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Old 01-18-2020, 11:32 PM   #1
boostedninja
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Default Boost creep question

I have an 05 Subaru wrx I just bought not too long ago , I did some repairs last owner didnít really take good care of her , everything is stock only has an hks bov and cat back that I installed myself , I also gutted the up pipe , turbo has been rebuilt. I replaced the turbo inlet . The problem Iím having is that the car start to act weird when my boost gauge hits 15 lbs which Iím guessing itís boost creep , please help
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Old 01-19-2020, 12:35 AM   #2
subaru_gc8
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what does it do when its acting weird?
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Old 01-19-2020, 12:43 AM   #3
boostedninja
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Originally Posted by subaru_gc8 View Post
what does it do when its acting weird?


Feels like it looses power for a second
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Old 01-19-2020, 12:46 AM   #4
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Is it possible that the 3Ē cat back be causing this boost creep? I do have a stock down pipe tho
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Old 01-19-2020, 08:19 PM   #5
bugeyerex02
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Is it a boost leak? You sure everything is tight?
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Old 01-19-2020, 09:08 PM   #6
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You're guessing until you datalog the car. The factory ECU is a powerful tool when diagnosing these types of issues. Did your car come with a Cobb Accessport or Tactrix cable?

Was the car tuned after you gutted DP? If not, you're probably on borrowed time if you keep running it without at least tweaking wastegate duty cycle to compensate. I've seen the overboost that occurs first hand. If it knocks hard enough because of overboost, you'll feel a corresponding loss in power until the timing correction the ECU makes bleeds off.
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Old 01-20-2020, 06:56 AM   #7
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Originally Posted by awfulwaffle View Post
You're guessing until you datalog the car. The factory ECU is a powerful tool when diagnosing these types of issues. Did your car come with a Cobb Accessport or Tactrix cable?

Was the car tuned after you gutted DP? If not, you're probably on borrowed time if you keep running it without at least tweaking wastegate duty cycle to compensate. I've seen the overboost that occurs first hand. If it knocks hard enough because of overboost, you'll feel a corresponding loss in power until the timing correction the ECU makes bleeds off.

As far as I know the car has always been stock No EM , I donít have a tactrix cable but I can buy one I just have to freshen up in how to data log since it was 5 years ago when I had my last bug eye. I installed the stock BPV and stock exhaust but it still creeps , boost goes up to 15 psi fallowed by a flashing check engine light
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Old 01-20-2020, 07:09 AM   #8
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I'd get one for sure. You'll be able to record everything you need to diagnose, and post up logs here or on romraider forums if you need help.

Curious that it still overboosts with stock exhaust. When the turbo was replaced/rebuilt, were the factory rubber lines reinstalled that connect the wastegate actuator and compressor discharge port to the boost control solenoid? There's a restrictor ("boost pill") shoved into one of the lines, and if they were replaced without transferring that over your boost control won't work right. All of that is if you're still on the stock boost controller.
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Old 01-20-2020, 08:49 AM   #9
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He didn't guy the DP, he gutted the uppipe. Historically, no cat in the uppipe is a good thing, and rarely causes issues if it's not tuned for, other than pulling the EGT sensor from the bung causing a persistent CEL unless tuned out.

Untuned Aftermarket downpipes cause boost creep because the backpressure is reduced and the wastegate can't keep up with the speed at which boost builds on stock WDC'S. This is not the case here.

You say it throws a CEL after this behavior. What code is is throwing?
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Old 01-20-2020, 09:31 AM   #10
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[quote=awfulwaffle;46218791]I'd get one for sure. You'll be able to record everything you need to diagnose, and post up logs here or on romraider forums if you need help.

Curious that it still overboosts with stock exhaust. When the turbo was replaced/rebuilt, were the factory rubber lines reinstalled that connect the wastegate actuator and compressor discharge port to the boost control solenoid? There's a restrictor ("boost pill") shoved into one of the lines, and if they were replaced without transferring that over your boost control won't work right. All of that is if you're still on the stock boost controller.[/


Car didnít have a boost gauge when I bought it so I installed one and was only showing 5 lbs , I checked for restriction pill and it didnít have one so I got one from the Subaru dealer, after installation I was at 10 psi max , I checked for leaks and turbo inlet was leaking bad where it connects to turbo so I replaced it but as I had the turbo inlet off I removed the turbo and got it rebuilt as I waited I removed the up pipe and gutted it out since I read online that I can do it and not need to be tuned after. Then after all those things I started getting fuel cut off or boost creep
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Old 01-20-2020, 12:30 PM   #11
awfulwaffle
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Whoops read UP as DP. We do it in LGT land, agreed no tune needed.

So...was the boost pill reinstalled after the rebuild?

Have any yards with borked WRXs around? Could pull a boost control solenoid and swap for a quick check. If a solenoid from an 05 LGT works, I have several.

That said, I wouldn't keep running it till it cuts fuel until I logged the car and saw what was going on. But, I'm paranoid.
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Old 01-20-2020, 03:18 PM   #12
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Quote:
Originally Posted by awfulwaffle View Post
Whoops read UP as DP. We do it in LGT land, agreed no tune needed.

So...was the boost pill reinstalled after the rebuild?

Have any yards with borked WRXs around? Could pull a boost control solenoid and swap for a quick check. If a solenoid from an 05 LGT works, I have several.

That said, I wouldn't keep running it till it cuts fuel until I logged the car and saw what was going on. But, I'm paranoid.


Yeah Iím going to pull the BCS out and check if itís stuck
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Old 01-20-2020, 10:03 PM   #13
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So I checked the boost controller and it opens closes when 12 v applied , I scanned the car and got this P0303 code
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Old 01-21-2020, 01:58 AM   #14
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Quote:
Originally Posted by boostedninja View Post
Feels like it looses power for a second
Like there is a hesitation?
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Old 01-21-2020, 06:39 PM   #15
bugeyerex02
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That's a misfire. Your problem just became even more vague. Does it stop boosting at 15psi? Or is it misfiring at 15 and then cutting fuel?
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Old 01-24-2020, 05:09 PM   #16
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Update:
So after checking what the code was I went ahead and replaced #3 coil pack and went ahead and replaced all spark plugs with NGK iridium stock heat. The onceís i removed were Denso and they were gapped at 40 . The ngks I bought had a gap of 35 so I gapped them to 28 bc thatís what I read on a forum. After install I test drove and car runs fine , also when I removed the plugs they seem pretty loose felt like they were torque down to 5 lbs
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Old 01-24-2020, 05:45 PM   #17
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Btw thank you all who replied
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