Diverter Valve or Blow off valve

[EricHarveyy]

I haven't seen much discussion around here on what people prefer or what they think benefits there car the most. I was looking at a new diverter valve because it seems to be the most logical and least obnoxious while driving. But are the benefits even that noticeable? Does anyone have any recommendations on what diverter valves or blow off valves to get and why?

[eljay]

I haven't seen much discussion around here on what people prefer or what they think benefits there car the most. I was looking at a new diverter valve because it seems to be the most logical and least obnoxious while driving. But are the benefits even that noticeable? Does anyone have any recommendations on what diverter valves or blow off valves to get and why?

http://forums.vwvortex.com/showthrea...ter-for-my-1-8
http://jettajunkie.com/vw-jetta/show...alve-on-a-1.8T
http://forums.vwvortex.com/showthrea...ve-vs-BOV-1-8t
http://www.audizine.com/forum/showth...Diverter-Valve

In summary: 1.8T is designed to run in recirculating mode. With BOV you are just dumping metered air out. I'm not knowledgeable enough to tell you what that is doing to your engine over time, but when metered air gets lost and the ECU still supplies fuel based on it, you will run rich.
There are valves like the Forge Splitter that are hybrid and let you adjust the amount of recirculation vs dump. I have one on my car. I haven't tried others to tell you whether it works better or worse. It does make a nice sound, but because of it everyone wants to race me at every intersection. So, I will be switching to an OEM 710P diverter valve soon.

[texasboy21]

Running a BOV dumps metered air (once measured from the MAF), which essentially creates a boost leak.

The ECU is looking and accounting for air that was in the system, and no longer is.

A DV is the way to go.

[diagnosticator]

Manual or Auto trans? With a tip auto trans, the DV has practically no effect on the throttle response, since the throttle does not snap closed during gear shifts.

[ModdedEuros]

Def go with a diverter valve. I would recommend GFB's DV. They all around make some really nice DVs which are popular for various applications. We have a GFB dv in every one of our cars here

https://www.moddedeuros.com/audi/a4/...iverter-valves

[OneSlowA4]

You can run a bov on later b6s (maybe all Im not 100% sure.) I believe since they have a wideband o2 and adjust afrs based on that. So technically it wouldn't be unmetered air anymore. However, there's no benefit to a bov other than a "pssssss" sound during shifts as the original setup is meant for a DV.

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[texasboy21]

You can run a bov on later b6s (maybe all Im not 100% sure.) I believe since they have a wideband o2 and adjust afrs based on that. So technically it wouldn't be unmetered air anymore. However, there's no benefit to a bov other than a "pssssss" sound during shifts as the original setup is meant for a DV.

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This is incorrect. Air enters through the MAF the is dump - boost leak. To run a BOV you'll need to be running a MAFless tune (for BAT applications).

[OneSlowA4]

This is incorrect. Air enters through the MAF the is dump - boost leak. To run a BOV you'll need to be running a MAFless tune (for BAT applications).

My b6 definitely has a wideband o2 and will adjust afrs regardless of what the maf says. You're correct that its unmetered but after driving the car it won't affect afrs as the ecu will adjust based on o2 readings which are all that matter lol. Look it up. I'm almost 100% positive.

B5s however have to run a mafless tune for a bov or afrs will be rich.

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[OneSlowA4]

Basically unless you're running a big turbo and high boost numbers your stock DV is fine. If you want to upgrade stay with a DV unless like I said you're running a high boost application. There's no need for a BOV. I'm not disagreeing with that texasboy21.

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[Seerlah]

The WB 02 sensor calculates your lambda (AFR) on your exhaust to make sure you have proper combustion. When the throttle body closes, that air being deflected back (blow back) by the throttle body flapper never made it's way into combustion chamber, let alone the exhaust for the 02 sensor to monitor it. With a BOV, that blow back that was already monitored by the ECU and MAF is now released into the atmosphere and the readings of your air intake is your system is now off. With that missing air, the ECU still thinks it's there. Till the primary 02 sensor senses you running rich (happens quick) due to already adding x amount of fuel because it was expecting y amount of air in the combustion chamber, your fueling won't be corrected.

With that being said, you can most def run a BOV on these cars as long as it's "closed at idle". Is it not suggested and frowned upon? Yep! Mostly because you want to do it for that ppppsssshhh sound all the cool kids are doing. And with that being said, I also run a bov but run a bigger turbo mafless application. But, would perform much better with a closed loop maf with dv system.

[jayiszraw]

Want noise? Get s splittr otherwise get a dv

[OneSlowA4]

The WB 02 sensor calculates your lambda (AFR) on your exhaust to make sure you have proper combustion. When the throttle body closes, that air being deflected back (blow back) by the throttle body flapper never made it's way into combustion chamber, let alone the exhaust for the 02 sensor to monitor it. With a BOV, that blow back that was already monitored by the ECU and MAF is now released into the atmosphere and the readings of your air intake is your system is now off. With that missing air, the ECU still thinks it's there. Till the primary 02 sensor senses you running rich (happens quick) due to already adding x amount of fuel because it was expecting y amount of air in the combustion chamber, your fueling won't be corrected.

With that being said, you can most def run a BOV on these cars as long as it's "closed at idle". Is it not suggested and frowned upon? Yep! Mostly because you want to do it for that ppppsssshhh sound all the cool kids are doing. And with that being said, I also run a bov but run a bigger turbo mafless application. But, would perform much better with a closed loop maf with dv system.

Okay I was mistaken. It adjusts afterwards it doesn't fully correct it. Either way it can be done without harm but is pointless.

Is there even a point to change the dv without other mods anyways? There's no performance gains.

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[texasboy21]

Okay I was mistaken. It adjusts afterwards it doesn't fully correct it. Either way it can be done without harm but is pointless.

Is there even a point to change the dv without other mods anyways? There's no performance gains.

The harm is your fueling will be off, which affects performance.

A DV is not a power mod, its a wear item. The factory DV uses a rubber diaphragm that over time (or with increased boost pressure) tears, causing incorrect operation. The aftermarket DVs use a metal spring a piston that cannot tear, are serviceable/rebuildable, and offer the availability to change to a softer or stiffer spring. WIthout any other mods on the car (mainly a tune) there is no need to go with anything other than OEM.

[OneSlowA4]

The harm is your fueling will be off, which affects performance.

A DV is not a power mod, its a wear item. The factory DV uses a rubber diaphragm that over time (or with increased boost pressure) tears, causing incorrect operation. The aftermarket DVs use a metal spring a piston that cannot tear, are serviceable/rebuildable, and offer the availability to change to a softer or stiffer spring. WIthout any other mods on the car (mainly a tune) there is no need to go with anything other than OEM.

\thread lol

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[Audi body]

This is incorrect. Air enters through the MAF the is dump - boost leak. To run a BOV you'll need to be running a MAFless tune (for BAT applications).

Mafless tune or a blow through maf. Which is what I'm running. Does measure the air till after the fmic.