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Old 03-04-2014, 08:50 PM   #1
car_freak85
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Join Date: Dec 2001
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Location: Cascadia
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EA63 , EA81T, EG33,
EJ205

Default 2002 WRX boost spike/oscillation (logs inside)

Long story short I replaced my shortblock and added a few bolt-on goodies at the same time. Ever since I've had this weird spiking/surging issue that I can't figure out.

GP Moto snorkus delete
Cosworth panel filter
Perrin after MAF hose
Perrin turbo inlet hose
Grimmspeed 8mm phenolic spacers
Cobb uppipe
All rubber hoses replaced with silicone, brass pill reinstalled
Perrin crank pulley
Exedy chromoly lightweight flywheel
(I now have a Stromung catback, but this problem was present beforehand)

Links to the logs are here:
https://drive.google.com/folderview?...U0&usp=sharing

Any ideas?
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Last edited by car_freak85; 03-06-2014 at 01:06 AM.
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Old 03-05-2014, 08:09 AM   #2
quazimoto
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Default

Did you reinstall the pill in the right line? What diameter silicone hose did you use?
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Old 03-05-2014, 10:44 AM   #3
IamGipper
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Location: Burnsville, MN
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2002 Impreza WRX
SRP Stage 2

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Check dat restrictor pill. It's in the rubber lines that go from the turbo to the EBCS. Same boost spike and oscillation thing was happening to mine. Ended up having to get a tune to completely fix the problem.
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Old 03-05-2014, 03:05 PM   #4
car_freak85
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Default

I'm pretty sure i got the pill in the correct line, as well as the little plastic male/male part. Maybe I should zip-tie the pill in place in the hose to make sure air isn't getting around it.

Not sure what the ID of the hoses are, it came in a universal kit from eBay. Probably 4 or 6mm for those lines, double zip-tied at both ends.

Last edited by car_freak85; 03-05-2014 at 07:15 PM.
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Old 03-14-2014, 09:02 PM   #5
car_freak85
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Bump for some insight...
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Old 03-14-2014, 09:22 PM   #6
AlexWRXbruh
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Quote:
Originally Posted by car_freak85 View Post
Bump for some insight...
shoulda got a GrimmSpeed bcs while you were at it...tune and your problems will be solved from there, but just my opinion/insight
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Old 03-15-2014, 01:26 AM   #7
Scoobiesdoobies
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OBP

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Cobb stage 2 requires the use of a different size restrictor pill for some applications.
I have the same spiking on my 2.5l and I havent adjusted the mhi actuator arm yet.
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Old 03-15-2014, 09:16 AM   #8
2gnt2wrx
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Quote:
Originally Posted by car_freak85 View Post
I'm pretty sure i got the pill in the correct line, as well as the little plastic male/male part. Maybe I should zip-tie the pill in place in the hose to make sure air isn't getting around it.

Not sure what the ID of the hoses are, it came in a universal kit from eBay. Probably 4 or 6mm for those lines, double zip-tied at both ends.
If you are talking about using zip ties to keep the restrictor pill in place, you most certainly used the wrong size hose. I believe Subaru sells the bcs hoses as a kit, or you may be able to find someone willing to sell theirs in the classifieds.

You do not need a 3 port bcs or any other bcs to get rid of the oscillation. Sometimes I think spending other peoples money is a natural reaction on this board.
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Old 03-15-2014, 11:01 AM   #9
Shiftace420
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Silver

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From reading the logs, what I can see is your Target Boost (13.6psi) is being overshot by a few PSI. During that time your WGDC was trying to adjust boost but had to drop it to almost 20WGDC to get it to start dropping.

Theory:
1) Your vacuum lines on your boost control system might be leaking or wrong size. A very small leak is all it takes, Your boost control relies on very precise sizing and pressure to accurately control boost. Your overshoot is likely a leak. Please get the right hoses and try again.

2) You may have put a "pre-load" on your wastegate and its not able to push the gate open with normal WGDC due to fact the spring pressure is not correct. (too tight). For your current boost levels, You should shoot for around 7psi wastegate pressure. Take the vac hose off the tee that goes to your BCS and plug it, the Tee and the hose side both need plug/cap. Take your warmed up car for a spin and in 3rd or 4th you do a pull. Watch the boost, It should rise to 7psi and hold. This is your mechanical boost setting. IF its too high then adjust a few turns and try again until you get your Target Mechanical Boost. Then put your hose and tee back together, reset your ecu and check your boosting. Higher Mechanical Boost settings are needed on some stage2 setups to achieve the full 16psi. RULE of THUMB: Wastegate Mechanical Pressure needs to be set at half the desired Target Boost of your tune. Stock = 13.6psi Target so 7psi is where it needs to be. After you adjust your Wastegate, disconnnect the battery to reset your ECU (and boost tables)

3) After you replaced hoses and set your Mechanical Pressure a different pill restrictor might be needed to correct your overshoot but.... I dont think that this is your issue im just adding it for more info for future readers.

4) Last, check your tune. (3 and 4 might be backwards but they sort of go together)

There is a really good right up about setting you boost up on the COBB site. Highly recommended and comes with pics and detailed instructions how to set these items.

https://cobbtuning.zendesk.com/hc/en...l-System-Works

Last edited by Shiftace420; 03-15-2014 at 11:30 AM. Reason: Giant Space Monkey Eats Lettuce
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Old 04-25-2014, 03:13 PM   #10
car_freak85
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EJ205

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I was finally able to swap back to new OEM hoses and, amazingly, the strange boosting is gone (reset the ECU as well).

I still don't get why the silicone hoses would cause this.
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Old 04-25-2014, 03:35 PM   #11
quazimoto
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Quote:
Originally Posted by car_freak85 View Post
I was finally able to swap back to new OEM hoses and, amazingly, the strange boosting is gone (reset the ECU as well).

I still don't get why the silicone hoses would cause this.
Because they probably were not the same ID as the OEM hoses. Not rocket science.
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