    wastegate actuator, throttle posistion sensor, or the knock sensor, i literally just had this same problem

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    thank you for very specific answers. do you have a suggestion on where to start?
    i adjusted the wastegate arm 1 full turn (2 half turns) reset ECU and that didnt help. i say this because the arm was very rusty and brittle. which leads me to thin the whole thing is in bad shape.
    what gets me is why only in high gears?
    do you know which one it was? how did you get to those conclusions?

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    i took it to a mechanic i know well, what happens is if its your actuator the arm with let out prematurely under higher boost causing boost flutter, the tps and knock sensor have to do with the car being fed the wrong reading under acceleration causing flucuation in rpms/boost etc.... id seriously just take it to a local mechanic, the sensors are a pretty easy fix but if you dont fix them soon they can start causing other problems, if its the actuator you could just do it yourself, both parts are cheap under 200$

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