Bad boost fluctuations... I'm out of ideas, please help - Subaru WRX Forum
 
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#1 Old 03-29-2010, 10:10 PM
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Question Bad boost fluctuations... I'm out of ideas, please help

I have an '02 wrx that is experiencing horrible boost fluctuations and quite a large loss of power. It has about 65k miles on it and is completely stock except for a new bcs. The problem started a month or so ago and has only gotten worse. When I floor it, the car boosts up to about 14psi the drops to 9 or 10 then boosts back up to 14 then drops back down to 9 or 10. It just jumps back and forth, never holding at one pressure and you can definately feel it in the car. I have put in a new bcs, checked all my vacuum lines, and even changed swapped the complete turbo with wastegate for another stock td04 set up. I can also really feel a loss of power now that has gotten progressively worse even with the new turbo, it doesn't pull near like it used to. I am very puzzled as to what is causing the problem and frustrated so please help me out if you have any ideas. Thanks!
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#2 Old 03-29-2010, 11:26 PM
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Is it a manual boost controller or a replacement/upgrade electronic bcs? Either way I'm going to go with the bcs as the issue. If you have an aftermarket (upgraded)3-port ebcs, you'll need to get the car tuned for it.

If you just slapped a manual bcs on it, take it off. Our cars don't like mbc's.

If it's a replacement stock bcs did you reuse the existing vacuum lines that were on the original one? If you replaced them there is a small pill in one of the lines that controlls the boost coming off the compressor and to the bcs/wastegate. If that's not in there anymore you can have some boost issues. Now if you replaced with a 3-port bcs, then you should have removed the pill, and will need to get tuned.

-Chris
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#3 Old 03-30-2010, 12:44 PM
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Thanks for the info chris, I greatly appreciate it. I was experiencing the problem with the factory bcs so I replaced it with a perrin 3 port (not manual) and am still experiencing the same problem. I have tried the factory settings indicated on the instructions as well as taken the pill out of the line, put all new lines in, and tried the other settings that it indicated. The only thing I have not tried yet is a re-tune, is that what it needs to get back up and running normal? When I was having the problem and the original bcs was installed did it also need to be retuned... can the car get thrown out of tune?
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#4 Old 03-30-2010, 02:06 PM
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So the car was doing it before the new 3-port went on?

You still need to get tuned for the 3-port as it can cause you to overboost and cause other boost issues.

-Chris
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#5 Old 03-30-2010, 09:55 PM
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Well, the question is. Did you hook up the Perrin bcs in a slow responce (2 port) set-up or fast responce (3 port) set-up? It can do either. I used to own one and I got rid of it for a grimmspeed 3-port. If it is in a 2 port set-up. It pretty much runs like a stock oem bcs and it wouldn't be the bcs probably causing the issue IMHO. Do you have a tuner near by? If yes, have them check it out.

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#6 Old 03-31-2010, 03:34 PM
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The car was indeed experiencing the fluctuation problem before I put the new bcs on. My first thought was the factory solenoid went bad thats why I replaced it but it still does the same thing with the new one. I have ran the perrin on 2 port (slow resp) as well as the 3 port (fast resp) setting and either way the boost still jumps up and down. Could I have a problem with my ecu, possibly a crack in the tmic, or a bad bov? Im trying to eliminate all possibilities. Out where I live, there are very few tuners and none tuners that I would really trust with my car (due to many friends having bad experiences). I would have to drive the car about 3.5 hours up north to find a decent shop so im just trying everything I can think of before I resort to that.
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#7 Old 03-31-2010, 04:40 PM
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Well I guess the next, and least expensive step, would be grabbing some brake cleaner and spray around all your vacuum/boost lines with the car running. If you hear the car change sounds (stutter/different idle sounds) you've found a leak and it's sucking in the brake cleaner.

-Chris
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#8 Old 04-02-2010, 11:11 AM
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Thanks chris I will try that this weekend and let you know what happens
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#9 Old 04-02-2010, 12:06 PM
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check for a boost leak..my 02 had a crack in a vacuum line under the tmic
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#10 Old 09-02-2010, 08:52 PM
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I am having the exact same issue. !Cry! Did you find a solution to your problem Lovemywrx25? Was it a boost leak or something else? Thanks in advance for your help.
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#11 Old 09-02-2010, 09:05 PM
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I would suggest you try e-mailing him, seeing as how all 4 of his total posts are in this thread it's highly unlikely he's going to return to the thread

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#12 Old 09-03-2010, 08:58 AM
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If anyone in the future sees this post... use soapy water... not brake cleaner or any other solvent....

Not trying to step on toes Chris.

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#13 Old 09-09-2010, 11:35 PM
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For me it turned out to be the bcs. Bought a stock one off ebay. Took two minutes to switch out and the symptoms are gone.

Thanks pzr2874, I was gonna try the brake cleaner or something along those lines because it sounded straight forward and easy to do, but I was worried about how it would affect the hoses long term.
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#14 Old 09-10-2010, 12:08 AM
 
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Same problem, here's my solution :
boost spikes and fluctuation
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