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Old 11-05-2017, 10:55 PM   #1
cinciGTI25
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Cobb Tuning Boost Leak?

Trying to figure out if I have a boost leak. I have a 2013 Golf GTI DSG with a Cobb intake, Stage 1+ tune, Forge DV. I used to get 16psi consistently with the tune and just this past week, I've notice some hesitation when I'm in automatic and it feels like the car is "muddy." I plugged in the Cobb tuner and noticed I'm only getting 10psi of boost at most.

Sorry for the noob question, but is this a boost leak and how can I track down what the issue is?


Thanks in advance.


Brian
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Old 11-05-2017, 10:59 PM   #2
BudgetPhoenix
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Make a boost leak tester for use with an air compressor or do a 3rd or 4th gear pull and log requested and actual boost.
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Old 11-05-2017, 11:00 PM   #3
notovicrious
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Using the AP check for trouble codes. If none then check hose clamps and intake piping to and from the turbo. Make sure you have the newest revision DV (C) and ditch the forge spacer. Grab a GFB DV+
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Old 11-05-2017, 11:13 PM   #4
cinciGTI25
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Quote:
Originally Posted by notovicrious View Post
Using the AP check for trouble codes. If none then check hose clamps and intake piping to and from the turbo. Make sure you have the newest revision DV (C) and ditch the forge spacer. Grab a GFB DV+
Thanks! No trouble codes reported by the AP. The DV I have is this one:

https://www.ecstuning.com/b-forge-pa...lve/fmdvfsitv/ and I'm wondering if there could be an issue associated with it?
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Old 11-05-2017, 11:18 PM   #5
cinciGTI25
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Also - could it be a vacuum leak?
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Old 11-06-2017, 07:00 AM   #6
notovicrious
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Cobb Tuning Boost Leak?

Quote:
Originally Posted by cinciGTI25 View Post
Thanks! No trouble codes reported by the AP. The DV I have is this one:

https://www.ecstuning.com/b-forge-pa...lve/fmdvfsitv/ and I'm wondering if there could be an issue associated with it?


Ok well, this DV is fine and shouldn’t be the problem unless the hoses are torn or loose somewhere. You have to trace the intake hoses and clamps all the way to the turbo, then check turbo outlet pipe to the intercooler and then the charge pipe to the engine (throttle). Do you have any upgraded turbo piping after the turbo? Main thing is check for boost leaks within that whole system. If you’ve never touched them I wold focus on the DV set up and make sure everything is tight. Also how many miles are you at and have you or someone been doing the necessary services accordingly?
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Old 11-06-2017, 09:04 AM   #7
cinciGTI25
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notovicious - I checked all the hoses and they look solid. I'm going to take a look into the DV valve by taking it to the shop where I had it installed and is tight. Given I have no CEL, i'm going to guess it's a vacuum leak associated with the DV. The connection off the PCV looks oily, I'm wondering if the PCV valve is going bad and I need to replace it?
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Old 11-06-2017, 09:44 AM   #8
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What does the tune call for is psi? Have you added any parts since you were getting the 16?
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Old 11-06-2017, 09:58 AM   #9
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What does the tune call for is psi? Have you added any parts since you were getting the 16?


Stage 1+ dials you in at around 15-16psi peak.
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Old 11-06-2017, 02:04 PM   #10
cinciGTI25
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Originally Posted by notovicrious View Post
Stage 1+ dials you in at around 15-16psi peak.
Quick update - realized I was on v103 and re flashed to v104. I regained the 15 - 16psi, but now am getting a hard shift when in DSG. I'm currently wondering if this issue may be transmission / vacuum line related.

Thoughts?
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Old 11-06-2017, 02:07 PM   #11
notovicrious
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Cobb Tuning Boost Leak?

Quote:
Originally Posted by cinciGTI25 View Post
Quick update - realized I was on v103 and re flashed to v104. I regained the 15 - 16psi, but now am getting a hard shift when in DSG. I'm currently wondering if this issue may be transmission / vacuum line related.

Thoughts?


Tranny wouldn’t affect boost. What gas are you running in it and is the tune catering this gas? Example: Stage 1+ v104 93 with 91 or lower in the tank is no bueno. Besides v104 is the same as 103 with added features like burnout, 2step and launch control or for manual guys, flat foot shifting.

Last edited by notovicrious; 11-06-2017 at 02:13 PM.
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Old 11-06-2017, 02:28 PM   #12
cinciGTI25
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Running Shell 93, always.
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Old 11-06-2017, 03:30 PM   #13
notovicrious
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Originally Posted by cinciGTI25 View Post
Running Shell 93, always.


So you don’t have a boost leak and you regained proper boost levels with a flash to v104? Explain the hard shifts.
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Old 11-06-2017, 05:03 PM   #14
cinciGTI25
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You probably think I'm being crazy... I'm actually a pretty savvy car guy.

Hard shifts are coming when I'm in DSG mode, not full automatic. When I get up to full boost (15-16 psi) and hit the paddle to shift, it's a very HARD shift, not enough to make the car shake, think more of the clutch engaging hard when shifting. Back when I had a manual, I would liken it to dropping the clutch hard during a shift.

Still not sure that it's not a vacuum leak going to the DV valve that was causing the boost loss, but also wondering about the hard shifts now. Not sure if they are related or concurrent issues.
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