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Old 08-30-2019, 03:30 PM   #1
Kenterson
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Member#: 503172
Join Date: Jun 2019
Question Wastegate Boost Troubleshooting

Hey all,

I have a pro-tuned EJ207 V7 running the stock VF30 and am having issues getting the car to run past wastegate spring boost levels (~8-9 psi).

When doing a pull, the engine runs normally up to this boost level. At this level of boost, a few things happen:

1. The car jerks and I get some afterfire, which I assume means I'm running lean.

2. The exhaust note changes noticeably; it gets deeper and more 'rough' sounding.

3. If I leave the throttle down, the boost oscillates around this amount and the RPM will remain basically constant or increase very slowly.

Offhand, this sounds to me like a pre-turbo exhaust leak only present in boost, but I'll have to do some testing to determine if it's a boost control issue or mechanical issue first. I will also be getting underneath the engine tomorrow to look for carbon deposits on the exhaust manifold or up-pipe.

I'll be data-logging a few pulls both before and after unhooking the wastegate actuator vacuum line and posting those here once I finish getting RomRaider set up again. I, unfortunately, don't have a wideband to track my own AFR's yet.

My first thought was to check the BCS vacuum lines to ensure it was pulling reasonable vacuum from the intake side, but they all seem to be hooked in securely and in good condition.

Any other ideas to help me track this down? As a last resort, I have IAG nearby who can go through it for me as well, they can just be pretty backlogged on shop time.


JDM EJ207 V7 (w/ USDM 02 WRX ECU)
VF30
Cobb SRI w/ Mishi Turbo Inlet
Invidia Turboback w/ Catted DP
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Last edited by Kenterson; 08-30-2019 at 03:38 PM. Reason: Rich to lean on afterfire
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Old 08-30-2019, 11:48 PM   #2
Valarius Starchaser
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Join Date: Dec 2016
Chapter/Region: MWSOC
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Hybrid 6MT Swapped WRB

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Turbo inlet issue or boost leak or boost control solenoid lines

Start with a boost leak test and proceed from there

BCS lines get brittle though and are the easiest to service no matter what just be sure to put the restrictor pill back in the T by the wastegate
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Old 08-31-2019, 01:03 AM   #3
subaru_gc8
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unhook the wastegate and go driving, if you can get past the 8 or 9 lbs then you know its your bcs
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Old 09-03-2019, 02:36 PM   #4
Wizmalifa
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Quote:
Originally Posted by subaru_gc8 View Post
unhook the wastegate and go driving, if you can get past the 8 or 9 lbs then you know its your bcs


Does this 100% prove there is a BCS issue? My BCS will click with power applied directly to it but won’t boost of 7-8 psi. Then unhook the vacuum line and I can get to stock boost pressure easy.
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Old 09-07-2019, 01:24 PM   #5
subaru_gc8
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Quote:
Originally Posted by Wizmalifa View Post
Does this 100% prove there is a BCS issue? My BCS will click with power applied directly to it but won’t boost of 7-8 psi. Then unhook the vacuum line and I can get to stock boost pressure easy.
there are other questions like did the car ever run correctly? I would try to swap a bcs and see if that helps inorder for you not get boost if you have a exhaust leak, it would ahve to be a pretty big leak, and you can normally see them as there will be a black soot where the leak would be so it should be easy to see
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