n249 bypass

[olliep]

is there an actual guide for this anywhere?

 

[adam cupra 20vt]

Ok guys, VAG-COM logs reveal no increase or decrease in performance and no fault codes with the N249 bypassed. Dump reaction is much quicker and throttle response seems improved.

I make no apologies for the "dirtiness" of my engine bay. Its there to propel the car, not to look all pretty.

On the AUQ engined Leon 1.8T Cupra and Sport, it should look something like this:

Here's a labelled diagram that is pretty self explanatory:

1. Remove the vacuum hose between the Fuel Pressure Regulator (FPR) and the underside of the intake manifold.

2. Use 4mm silicone vacuum hose and go direct from newly freed Vac port on intake manifold to top of DV.

3. Put a 6mm BRASS T-piece in the new hose parallel to the FPR and run another length of hose to the FPR vacuum port.

4. Cable Tie the new vac hose wherever it connects to something else.

5. Remove the Vacuum resevoir (Ugly black plastic thing directly over the No.4 cylinder coil pack). The hose going into it simply pulls off.

6. Plug the Vac Resevoir hose with a bolt and clamp it in there with a worm drive or jubilee clip. Do the same with the hose that used to be connected to the top of the Dump valve.


I recommend using brass t-pieces as they don't go brittle and snap when exposed to heat and oil, plastic does. Use cable ties rather than jubilee clips on the silicone hose you've fitted.

I hope this is a help to Leon Cupra owners who haven't seen the need to fit an LCR intake manifold.

Hi mate just wondering if you had had any problems since doing this? no fault codes or anything bad so far?

I know it says no fault codes I just want to be sure now its been done a while

Is it worth doing in your opinion?

 

[Cupra Ross]

Adam,

Still no fault codes apart from a lazy Forge DV which will be getting a good clean and service tomorrow. My personal car doesn't like cold starts with the N249 bypassed, I have no idea why. More often than not, it'll limit boost above 3000rpm on the first start of the day. Turning the engine off and re-starting puts everything back to normal and it doesn't re-occur for the rest of the day.

I'd say that unless you have a fault with the N249 cutting boost or are desparate to have an "object free" cam cover, its probably best just to leave everything as VW intended. The sharper dump sound is nice though.

 

[adam cupra 20vt]

I have no problems and my forge valve has only been on about 6hrs so don't think it needs a service. lol

I did just buy 2m of 4mm hose and a 6mm brass T piece off ebay....but seeing as I don't have any problems with boosting and I dont have my re-map yet I'll prob keep it until I do.

Cheers for the reply much appriciated

 

[Cupra Ross]

No problem mate. For all the time it takes, its probably worth having a go. Your car might run fine like this.

 

[adam cupra 20vt]

Yeah I will prob give it a go mate.....I can always put it back again.

 

[jordyboy004]

waiting for my dv to arrive on wednesday, is it worth doing this with the standard one on. just sort of preping it ready for when my forge arrives or shall i just wait and do it wednesday.

 

[CupraUK]

Thanks Cupra Ross for the LC guide. Did mine today, much faster DV respsonse.

Another avantage of this mod is that you can replace the 4th coil pack at the side of the road without tools. I carry a spare so it would save an RAC call out.

Here's a pic, I went for the stealth option of black hose.

 

[Cupra Ross]

Good work, well done mate.

 

[greesha]

Ok guys, VAG-COM logs reveal no increase or decrease in performance and no fault codes with the N249 bypassed. Dump reaction is much quicker and throttle response seems improved.

I make no apologies for the "dirtiness" of my engine bay. Its there to propel the car, not to look all pretty.

On the AUQ engined Leon 1.8T Cupra and Sport, it should look something like this:

Here's a labelled diagram that is pretty self explanatory:

1. Remove the vacuum hose between the Fuel Pressure Regulator (FPR) and the underside of the intake manifold.

2. Use 4mm silicone vacuum hose and go direct from newly freed Vac port on intake manifold to top of DV.

3. Put a 6mm BRASS T-piece in the new hose parallel to the FPR and run another length of hose to the FPR vacuum port.

4. Cable Tie the new vac hose wherever it connects to something else.

5. Remove the Vacuum resevoir (Ugly black plastic thing directly over the No.4 cylinder coil pack). The hose going into it simply pulls off.

6. Plug the Vac Resevoir hose with a bolt and clamp it in there with a worm drive or jubilee clip. Do the same with the hose that used to be connected to the top of the Dump valve.


I recommend using brass t-pieces as they don't go brittle and snap when exposed to heat and oil, plastic does. Use cable ties rather than jubilee clips on the silicone hose you've fitted.

I hope this is a help to Leon Cupra owners who haven't seen the need to fit an LCR intake manifold.

Im just in the process of doing n249 bypass

CupraRoss how did unplug hose that is connected to vac reservoir ? Force it out ? cut it ?

 

[CupraUK]

it just pulls out, bit of brute force required!

 

[Cupra Ross]

it just pulls out, bit of brute force required!

It shouldn't be difficult to remove once you get that stupid one time use clamp off. Put a flat bladed screwdriver tip at the top of the hose and prise it off, it'll be stuck there due to the temperature and the rubber starting to bond.

 

[greesha]

All done and works. I have 2 T-pieces in a row cause i also installed boost gauge but all seems ok. Time to check vag com. DV sound is much nicer now. I have cleaned throttle body as well today



EDIT. and i need to install that dog bone mount as well now ;p

 

[adam cupra 20vt]

I didn't get round to doing mine today as it took me 4 hours to fit my TIP pipe I might do it tomorrow tho but I'm just wondering if its best to remove the box over the 4th coilpack or leave it on? I think I red on the golf forum its best to leave it inplace as unplugging it can cause problems?

Whats best you reckon?

 

[Phillc]

Now all you need to do is get rid off the evap, secondary air and the other valve that sits next to the N429, it makes the bay look a lot less cluttered. Oh and Mr Greesha i disagree it is there to look pretty
A

though mine has changed now , i will be posting new pics tomorrow.

 

[CupraUK]

I didn't get round to doing mine today as it took me 4 hours to fit my TIP pipe I might do it tomorrow tho but I'm just wondering if its best to remove the box over the 4th coilpack or leave it on? I think I red on the golf forum its best to leave it inplace as unplugging it can cause problems?

Whats best you reckon?

I put it and the hose from the FPR into the glove box for now

 

[Cupra Ross]

I didn't get round to doing mine today as it took me 4 hours to fit my TIP pipe I might do it tomorrow tho but I'm just wondering if its best to remove the box over the 4th coilpack or leave it on? I think I red on the golf forum its best to leave it inplace as unplugging it can cause problems?

Whats best you reckon?

I don't think there's any point in doing the bypass if you're going to leave it there. That was my sole reason for doing the mod. My N249 is now completely disconnected from the manifold, therefore the N112 is also disconnected. I've removed the vacuum reservoir that used to sit awkwardly over the No.4 coilpack and the bracket that it sat on. Its in a ziplok bag in my garage.

 

[adam cupra 20vt]

Cheers for that I just wanted to be sure.......I'd rather ask advice from people that have done it then not know for certain and mess it up

 

[lc_allan]

I attempted to mine before, them one time use clips are an absolute ****.
There is no way I'm getting to the connector under the manifold so I'll be joining one part of the existing rubber to a new piece of silicone, to the top of the DV.
Just waiting on a in-line hose connector to arrive. I assume 6mm will be the right size if not I'll have a nice new brass one to throw at the monitor

 

[LEE69]

4mm usually