If the n249 valve is playing up would that affect the boost and performance

If the n249 valve is playing up would that affect the boost and performance

Yes potentially. The N249 is what controls the opening of the DV so if it's faulty it could be keeping the DV open when it shouldnt be, by using the vacuum reservoir. That would mean a proportion of the boost would be getting lost through the DV instead of going into your engine.

Your DV should make a "tssch" noise when you lift off although this will be hard to hear if you've got a standard valve or no CAI. If it's not making the "tscch" noise at the point of throttle closure, then the DV is already open (which it shouldnt be).

You can bin the N249 if you want and just run the vacuum hose straight from the DV to the inlet manifold that way when there is a vacuum in the manifold (when the throttle is closed) the DV will be pulled open without the N249 interfering.

As Clive said try and log the actual vs requested boost before you replace or remove the N249, if the two match then the cars been put back on the standard map, if they don't match then it could be the N249, N75 or DV at fault if you're sure all the vac hoses are ok.

If the N249 is goosed you should get a 17608 code come up anyway. And if the actual boost is way off what the requested boost should be, you should get the good old 17705 code.

By the way where is your boost gauge getting it's feed from, fuel pressure regulator?

By the way where is your boost gauge getting it's feed from, fuel pressure regulator?

Yeah boost gauge is conected to the fpr. Had the fault code 17608. and 17840 which is being sorted tommorow

Does sound like the N249 then. RobClubleys site has a good guide on removing it unless you want to buy another one.

Just been looking at robs guide looks pretty straight forward. Apart from the n122 pipe thats connected. What do i do with that. All i want to do is disconnect for now until i get a new valve. Cheers guys

In Robs guide he's removed the secondary air injection system at the same time so the N112 is removed too.

We did an N249 bypass on my mates VRS and I'm pretty sure he still had the secondary air system on, I think all we did was remove the T-piece between numbers 16 and 7 on the diagram, replace it with a straight bit of pipe, and then re-route the vac hose that went between the inlet manifold and that t-piece so it went straight between the manifold and top of the DV. We then blanked off the old hose that used to go to the DV.

The N249 was left in place so it could still supply a vacuum to the N112 and secondary air injection system but that was going to be removed at a later date anyway - all we'd done was take away the N249s involvement in the turbo control.

Will have a go at the weekend. How did u blank the old dv hose off

Put a bolt in the end of the hose and used a small one of these to keep it in place:

http://www.cbsonline.co.uk/product/Stainless_Stell_Fuel_Hose_Clips_13-15mm_SFHC13

Cheers for all your help mate.

No probs.

Sorry for the crap diagram but I think this is how we did it:

You can see now the DV works straight off the vacuum from the inlet manifold but there is also still a feed to the vacuum reservoir etc. so the N112 can use it when it needs to for the secondary air system.

Of course, it's a lot simpler to just bin the secondary air system off at the same time, then you lose the vacuum reservoir, N112, secondary air pump and combi valve too. :yes:

Do i still put a straight pipe inbetween 16 n 7

No straight piece - sorry, that was my error. If you put a straight piece in then you would lose the vac feed from the inlet manifold to the loop between the vac reservoir (13) and the N112 (17) so that would mean your secondary air system won't work properly on cold starts.

Just put a t-piece into the hose from the manifold as per my last post so you have one vac feed to open the DV and the other vac feed still going into the loop mentioned above. Then blank off the old pipe that used to go between the N249 and the DV.

Or remove the secondary air system at the same time as per Robs guide, but you need the Forge blanking plate to do that:

http://www.forgemotorsport.co.uk/content.asp?inc=product&cat=010101&product=FMEGRBP

Well ive done the n249 bypass no difference. Put the original ecu on boosting the same but the car feels slower. Also on start up the boost gauge needle bounces for a bout 30secs. Im really starting to pull my hair out now :’(

N75....

Steve

does the car idle rough ?

does the car idle rough ?

A little yeah. Only on start up

Edited 28 January, 201214 yr by gav c

why do people choose to do things the hard way!!!!

find someone local with vag com and log boost etc etc you will instantly be able to see where the issue is ;-)

if it pulls hard then i suspect its your boost gauge thats crap but this would be ruled out if you just stick vag com on the car !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

It was the ecu that was at fault.... Fitted it to mine and only boosting 6-9psi and felt flat as a pancake

Wierd - new ECU time then? :(

As everyone keeps saying, get the fecker on vagcom and see what the problem is!!!

wrc, did you try fitting your ecu to the op's car? did it help?

As everyone keeps saying, get the fecker on vagcom and see what the problem is!!!

wrc, did you try fitting your ecu to the op's car? did it help?

I had it logged with vagcom while on my car there is nothing wrong with the ecu it's just oem??? Not mapped at all.. The file was coming back as a oem file too...

What I think in all honesty is the seller of the stage 2 ecu removed it from his car to sell and the had the immobiliser removed which has wiped the map clean and re wrote it with a oem map but with no immobiliser

Ahh, makes sense.

Is it only requesting OEM boost levels etc.?

Ahh, makes sense.

Is it only requesting OEM boost levels etc.?

yes that's correct. It's a full working ecu but oem,