Bypassing the N249 valve for a N75 racing valve?

MajinBuu^-^ · Jan 8, 2006

I found this on the web, does it really work? I didnt find anything regarding the N249 valve

http://www.peterbeers.net/vw_roadtrip/GTI/GTI_Mods/N75J/N75J.htm

Sim
08-09-2004, 20:27
The N249 valve controls the DV (Diverter Valve).

When you let off the gas, the throttle plate closes and vacuum is generated in the intake manifold. This vacuum opens the DV which releases air/boost which is generated by the spinning turbo.

The N249 valve is connected to a vacuum cannister (where vacuum is stored). When the ECU wants to release some of the boost during cruising or WOT (to decrease boost level) it uses the N249 valve to switch vacuum from the cannister to the DV when the engine is not generating any vacuum (because throttle plate is opened). It's working like the N75 valve, it is repeatedly opening/closing DV for short periods to settle boost level.

Removing N249 valve will prevent ECU to fiddle with the DV when cruising or at full throttle hence there will be a lot more smoother boost curve. Also N249 (the valve itself) works as a restriction in the line to DV. Without this restricition the DV responds faster. I like this mod. It gave completely new charasteristics to the engine.

On leons N249 is hidden somewhere near/below intake manifold.

ONE8T · Jan 8, 2006

I eliminated my N249 from the loop, but for different reasons. I haven't noticed any throttle or boost differences, but it definitely didn't hurt either. I removed it becuse it is the last line of safety when actual load values exceed spec values. Under these conditions it will open the DV. I already eliminated the boost sensor safety and had some jumpiness under WOT in the upper rpm range due to the load variations.:thumbup:

dutch-mountains · Jan 9, 2006

I have the N249 bypass for a year or so, no noticable improvements though. Having the DV directly connected to the manifold theoratically improves DV response, the faster the better.

dutch-mountains · Jan 9, 2006

Oh yeah, our N249 is located under the intake manifold, nice working area!

scotty_passat · Jan 9, 2006

have you guys been getting codes stored with the N249 bypassed?

dutch-mountains · Jan 9, 2006

None so far, btw I used a small tube with zipties to loop both vacuum connections to prevent dirt in the solenoid. The solenoid must be electrically connected, if not codes will follow.

ONE8T · Jan 9, 2006

dutch-mountains said:
None so far, btw I used a small tube with zipties to loop both vacuum connections to prevent dirt in the solenoid. The solenoid must be electrically connected, if not codes will follow.

Ditto.:thumbup:

modifiedA4 · Jan 9, 2006

btw, you should still provide the N249 with vac, basically Tee off the manifold with one lead going directly to the BPV, and one to the N249. plug the BPV lead from the N249. as mentioned, leave the N249 plugged in.

dutch-mountains · Jan 9, 2006

Why should vacuum still be provided to the N249? It is of no use anymore, the ECU still sees the N249 because it is electrically connected but has no more control over de DV. The front manifold vacuum outlet goes directly to the DV on my setup

modifiedA4 · Jan 9, 2006

dutch-mountains said:
Why should vacuum still be provided to the N249? It is of no use anymore, the ECU still sees the N249 because it is electrically connected but has no more control over de DV. The front manifold vacuum outlet goes directly to the DV on my setup

judging by this schematic, the vac line from the manifold also supplies vac to the combi-valve for proper actuation. (at least thats what it looks like to me)

MajinBuu^-^ · Jan 9, 2006

did anyone try the ECS N75 race valve be4? on their website, they claimed that it could add another 10hp, and 1-3 PSI.....

dutch-mountains · Jan 9, 2006

On my engine (APU) valve 16 does not exist. The U tube on the left of both valves is there but both connections are capped

Rusty · Jan 9, 2006

MajinBuu^-^ said:
did anyone try the ECS N75 race valve be4? on their website, they claimed that it could add another 10hp, and 1-3 PSI.....

N75 UPGRADE CAUTIONS - Read Before Purchase

damian856 · Nov 19, 2009

I know this is an old thread but I was wondering about this.... (I have an 03 FWD manual with GIAC, n75j and TT d/v) I've been thinking about doing this bypass mod for a while now but today just as I'm about to go out and do it, I stumble onto a page that says bypassing the n249 can cause higher spikes and LIMP MODE:thumbdown.... can anyone shed any light as to whether or not this would be a problem on my :b55:

nastynavy · Nov 26, 2009

modifiedA4 said:
judging by this schematic, the vac line from the manifold also supplies vac to the combi-valve for proper actuation. (at least thats what it looks like to me)

So I am looking into doing this and have a question....which is the N249 #16 or #23? I read the vwvortex writeup but it is a little different setup than my AWM I believe or I am just reading it wrong. Any help would be great. I have been getting a low boost code and I think this may fix my issue.
Thanks

dutch-mountains · Nov 26, 2009

#23 is the N249 solenoid. A low boost code could be a leak between MAF and MAP (on top of the IC #21) or the DV (#27) is gone.

nastynavy · Nov 27, 2009

Thanks Dutch. I will check that out as well. I have a Forge DV to install I was just trying to get the other issue fixed first but maybe that will fix it.

borislav98 · Feb 26, 2010

I have a 3 foot vacuum hose that fell off my 2000 Passat 1.8T when I was replacing the #034 PCV. I have been told it is most likely the hose that connects to the N249 nipple. Any advice as how to locate where the two ends go? Thanks.

Bypassing the N249 valve for a N75 racing valve?

MajinBuu^-^

ONE8T

dutch-mountains

dutch-mountains

scotty_passat

dutch-mountains

ONE8T

modifiedA4

dutch-mountains

modifiedA4

MajinBuu^-^

dutch-mountains

Rusty

damian856

nastynavy

dutch-mountains

nastynavy

borislav98

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