The correct way to do an N249 bypass the full guide

mc funbot · Jan 18, 2013

Guide now located in the new resources section of the site

Engine bay - N249 Bypass - A complete guide

hey guys and gals after having a slight debate over the way to do an n249 bypass this is how i would do it,i like to know your views on it.i see alot of people only doing half a job.a random guy with a 1.8t leon agreed to let me do this.it had a...

www.seatcupra.net

mc funbot · Jan 18, 2013

Can people give me a little feed back on this. Simple enough?easy to do? Will you try it? Post pics up?

Rgm racer · Jan 18, 2013

mc funbot said:
Can people give me a little feed back on this. Simple enough?easy to do? Will you try it? Post pics up?

Is there any extra pipe required here or are you just making use of what is already there?

In last couple of pictures i see there is a pipe [not too far from dv] with no hose or end on it?

What improvement/s do you find with this mod, any down sides/potential down sides at all and you say you don't get any dash lights or fault codes?

Finally, any reason you can think of not to do it on a big turbo conversion used for track days?

mc funbot · Jan 19, 2013

It's well worth doing it improves throttle response and dv response. You don't get any fault codes or lights due to using the n249 resistors.ive done this on my big turbo conversion running. 340bhp. You need about a metre of pipe that's all. The pipes that you see with no pipe on are the ones from the pics further up. Just the old dv pipe and black box pipe. If you do The SAI REMOVAL all of that's goes on the Leon it's all hard metal pipe so it's has to stay other wise. Your more than welcome to come round and ill talk you through it. I'm from Northampton. Anything else I can help with pal just ask.

Rgm racer · Jan 19, 2013

mc funbot said:
It's well worth doing it improves throttle response and dv response. You don't get any fault codes or lights due to using the n249 resistors.ive done this on my big turbo conversion running. 340bhp. You need about a metre of pipe that's all. The pipes that you see with no pipe on are the ones from the pics further up. Just the old dv pipe and black box pipe. If you do The SAI REMOVAL all of that's goes on the Leon it's all hard metal pipe so it's has to stay other wise. Your more than welcome to come round and ill talk you through it. I'm from Northampton. Anything else I can help with pal just ask.

What pipe do you recommend/use and do the old dv and black pipe not need blocking? Where do these "open"pipes now lead to if not to dv and black box?

mc funbot · Jan 19, 2013

Use 4mm vac line can get it of eBay. The metal open ends are metal sleeves to dv and black box they only go from 1 end to another that's all. So no vac leaks etc. it's all built in to the Sai/egr so can't be be removed unless you take if Sai and blank it. Ill get pics

Rgm racer · Jan 20, 2013

Other thing I see people talk of removing are SAI and EVAP, what are these/what do they actually do and what's your thoughts/opinion on removing them??

mc funbot · Jan 20, 2013

Sai is secondary air injection it's a pump at the front of your engine at the bottom! It's a pump that runs from 60-90 seconds to warm up your cat in your exhaust. They can split or crack an put up a fault code that's why we remove. Or running a decat you can take it out. I will be doing an Sai guide in the next week or so. EVAP is carbon canister. They are fitted to help emotions but pointless after 3-4 years as they don't work. Can be taken out aswell. Simple to do. I can do a guide for that aswell.. Hope that helps?

mc funbot · Jan 20, 2013

Where you from I'll use your car for a guide

Rgm racer · Jan 20, 2013

mc funbot said:
Sai is secondary air injection it's a pump at the front of your engine at the bottom! It's a pump that runs from 60-90 seconds to warm up your cat in your exhaust. They can split or crack an put up a fault code that's why we remove. Or running a decat you can take it out. I will be doing an Sai guide in the next week or so. EVAP is carbon canister. They are fitted to help emotions but pointless after 3-4 years as they don't work. Can be taken out aswell. Simple to do. I can do a guide for that aswell.. Hope that helps?

Thanks for reply.
So why in theory does the cat originally need to get warmed up by this for the 60-90 secs and does removing it have no negative effect whatsoever?

Same for carbon canister what is it actually supposed to do and again no negative effect at all after removing, short or long term?

Another one I just spotted people talk of removing is N112, what's this for and again definitely better without/not needed??

Would any of these mods throw up a permanent EML light or fault code causing any issues etc?

I'm in Yeovil Somerset so fair trek from you.
I'm all for simplifying the engine and definitely losing any weight however small as mine is basically a stripped out road legal track Leon. Maybe if we could get together at some point and in return for your help I'd invite you along to a future track day and take you out for some laps

mc funbot · Jan 20, 2013

I don't mind sorting something out. As for track days will you keep up

? Haha. The n112 gets done on the n249 it's 1 of the valves in the guide. As for the carbon canister Bo faults on any of the cars I've done. It just collects fuel vapor that's all. Just need to leave the top of the can plugged in an chance wire back. That way it will still perge if needed.. If you have a decat it's not needed at all. No problems taking the SAI you can trick it with a 330-10w resistor. I have no lights on at all and all if Myn are gone on all of my cars.

Dante L2A2 · Jan 30, 2013

Cool guide is there any risks in doing this

mc funbot · Jan 30, 2013

Nope you are totally fine I've ran the bypass in my car for over 3 years now and it's been fine. Same on all my 1.8t. It's simple to do and a good improvement.

Dante L2A2 · Jan 30, 2013

Might have to look at doing this once the weather lets up.
Thanks

mc funbot · Jan 31, 2013

If you need any help just ask.

NRM 90 · Feb 4, 2013

Bypass and SAI done thread was a good help wish I read all of it now then there would of been no need for the ridicules text lol sorry fella.

Well surprised at the difference it made much mure responsive.

mc funbot · Feb 4, 2013

Hahah not a problem

dazjstuart · Feb 9, 2013

Thats a really good guide mate, I'll give that a go sometime. The last pic is particularly great when you lay it all out the way it should go on the floor. I have seen another guide on how to do this that was pretty good but your pictures and explanations of where things go is much clearer.

Just to get this clear, you literally just plug the N249 valve and the other one (N112?) on that plate by the dipstick back in, with no pipe work attached to them and it all works fine?

If you could do an SAI removal one that would be great.

mc funbot · Feb 9, 2013

yes mate plug them back in its fine its better than resistors some people say.. any problems just ask.. ill be doing a SAI guide soon dont worry..

Mk1 banana · Feb 14, 2013

Good guide mate, ill be doing it in my lunch brake

The correct way to do an N249 bypass the full guide

its a beast its got boost

its a beast its got boost

Active Member

its a beast its got boost

Active Member

its a beast its got boost

Active Member

its a beast its got boost

its a beast its got boost

Active Member

its a beast its got boost

Active Member

its a beast its got boost

Active Member

its a beast its got boost

Active Member

its a beast its got boost

Active Member

its a beast its got boost

Active Member

Similar threads