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Discussion Starter · #1 ·
Well since the car has been turbo it only boosted around 4lbs. I chalked it up to the wastegate being messed up. The arm and bracket had to be modded in order to fit. No problem because through either t's or MBC i've been able to up it to the desired 6.5-7lbs. So here is the thing, I threw on a cheap ebay mbc and set it up. I got a perfect 7lbs and it held steady right to redline. No spiking or anything. But now I'm back down to 4lbs? Everything is still hooked up the same, what the heck happened. I am getting a little jumpiness if that makes sense. I think maybe an IC pipe is loose. I don't know why I'm writing this because I know all your answers already.

1. get rid of the crappy ebay MBC replace with something better (hallman etc...)
2. do a pressure test on the IC pipes
3. stop wasting time and posting crap you already know the aswers to on g20 just because your bored at work!
 

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drunken master
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it does sound like a bit of a leak or tht the wastgate needs atention.
i have turbo xs manual controller nd it is very consistant but unless the controller is moveing buy its self i dout that it is the problem.

i hve helped freind with a simular problem. but he has a s14 with s15 engine we found later that the wast gate was fualty then relised that the s15 had a recall on the waste gate are bulliton are something like that so we changed it and he says he is running better than ever
 

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Discussion Starter · #4 ·
Well I'm bringing this one back!!! I recently got fed up with my cars performance and decided to really start to tackke the problem. So yesterday I pulled the line off of the wastegate and capped the other end! That should cause infinite boost right? Well not on my car. I got 6-7psi only! I checked the wastegate actuator and it's nice and tight. I can move it with my hand but it takes some muscle to do it. Then when you let the rod go it snaps back! I believe that is proper operation but I'm not sure. Unless it's not seating properly. I'm going to re route and change my vac lines, get new t's, and pressure test the system. Anyone have any thoughts or tips for me? Is there any way I can check to see if my BOV is functioning correctly? I do hear the turbo spool and the BOV but niether seem that loud anymore. Is my turbo shot? What are the signs of that? I have no oil in the IC pipes and blow zero smoke. Car has 155k miles and 90k miles on the turbo.
 

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shenanigans
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I know that it depends on where you run your wastegate signal line from, but it should be greater than 4psi even without the MBC. All dets turbos come with either a 7 or 9 psi wastegate. You cant go lower than that. So keep that in mind as well
 

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Discussion Starter · #6 ·
well I'm running 6 psi with no line hooked up! There is no boost source going to the wastegate there for it should boost to a 1,000,000 psi (slight exageration). This isn't a DET turbo its a garret gt28R. I guess it's the same as an s15 turbo though. Any way I can check if my BOV is working or if it's just pushing the boost air back into my intake?
 

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Discussion Starter · #8 ·
well I found one problem. The line I was using for the wastegate was not a strong enough source! I then hooked it up to the FPR line which I know is a strong enough source and that's when I found my new problem which has been my problem all along! My wastegate is now squealing like a baby pig!!! Sounds like air escaping out of a balloon when you stretch the sides!

So what does all this mean! I have absolutely no idea! Thoughts please!
 

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Discussion Starter · #10 ·
OK so now what do I do? Any way to swap it out with out removing the entire turbo from the car? Like maybe cut the rod and thread it then use some sort of turn buckle on a new one? Am I actually leaking air? Because if I was wouldn't that act more like a boost controller and make me boost higher instead of lower? Should I remove the wastegate line from the FPR line since is leaking?
 

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Prince of Joy
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This is going to be one of those handholding threads, isnt it ;)

Get your hands dirty, man. The wastegate actuator is more than likely your problem. Yes you will have to pull the turbo and manifold off the car. Yes it sucks. If the actuator is leaking under boost, then obviously you dont want anything connected to it. Last thing you want is a vac leak on your fuel pressure signal and blow up your car. Thats the reason why I never put anything on the FPR line other than the FPR.


- Greg -
 

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Discussion Starter · #12 ·
This is going to be one of those handholding threads, isnt it
Yeah it is!!!

I will take it off the FPR line. I don't have the tools in order to remove it from the car nor the money to have someone do it so I guess I'm just fawked! The actuator is leaking under vacuum! The annoying screech is at idle! Man this sucks! With 90k on the turbo if I do go through all of this maybe I should just look into getting a new one of those too!

edit: I would have no problem trying to tackle this myself except this is my only vehicle. I am a single dad and have to drive 100+ miles aday. Can't afford any down time.
 

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Discussion Starter · #13 ·
bent the wastegate bracket over 1/4"! Car is freakin amazing! full boost every gear before 3k rpm's! I love my car again. It has never been this fast! Wastegate still making the noise but it's definately working right. Thanks everyone!
 

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drunken master
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I hope you are not over boosting. you bent a wast gate to much and it can chatter cuase of the angle but the waste gate will not open enogh when it needs to. oh yes car will spool faster and hit harder but where is the boost on a 3rd gear pull to red line and where are your a/f's.
i would hate to see you happy as hell injoying more power than your fuel suports. but in the end i hope you are with in fuel range and happy cuase the car did not run right before. Please take time and check cuase i do not want to see a blowen engine post .

keep in mind in my post that i saiad the wastgate may need atention meaning it is not a good wast gate are not adjusted correct. I by all means did not recomend bending it. i recomended checking it nd makeing a correct repare
 

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Discussion Starter · #15 ·
I didn't bend the wastegate. I bent the bracket that it sits on. I checked my boost yesterday. I've been feathering it because I thought I might be overboosting. It goes straight to 5psi (might be 6 my gauge isn't very accurate) in every gear. Hits it by 3k rpms and just stops there all the way to 6k rpms (i don't red line her ever). The car was dyno tuned a few years ago at 6.5psi. I would assume that half a pound less I should still be good. I'm going to change the plugs this weekend and see what they look like. I don't have a wideband so can't check th A/F's.

A gt28r on a gtir manifold (down facing), the wastegate bracket needs to be modified. Mine was but apparently not modded correctly. So all I did was fix the bracket. It must be working correctly because boost hits a brick wall right at 5-6psi. Never goes above it! Car sounds great, no pinging, knocking or anything.

You got me all scared now!
 

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Prince of Joy
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Sounds like before you fixed it the bracket was bent and the actuator was bound open and couldnt close fully - hence the low boost levels. If it was sticky and binding then it would be kind of random performance. I dont see a big deal in bending the bracket as long as the end result is an actuator that moves freely and doesnt bind. It's certainly a lot better than removing the entire manifold and turbo to replace the actuator.

The other thing you can do is test the actuator in its current location with compressed air. Make sure it opens and closes fully and without restriction and you should be good. The real thing you want to avoid is it sticking closed, not open.


- Greg -
 

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Discussion Starter · #17 ·
The bracket was fabbed out of 1/4" aluminum. It's not the regular bracket. It was holding the flapper open. It seems to be working perfectly now. The wastgate is making the pig noise but only under vacuum. So I put the MBC back on and turned it all the way down. It maybe gave me 1/2 a psi at most. I more using it like a check valve instead of a MBC. End result is bout 5 more hp (but dyno) and no more pig squeal at idle! She's running like a champ! I'm not looking forward to seeing the gas mileage though. No wonder I was able to get 32mpg with a turbo.
 

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drunken master
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as long as your not over boosting. than that is cool i suposed the braket had bent over time and you fixed it by bending it back. oviusly you know now the power loses of a wast gate stuck open. i rell y did just want to clarify to make sure you were safe cuase i have had my car over boost befor and it was scary fast at first. i was not safe to be makeing that type of power i was so i found the problem and corrected it.

hopefully your car is tuned well .

A turbo i recently installed for some one hd the wast gate stuck open and was chattery and i spoted this as we were bying the turbo used from some one. given tht their car never made real power and their responce had to be ass. but turbo was in top knotch condition so i was set on droping the price on it for the found problem and in the end got them a grest deal on a ner perfect turbo
 

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When I had my boost problem, 1 had two problems :my bov was leaking, and I had it hooked up to the brake booster line, which can't hold much boost. So I was only boosting 5psi, even with a boost controller. Leak problems can be a bitch to fix, especially when you don't know it's a leak. Glad you figured out what it is at least.
 

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drunken master
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dont feel bad koojo lots of prts i have installed over the yers used leeaked and i had to fix them bov's beeing the most replaced part. i when i get my new blow of valve i do not even wnt to sell it even though it workes good ror me i m keeping it cuase i have fond loads of bov's leak on different set ups. im reall not try to bs around and sell my flawless type s eithger
 
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