# Mystery pipe



## Mikevally (Apr 12, 2010)

So I’m looking to install a big bore turbo inlet from a 1.4t mk6 jetta. The new turbo inlet has a barb for pcv but my question is about the stock turbo inlet on the 2021 golf 1.4t DGXA.
The stock inlet has two barbs coming off of it. One that leads to pcv and another that comes off the turbo inlet and goes to the charge pipe right before the throttle.
Does anyone know if this is safe to delete when I install my new charge pipe and inlet? The charge pipe doesn’t have the bung for this pipe anyway.
Is this some way of venting boost pressure instead of a blow off valve? Because I already run a blow off valve so depending on what this hose does maybe it can be deleted.


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## Mikevally (Apr 12, 2010)

I circled the two connectors in red and drew a diagram with yellow on where the pipe is. It seems to be some kind of pressure release pipe to compensate for not having a traditional diverter valve/bov set up.

can this hose be removed entirely with a bov installed? Like previously stated. The hose routes from the charge pipe to the turbo inlet.


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## Leirk (Oct 1, 2020)

What does the manufacturer of the big bore inlet say? Is it listed as fitting your vehicle? Good luck 🍀


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## Mikevally (Apr 12, 2010)

Big bore is technically for a Jetta 1.4tsi which only has the one port for pcv. The stock inlet has two barbs. One for pcv and this other mystery one.

All I’ve found is for Jetta stuff in regards to the turbo inlet, and those only have the one port for pcv. I’m thinking this is some type of pressure release, I’m gonna delete it and do some logs to see if anything changes. I have a blow off valve so if this is some pressure release I should be fine deleting it.


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## tsi20 (Sep 22, 2021)

Mikevally said:


> Big bore is technically for a Jetta 1.4tsi which only has the one port for pcv. The stock inlet has two barbs. One for pcv and this other mystery one.
> 
> All I’ve found is for Jetta stuff in regards to the turbo inlet, and those only have the one port for pcv. I’m thinking this is some type of pressure release, I’m gonna delete it and do some logs to see if anything changes. I have a blow off valve so if this is some pressure release I should be fine deleting it.


Have you verified that the inlet even is of the same type? I know the newer 1.4 is quite different from the older 1.4 from the MK6 Jetta.


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## Mikevally (Apr 12, 2010)

The inlet fits the turbo I know this. Bolts right up. Just only has one port instead of two. Stock has One port for pcv and a mystery port that leads right back to the charge pipe.


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## Mikevally (Apr 12, 2010)

I can’t seem to find the workshop manual for this model any where online or else I’d know what this part actually does.


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## tsi20 (Sep 22, 2021)

Mikevally said:


> I can’t seem to find the workshop manual for this model any where online or else I’d know what this part actually does.


Nothing that I know of besides erWin but it’s quite pricey.


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## Mikevally (Apr 12, 2010)

Found a diagram in the workshop manual that references at crankcase ventilation hose but that’s it. But based off its location I’m thinking it’s much less crank case breathing and more passive pressure reduction to reduce compress surge since these motors don’t naturally have blow off valves.


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## tsi20 (Sep 22, 2021)

Mikevally said:


> Found a diagram in the workshop manual that references at crankcase ventilation hose but that’s it. But based off its location I’m thinking it’s much less crank case breathing and more passive pressure reduction to reduce compress surge since these motors don’t naturally have blow off valves.


Just curious what is the reason behind why you want to change the inlet? Also what other mods do you currently have?


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## Mikevally (Apr 12, 2010)

I want to replace the factory plastic inlet with an aluminium inlet. I’m running, intake, turbo back exhaust, blow off valve, stage 1 tune. Plan on going 290rs turbo and front mount in the near future.


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