Surging Noise After Forge DV Install

ArweenX1 · 11-01-2017, 11:58 PM

What's up guys.
Currently on the car are oem location vrsf inlets and BMS dci. Recently installed Cobb charge pipe and forge dv. At low throttle there's a loud surging noise for a couple seconds and then it goes away. Can't figure out what's causing it.

I have a sound clip. If anyone wants me to send to them.

Any info is much appreciated!

Chris@VargasTurboTech · 11-02-2017, 12:34 PM

Make sure to use a dedicated line to the forge, they don't mandate it in their literature (best I know) but they benefit from an upgraded line.

Also make sure you use the correct spring. Forge tends to recommend springs based on boost pressure, not vacuum, which IMO is the wrong way to do it. When in doubt use a softer spring. If it doesn't hold boost something else is wrong.

Chris

ArweenX1 · 11-02-2017, 12:37 PM

Quote:

Originally Posted by Chris@VargasTurboTech

Make sure to use a dedicated line to the forge, they don't mandate it in their literature (best I know) but they benefit from an upgraded line.

Also make sure you use the correct spring. Forge tends to recommend springs based on boost pressure, not vacuum, which IMO is the wrong way to do it. When in doubt use a softer spring. If it doesn't hold boost something else is wrong.

Chris

Are u referring to drilling the hole in the intake manifold? Cause I would really like to avoid that lol and also it's the stock spring it came with. I believe the green ones.

Chris@VargasTurboTech · 11-02-2017, 12:38 PM

Yep, drilling a hole in the mani and putting a nicer/bigger line to the BPV's. You have two of the BPV's, so it's even more important. It's not a big deal if you take your time and work slowly.

Chris

ArweenX1 · 11-02-2017, 12:43 PM

Quote:

Originally Posted by Chris@VargasTurboTech

Yep, drilling a hole in the mani and putting a nicer/bigger line to the BPV's. You have two of the BPV's, so it's even more important. It's not a big deal if you take your time and work slowly.

Chris

Will that fix the surging noise that's happening down low? Don't have this car for to much longer and would like to avoid permanent mods if possible.

Chris@VargasTurboTech · 11-02-2017, 12:54 PM

Quote:

Originally Posted by ArweenX1

Will that fix the surging noise that's happening down low? Don't have this car for to much longer and would like to avoid permanent mods if possible.

Hold the keyboard closer to your car so I can tell....

Try a softer spring in the forge first... see if that helps you out. It's not ideal but might get you close enough.

Chris

Ilma · 11-02-2017, 04:54 PM

Lol.....before doing anything else, check if there are YELLOW springs in the package. If so - swap to the yellow ones.

The green ones don't hold enough boost and are too soft, so they are probably venting too soon, which is probably making the noise you are hearing.

ArweenX1 · 11-02-2017, 05:17 PM

Quote:

Originally Posted by Ilma

Lol.....before doing anything else, check if there are YELLOW springs in the package. If so - swap to the yellow ones.

The green ones don't hold enough boost and are too soft, so they are probably venting too soon, which is probably making the noise you are hearing.

Didn't come with any additional springs. Just to be sure, this is what I'm looking for correct?
https://www.forgemotorsport.com/Upra...duct--825.html

mfractal · 11-02-2017, 05:28 PM

Quote:

Originally Posted by ArweenX1

Quote:

Originally Posted by Ilma

Lol.....before doing anything else, check if there are YELLOW springs in the package. If so - swap to the yellow ones.

The green ones don't hold enough boost and are too soft, so they are probably venting too soon, which is probably making the noise you are hearing.

Didn't come with any additional springs. Just to be sure, this is what I'm looking for correct?
https://www.forgemotorsport.com/Upra...duct--825.html

I am positive that the forge kit comes with an extra yellow spring. Weird yours came without it but I doubt it's your problem. I haven't had any such noises on the green OR yellow springs.

ArweenX1 · 11-02-2017, 05:43 PM

Quote:

Originally Posted by mfractal

Quote:

Originally Posted by ArweenX1

Quote:

Originally Posted by Ilma

Lol.....before doing anything else, check if there are YELLOW springs in the package. If so - swap to the yellow ones.

The green ones don't hold enough boost and are too soft, so they are probably venting too soon, which is probably making the noise you are hearing.

Didn't come with any additional springs. Just to be sure, this is what I'm looking for correct?
https://www.forgemotorsport.com/Upra...duct--825.html

I am positive that the forge kit comes with an extra yellow spring. Weird yours came without it but I doubt it's your problem. I haven't had any such noises on the green OR yellow springs.

Yea it seems off, I'll contact them Tommorow and see if it's supposed to be included. Also I have inlets that's why I'm assuming its making the surge noise with the weaker spring under low Rpms. Quick question is this the proper spring for them? https://www.forgemotorsport.com/Upra...duct--825.html

Ilma · 11-02-2017, 06:40 PM

Quote:

Originally Posted by ArweenX1

Didn't come with any additional springs. Just to be sure, this is what I'm looking for correct?
https://www.forgemotorsport.com/Upra...duct--825.html

Yup.........it states right in their ad that the green springs are only rated for 5-10 psi.

bradsm87 · 11-10-2017, 04:19 AM

Quote:

Originally Posted by Ilma

Yup.........it states right in their ad that the green springs are only rated for 5-10 psi.

It also says:

"Note: The quoted spring pressure (PSI) relates to the un-assisted clamping force of the spring and should NOT be taken as an equivalent to boost pressure when determining suitability. Once a valve is fitted to a car it is subjected to various pressures that act upon the diaphragm or piston to aid its respective ability to seal or hold boost. An example of this, would be when using a FMCL007P valve on a 1.8T engine as found in the TT 225hp. The boost pressure on a "chipped" car can peak at 26psi. The recommended spring would be the Green or Yellow."

A spring can't be rated to a positive boost pressure, only a vacuum pressure before venting. I'd personally use the green spring. The stock DVs start to open at only -3.5psi vacuum.

Chris@VargasTurboTech · 11-11-2017, 10:58 AM

Quote:

Originally Posted by bradsm87

It also says:

"Note: The quoted spring pressure (PSI) relates to the un-assisted clamping force of the spring and should NOT be taken as an equivalent to boost pressure when determining suitability. Once a valve is fitted to a car it is subjected to various pressures that act upon the diaphragm or piston to aid its respective ability to seal or hold boost. An example of this, would be when using a FMCL007P valve on a 1.8T engine as found in the TT 225hp. The boost pressure on a "chipped" car can peak at 26psi. The recommended spring would be the Green or Yellow."

A spring can't be rated to a positive boost pressure, only a vacuum pressure before venting. I'd personally use the green spring. The stock DVs start to open at only -3.5psi vacuum.

Ding ding ding! Well said.

They all work about the same way. We subscribe to the way Tial recommends it be set up, which is more based on vacuum than boost.

Chris

mfractal · 11-14-2017, 06:28 AM

so basically if the car sees around 10psi of vaccum we should set the spring accordingly

11-01-2017, 11:58 PM	#1
ArweenX1 Private First Class 19 Rep 108 Posts Drives: 2009 E90 LCI 335i Join Date: Mar 2016 Location: Buffalo, NY iTrader: (0)	Surging Noise After Forge DV Install What's up guys. Currently on the car are oem location vrsf inlets and BMS dci. Recently installed Cobb charge pipe and forge dv. At low throttle there's a loud surging noise for a couple seconds and then it goes away. Can't figure out what's causing it. I have a sound clip. If anyone wants me to send to them. Any info is much appreciated!
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11-02-2017, 12:34 PM	#2
Chris@VargasTurboTech Lieutenant Colonel 1933 Rep 1,532 Posts Drives: All Things TurboCharged Join Date: May 2016 Location: Bay Area iTrader: (0)	Make sure to use a dedicated line to the forge, they don't mandate it in their literature (best I know) but they benefit from an upgraded line. Also make sure you use the correct spring. Forge tends to recommend springs based on boost pressure, not vacuum, which IMO is the wrong way to do it. When in doubt use a softer spring. If it doesn't hold boost something else is wrong. Chris
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11-02-2017, 12:38 PM	#4
Chris@VargasTurboTech Lieutenant Colonel 1933 Rep 1,532 Posts Drives: All Things TurboCharged Join Date: May 2016 Location: Bay Area iTrader: (0)	Yep, drilling a hole in the mani and putting a nicer/bigger line to the BPV's. You have two of the BPV's, so it's even more important. It's not a big deal if you take your time and work slowly. Chris
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11-02-2017, 04:54 PM	#7
Ilma Colonel 184 Rep 2,841 Posts Drives: 2008 135i Join Date: Nov 2008 Location: Mississauga iTrader: (0)	Lol.....before doing anything else, check if there are YELLOW springs in the package. If so - swap to the yellow ones. The green ones don't hold enough boost and are too soft, so they are probably venting too soon, which is probably making the noise you are hearing.
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11-14-2017, 06:28 AM	#14
mfractal VAG Survivor $mfractal's Avatar$ 40 Rep 150 Posts Drives: E90 335i Join Date: Aug 2015 Location: BR iTrader: (1)	so basically if the car sees around 10psi of vaccum we should set the spring accordingly __________________ F10 535i LCI, Hybrid Turbo, Custom Inlet, Spool FX-150 Pump HPFP, TI Automotive LPFP, DV+, Phoenix IC, FTP CP, High Flow Cat, M5 Mufflers, Custom Tuned By David Shoup.
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