Hi all,

I did the N249 bypass on my car on Sat and then did the long drive to Glasgow and back this weekend and so I have some thoughts on this mod.

I was originally led to this as I needed to solve a DV problem I was having, the error I was getting was "N249 mechanical malfunction" but that error can be the cause of either an N249 valve fault or another fault in the DV vac system.

In my case the fault was the DV but having read up about the N249 bypass, I decided to try it anyway......

My thoughts so far are:

Pros - Car seems to drive smoother, I'm not getting the low speed jerkyness I used to get and also the DV only seems to open on backing off the throttle rather than sometimes opening on part throttle.

Can clean the engine bay up some more by removing vac reserve and vac lines.

It also seems to be boosting a fraction higher, 0.2 Bar and it held boost right up to the Red line (but on my car that isnt a good thing as I saw a figure of 1.8 Bar on part throttle overtaking which cant be safe?)

Cons - Crazy boost level, not sure it is safe?

Boost is no longer limited by the ASR and so when it was wet on my way back, she was a real handfull when the wheels spin. Not a massive problem for me but my wife also drives this car and I dont think that was safe for her.

I'm gona leave this as is for the rest of the week but so far I'm not sure I like it. I can see that with a K03s car where I might be wringing every last bit of boost out of it then it could be cool but on my car power isn't the problem as this mod makes the car less drivable in my view.

Ron

It's a bit of a debatable one really.

I did the bypass on my mates K03S VRS a couple of months back after his N249 gave up the ghost and he raves about how smooth it is now, he is only running a remap which peaks at about 19psi (1.35bar) and settles to 15psi though so not really any issues with overboosting.

I would do it on mine but the only thing that bothers me is it is one of the options the ECU has to control things if it needs to stop the turbo providing boost (or if it's overboosting uncontrollably), if you remove it then you lose that extra "safety net" and if the turbo does start overboosting you are only relying on the N75 and wastegate to function properly and sort things out.

Yeah thats pretty much my concern too. Also if it aint broke then why fix it.....the car drove fine with the n249 just was a little jerky some times but nothing you'd actually think was out of the ordinary.

I did this mod and got rid of the n112 at same time as not got a cat. My car tends to run cak for 1st 90sec then after that she pulls all day long and is smoother. Awesome put me a stage 2 apr map on it last month and it hits 23-24psi and settles at 20 but never higher than 24. But never had a problem with the car being unsafe on the road. If i'm going to do any hard driving the asr always gets turned off. I dont trust it, as it kicked in once as i was correcting a slide on a corner. It cut the power and I didnt like that as nearly lost my baby. I guess it's all down to how you drive or want to drive, if a mod suits you or not.

my cars runs fine after doing this and a whole lot smoother, both when it had the shark stage 1 map and now without the map (which was removed ready for it to be sold). never had issues on start up or with it over boosting and its never been un safe while driving

It's a bit of a debatable one really.

I did the bypass on my mates K03S VRS a couple of months back after his N249 gave up the ghost and he raves about how smooth it is now, he is only running a remap which peaks at about 19psi (1.35bar) and settles to 15psi though so not really any issues with overboosting.

I would do it on mine but the only thing that bothers me is it is one of the options the ECU has to control things if it needs to stop the turbo providing boost (or if it's overboosting uncontrollably), if you remove it then you lose that extra "safety net" and if the turbo does start overboosting you are only relying on the N75 and wastegate to function properly and sort things out.

how many safety devices do you want lol n75 and wastegate not enough??????? madness

as long as you have the correct spring loadings in your dv for the maps you have then you should not see any overboosting so i suggest you have a play with some shims in the dv to get the setup coorrect

I dont know.....I used to be in the balls out racinf performance camp before I got married and hads kids

I have the Yellow spring in mine forge DV.......

Other than that it runs pretty much the same as it did with the N249 apart from when the ASR kicks in. For me when I'm giving it some I have it turned off but with 300 bhp in the wet for my wife, I'd rather the N249 was there to back off the boost if there was trouble.

I dont think there is a right or wrong conclusion, just that in my case it wasnt broke so all this has done is removed a safety device.