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Replacing the VW / Audi Turbo Diverter Valve
 
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Pelican Technical Article:

Replacing the VW / Audi Turbo Diverter Valve

Peter Bodensteiner

Time:

1 hr

Tab:

$100

Talent:

****

Tools:

Screwdriver

Applicable Models:

Audi A4 (1997, 1999-01)
Audi A4 Sedan (1998)
Audi A4 Quattro (1997, 1999-01)
Audi A4 Quattro Sedan (1998)
Audi TT (2000-04)
Audi TT Quattro (2000-04)
VW Beetle (1999-02)
VW Golf (2000-02)
VW Jetta (2000, 2002)
VW Jetta Sedan (2001)
VW Passat (1998-00)

Parts Required:

Screw-type hose clamps to replace crimp-style clamps

Hot Tip:

Choose your diverter valve based on your power needs

Performance Gain:

A good diverter valve holds boost, lessens turbo lag, and prevents damage to the turbocharger

Complementary Modification:

Replace turbo, install boost controller

You may have heard this component called a pop-off valve, a compressor bypass valve, a turbo cut-off valve, and a number of other things; in Audi parlance, it is called a Diverter Valve (DV).

In all cases, this part performs the same general functions. The DV is connected to the engine's intake tract by two hoses, one just before the turbocharger's compressor wheel and one just after. It also receives a vacuum signal from a line that connects to the intake manifold, after the throttle body.

The need for the DV stems from the fact that the turbocharger, driven by exhaust gases, keeps building boost even after the engine's throttle is closed. However, with the throttle plate closed, the pressurized air has nowhere to go. The boost builds up in the intake tract between the turbo and the throttle plate; without an outlet, the pressure can bounce back into the turbo's compressor wheel and stall it, and potentially damage the turbo.

The DV vents air out of this portion of the intake tract. You have no doubt noticed a "Pssh" sound coming out from under the hood of a turbocharged car at some point--this is the sound of the valve doing its work. It's not unusual for people who have modified their cars to set up their valve to vent the air to atmosphere to make this distinctive sound louder, but this is a bad idea for two reasons. First, in most cars this air has already been "counted" by the engine's computer, so it will inject more fuel to account for this air, and when the air does not appear, the engine will receive too much fuel. Secondly, if the valve is allowed to recirculate the air back into the intake tract ahead of the turbo, as it is designed to do, it helps keep the compressor wheel spinning. By keeping the wheel spinning, when you crack the throttle again the wheel has less catching up to do, and turbo lag (the delay between throttle application and the arrival of boost to the engine) is reduced.

The DV that comes stock in the B5 A4 works just fine for a stock setup, although it is made of plastic and can fail over time. An indication of this is if your engine won't hold boost like it used to. Without a boost gauge to monitor your engine it's hard to quantify this, but the loss of power should be noticeable.

If you increase the boost level to your engine, either through a new turbocharger or revised tuning, you will need to upgrade your DV. Audi itself knows this, as they supply 225 hp applications of the 1.8T with an upgraded DV called the 710N (the stock 150 hp model is simply 710). Put simply, the additional boost in the intake tract can force the lesser DV open, preventing your engine from seeing the boost (and producing the additional horsepower) that it should.

The DV is located toward the front of the engine compartment, directly ahead of, and a few inches below, the turbocharger. You can replace it without moving the radiator support panel into the service position, although this will certainly make access easier; The photographs below show the panel in the service position. Alternatively, you could do much of the work from below the car, provided you've removed the plastic belly panel. From below, your main obstacle will be the large intake hose running from the turbo to the hard pipe that takes air across the front of the car to the driver's side-mounted intercooler.

As noted, the valve has three connections--two larger hoses and one small one. Installation of your new DV is essentially a matter of disconnecting these hoses from the old DV and installing them on the new one. The DV has no mounting bracket as it is a lightweight component. In effect, the short hose between the DV and the lower intercooler hose serves as its support.

It's hard to actually see the DV in this photo, despite the fact that the radiator support panel is in the forward position and thus there's more room to see it.
Figure 1

It's hard to actually see the DV in this photo, despite the fact that the radiator support panel is in the forward position and thus there's more room to see it. It's right behind that corrugated hose (green arrow). The vacuum signal that actuated the valve is delivered by the thin hose with the braided fabric exterior (purple arrow). The hose running off to the right from the DV delivers air into the intake tract just before the turbo's compressor wheel (blue arrow). Just below the DV, you can see the screw head on the clamp that helps hold the hose in place between the DV and the intake tract after the turbocharger (yellow arrow).

Use a flat-blade screwdriver or a nut driver to loosen the aforementioned clamp.
Figure 2

Use a flat-blade screwdriver or a nut driver to loosen the aforementioned clamp.

With the DV moved slightly out of the way, you can see the short hose that runs between the DV and the intake tract after the turbo (green arrow).
Figure 3

With the DV moved slightly out of the way, you can see the short hose that runs between the DV and the intake tract after the turbo (green arrow).

Loosen the crimp-style clamp that secures the hose that runs between the DV and the intake just before the turbo.
Figure 4

Loosen the crimp-style clamp that secures the hose that runs between the DV and the intake just before the turbo. You'll want to replace this clamp with a screw-type clamp.

Last, remove the vacuum hose from this nipple in the center of the DV.
Figure 5

Last, remove the vacuum hose from this nipple in the center of the DV. You can insert a small screwdriver into the clamp to loosen it.

Here's the new metal DV compared to the old plastic one on the right.
Figure 6

Here's the new metal DV compared to the old plastic one on the right.

This angle comparing the two valves shows the difference in size between the two, particularly in the valve that directs air back to the intake tract ahead of the turbo.
Figure 7

This angle comparing the two valves shows the difference in size between the two, particularly in the valve that directs air back to the intake tract ahead of the turbo. Also note the oil residue that has built up in the old valve. This oil comes via the engine's crankcase ventilation system.

This aftermarket DV came with this swivel attachment for the vacuum hose nipple, which allows for more flexibility in installing the DV.
Figure 8

This aftermarket DV came with this swivel attachment for the vacuum hose nipple, which allows for more flexibility in installing the DV. It is optional--you could simply use the nipple right on the valve if you wish.

Here the DV has been reattached to the vacuum hose, as well as the hose leading to the intake tract pre-turbo.
Figure 9

Here the DV has been reattached to the vacuum hose, as well as the hose leading to the intake tract pre-turbo. As mentioned earlier, I used a zip tie to secure the hose; a screw clamp would have been a better solution for replacing the crimp-style clamp.

All that is left is to insert the DV into the short hose leading to the post-turbo intake tract.
Figure 10

All that is left is to insert the DV into the short hose leading to the post-turbo intake tract.

The DV is installed.
Figure 11

The DV is installed. This photo shows the full length of the hose leading to the intake tract, just as the intake attaches to the compressor intake of the turbocharger (the snail-shaped component in the upper right in this photo. The darker hose behind it carries the air out of the compressor side of the turbo. It's a little convoluted, but you can see the entire recirculation loop that is served by the DV in this photo.

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Comments and Suggestions:
vinicius silveira Comments: hello,

im from Brazil and i need central panel complete of my volvo xc60 t% dynamic year 2011.

Do you have ? How much ?

Thanks
June 7, 2016
  Followup from the Pelican Staff: I’m not the best with part numbers.

To be sure, Give our parts specialists a call at 1-310-626-8765 - Nick at Pelican Parts
 
SeaDawg Comments: MAF mass airflow sensor. If it does not exist i.e., some other mechanism is used to measure air-fuel ratios, like the O2 sensors in the exhaust line I assume that using a BOV blow off valve, to atmosphere instead of a DV diverter/compressor bypass valve would mean you would NOT suffer from the 'first' problem you stated in your write-up 'counted' air for fuel-air mixture.

If this is true, using a BOV to atmosphere would only cause new/added turbo lag since the DV would no longer be present to recirculate air for helping the compressor wheel to spin. So I'm thinking it wouldn't lead to reduction in final boost, rather it would only increase the lag time for the compressor to spool back up.

Thanks!
February 15, 2016
  Followup from the Pelican Staff: What are you trying to fix? Engines using calculated mass air flow can still have air volume faults and fuel trim faults. The DME expects x-amount of air volume whether measured through speed density method or air mass method. - Nick at Pelican Parts  
SeaDawg Comments: Oops, I meant to add which vehicle has me pondering such thoughts:

2016 VW Golf R MK7 USA; 2.0 TSI; Gasoline; M/T; Stock.
February 13, 2016
  Followup from the Pelican Staff: Got the vehicle info, thanks. - Nick at Pelican Parts  
SeaDawg Comments: After days of research and many forum trolls, I finally found a write-up that makes sense, thank you!

If the vehicle doesn't have a MAF, using a BOV i.e., vent to atmosphere instead of a DV shouldn't suffer from the air-fuel-richness problem, right? In theory, I'd assume using a BOV instead of a DV would only lead increasing turbo lag. Agree?
February 13, 2016
  Followup from the Pelican Staff: Can you spell out the initialisms? This way I can be sure what you are referring to. - Nick at Pelican Parts  
audimoneypit Comments: Is there a wrong direction to install this? I got turned around after I removed it and don't know which hose goes to which specific port. The pictures aren't helping and I don't want to screw up this car anymore.
December 9, 2015
  Followup from the Pelican Staff: Yes, there is. The pressure relief vent should face away from the boost hose toward the intake. - Nick at Pelican Parts  
Pras Comments: I'm also loosing power on my Passat 1.8t let me check this dv.
May 16, 2015
  Followup from the Pelican Staff: Let us know what you find. - Nick at Pelican Parts  
smokey jetta Comments: hi, is there a way to eliminate the turbo totally on a vw.1.8? turbo is blown.would like to by-pass it completely.thanks.
April 22, 2015
  Followup from the Pelican Staff: Not that I am aware of. - Nick at Pelican Parts  
John Comments: Follow up to my previous comment, my diverter valve seems to cause my turbo to make the flutter sound. Once the car warms up about 10 to 20 minutes after driving it gives the regular whoosh sound. Is there any particular reason this is happening I thought it might be because the DV is dirty.
January 3, 2015
  Followup from the Pelican Staff: The diverter could be receiving a faulty vacuum source from the solenoid. I would test vacuum to the diverter when the problem is present. - Nick at Pelican Parts  
John Comments: I have a DV that looks exactly like the aftermarket one, I bought the car used with no idea what the make and model is. How often should I clean this part, and is there any special method?

Thanks~
January 3, 2015
  Followup from the Pelican Staff: Shouldn't have to clean it. - Nick at Pelican Parts  
Creekflea Comments: Hey Bick,
If my stock valve is bad will I see any fault codes
December 12, 2014
  Followup from the Pelican Staff: Yes, you could have boost pressure fault codes. - Nick at Pelican Parts  
spencer22 Comments: Hey I was wondering if it is possible to install both a diverter valve and a manual boost controller?
November 19, 2014
  Followup from the Pelican Staff: You didn't mention what vehicle you have. But this is possible on most turbocharged engines. - Nick at Pelican Parts  
saneesh8 Comments: Thanks Nick. Any advantage in putting the 225HP one now? I mean with no chipping?
October 8, 2013
  Followup from the Pelican Staff: Opinions vary on this subject. I would think it would be OK to install it without DME software. If you are on the fence, contact the folks at Mode, they will be glad to answer your questions. Here is a linkt o the product brochure:
http://www.modeincparts.com/index_files/MODE_Boost_Valves_NP.pdf - Nick at Pelican Parts
 
saneesh8 Comments: How do i know that the DV on my car is 225 HP or the old one? It is completely stock car and is 2002 Passat AWM with 1.8T. I heard that my car may or may not have the 225 HP one.
October 4, 2013
  Followup from the Pelican Staff: If it is black plastic and stock, it is likely not the 225hp model. - Nick at Pelican Parts  

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