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The correct way to do an N249 bypass the full guide

Discussion in 'Mk1 Leon Guides (1M) 2000-2006' started by mc funbot, Jan 18, 2013.

  1. mc funbot

    mc funbot its a beast its got boost

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    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 cat back exhaust an a air filter.this took me 25 mins to do.that was with taking photos and telling the lad what i was doing..

    lets get started this is simple and a great mod ive done it to all my 1.8t cars from standard mk4 golfs to my mk3 ibiza at 340bhp

    tools needed
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    this is what you will start with
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    this is what you will have removed
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    your work is good now reward your self with a beer and a pat on the back!
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    this is all the rubbish that you should have removed..
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    i hope this helps you guys an ive never had any problems just improve ments not engin lights on..
     
    Daz1.8T and Barry Whittle like this.
  2. mc funbot

    mc funbot its a beast its got boost

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

    Rgm racer Active Member

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    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?
     
  4. mc funbot

    mc funbot its a beast its got boost

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    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.
     
  5. Rgm racer

    Rgm racer Active Member

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    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?
     
  6. mc funbot

    mc funbot its a beast its got boost

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    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
     
  7. Rgm racer

    Rgm racer Active Member

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    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??
     
  8. mc funbot

    mc funbot its a beast its got boost

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    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?
     
  9. mc funbot

    mc funbot its a beast its got boost

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    Where you from I'll use your car for a guide ;)
     
  10. Rgm racer

    Rgm racer Active Member

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    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;)
     
  11. mc funbot

    mc funbot its a beast its got boost

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    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.
     
  12. Dante L2A2

    Dante L2A2 Active Member

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    Cool guide is there any risks in doing this
     
  13. mc funbot

    mc funbot its a beast its got boost

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    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.
     
  14. Dante L2A2

    Dante L2A2 Active Member

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

    mc funbot its a beast its got boost

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    If you need any help just ask.
     
  16. NRM 90

    NRM 90 Active Member

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    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.
     
  17. mc funbot

    mc funbot its a beast its got boost

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    Hahah not a problem ;)
     
  18. dazjstuart

    dazjstuart Active Member

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    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.
     
  19. mc funbot

    mc funbot its a beast its got boost

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    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..
     
  20. Mk1 banana

    Mk1 banana Active Member

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

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