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Old 11-06-2020, 10:15 PM   #1
AdamRR
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Join Date: Oct 2020
Default Boost oscillation.

This is for a 2003 wrx. The only post with a follow up I've found were the boost oscillation was fixed was a waste gate being too tight and loosened with the actuator arm half a turn - full turn and the problem solved. Several other posts suggested this same fix but there is never a follow up. I tried this with half a turn and road testing all the way to two full turns and no luck the only thing this did was increase my spool up time. The car was stage 2 with a pro tune (boost oscillation still existed. It's just irritating me now) but I installed the stock downpipe and an spt smog exempt intake as well as went back to the stock tune and unmarried my Cobb AP to pass smog and I plan to keep it stock as long as this motor lasts. The only mods still installed are the cat back exhaust, Cobb electronic boost controller, a decatted up pipe, perrin turbo inlet and high flow fuel pump. Vaccume lines connecting to the boost controller are all new. My next move is a new restrictor pill? I can ease into target boost and it holds solid but when I go wide open throttle and let it spool up on its own. It jumps to 15psi and back down to 10 and repeats until you let off. 3rd gear will hit target boost sometimes WOT and have no issue but 4th and 5th are guaranteed. Another post suggested my waste gate could be failing? Hoping to get some answers before I drop anymore money into this motor as my end game is a swap and I've already put the cost of a nice ej207 into new tumbler valve motors + labor and stock parts for smog. Any suggestions and links are aporeciated
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Last edited by AdamRR; 11-06-2020 at 11:07 PM.
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Old 11-12-2020, 01:36 AM   #2
SlammedSix
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Location: 07 STi/ 08 STi/ 15 STi
Default

I had a weird boost oscillation issue on my Forester XT, turned out to be my Turbo. It was original to the car with like 150k miles
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Old 11-14-2020, 08:34 AM   #3
AdamRR
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Default

Ty for the reply. the turbo is original 212k miles. I was recently given a brand new vf43 for free but turns out it's a Chinese knock-off he bought on eBay and couldn't resell. It's obviously not legit but the turbine feels solid. any thoughts about it being better than the OEM with all the miles? should I slam dunk it in the scrap bin at my shop? rebuild my OEM or just eat the cost of a proper upgrade? could the electronic boost controller be asking for a higher target boost and conflicting with the stock ECU tune? my tuner (snail performance) charged me 1500 for an up-pipe install and the tune also they were very rude about questions I had after they were paid. I feel as tho they took advantage of me as I'm from way out of town 5hr one-way trip. id prefer to cut ties with them.
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Old 11-14-2020, 11:37 AM   #4
SlammedSix
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Quote:
Originally Posted by AdamRR View Post
Ty for the reply. the turbo is original 212k miles. I was recently given a brand new vf43 for free but turns out it's a Chinese knock-off he bought on eBay and couldn't resell. It's obviously not legit but the turbine feels solid. any thoughts about it being better than the OEM with all the miles? should I slam dunk it in the scrap bin at my shop? rebuild my OEM or just eat the cost of a proper upgrade? could the electronic boost controller be asking for a higher target boost and conflicting with the stock ECU tune? my tuner (snail performance) charged me 1500 for an up-pipe install and the tune also they were very rude about questions I had after they were paid. I feel as tho they took advantage of me as I'm from way out of town 5hr one-way trip. id prefer to cut ties with them.
I used an ebay VF39/VF43/VF48 equivalent turbo. Worked fine for me for a while, ended up selling the car with it.
So with the car back to stock the oscillating is still occurring?
To eliminate the possibility of the electronic boost controller or tune. I would use a manual boost controller just to see if the car still oscillates. You can make a generic one for like 5 bucks at Lowes or Home Depot
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Old 11-15-2020, 10:50 PM   #5
AdamRR
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ahhh interesting I will look into that. my tuner took my stock boost solenoid and i did not know it was that easy. ty for the tip.
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Old 11-25-2020, 07:56 PM   #6
fastfamilywgn
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I had fairly severe boost oscillation when I first bought my 02 way back (30k miles/2006) It was under warranty and the dealer changed a lot of parts without fixing it. I ended up purchasing a replacement stock boost control solenoid since they wouldn't try that. It fixed the problem.

It would oscillate boost even at 1/3 throttle in 3rd gear. Got pretty violent at WOT. I've never had a boost gauge but did use an ODB-II monitor that showed me boost oscillation from 8 to 14 psi.

Trying a manual boost controller is a good idea. I never tried that.
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