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Cobb Tuning Boost Leak?

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cinciGTI25

New member
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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BudgetPhoenix

Autocross Champion
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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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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cinciGTI25 said:
Thanks! No trouble codes reported by the AP. The DV I have is this one:

https://www.ecstuning.com/b-forge-parts/20t-diverter-valve/fmdvfsitv/ and I'm wondering if there could be an issue associated with it?
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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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cinciGTI25

New member
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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cinciGTI25

New member
notovicrious said:
Stage 1+ dials you in at around 15-16psi peak.
Click to expand...

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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cinciGTI25 said:
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?
Click to expand...



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.
 
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cinciGTI25

New member
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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cinciGTI25 said:
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.
Click to expand...



The car never felt this way before? How new are you to the tune/car? You will experience a slight jar inbetween gears when WOT and DSG. 16psi isn’t much but maybe you’re just not used to the power bro?
 
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