The N75 on a diesel is there to control blade pitch as you say but a diesel cannot technically overboost. A diesel engine takes a full charge of air regardless of the position of the accelerator pedal. I am pretty sure it is the N249 that is at fault. I would expect the same is true of Asian and domestic. I have a 2002 Audi tt Quattro 225 with chipped ecm and really no other mods. Or is it doomed to premature failure on a modified car running more boost than standard? Here is the link again: Also see search's for how code tags are performed. I thought I would keep it simple to get a feel for the forum rules and functions.
This solution seems to work well for me and it costs nothing. If anyone could inform me, i would me ever grateful Wouldnt mind having a go at doin it if its worth while. Is this not correct At the mo, ive bypassed the N249 but left the valve connected to the ecu but not to any vacuum pipes, hense no light on dash, I've left the one way valve and dump valve runs off manifold. I am wanting to test the N75 valve and N249. Would it make a stock car run crap or just no difference at all? An appropriate sized alu plate has to be cut, bent and drilled, which is then secured on the valve cover using the screws which was holding the original stuff seen above. So given that the issue was intermittent I figured it has to be something not always working as intended, also as performance varied it seems likely the problem is related to boost control somehow.
Open and closed throttle seem fine, just somewhere in between things seem different. . My N249 is now completely disconnected from the manifold, therefore the N112 is also disconnected. Referring to Robs diagram on www. Use cable ties rather than jubilee clips on the silicone hose you've fitted. The vacuum reservoir, N112, N249 on Leons are located elsewhere, but they look and work the same, so you probably can find them.
And if so, has anyone got a guide to bypassing it? Will it work as intended and help keep things smooth? A long wire has been soldered on the two ends of this resistor bank and all this has been covered with black masking tape The resistor bank is then secured to a loom in the car i've found and is hidden, so it is not visible to the unaided eye at all. The sharper dump sound is nice though. Do not block off the hose connectors that your removed, some people have tried it and had negative performance as a result well done mate, defo best guide ive seen. Here is a picture of mine after the bypass, as I said before remove the vacuum hoses from the sensors top left of pic, remove the black vacuum box they originally sit on bolt them down out the way keep them connected though or you will get error codes you could extend wires and hide them or replace with resistors but that's up to you, then remove the one coming from the secondary air system can just see this in the pic I just cut it just to the right of the dv, then route as in pic my be slightly different on the hose going to the fpr as I have my boost gauge teed off there. I have logged block 115 and seen desired boost is nearly double actual boost. Resistors are are fitted to all connecters that have been unplugged. Thinking it could be something to do with the N249 valve as i know a few people bypass it.
That's all, but all the crap around as the lack of expirience and correct tools makes it one really hard task. It all works fine although we did cable tie the pipes on to the t-pieces etc so may have to revisit it and replace the cable ties with small hose clips. Would anyone else say this is the case?? It is just making sure that the turbo cannot boost during coldstart. There are no boost connections to the N249. So for anyone who has done it, is it worthwhile replacing the valve on my car? It didn't throw up any fault codes with this problem. I suggest you to scan your codes to see why does it enter limp mode.
This is done so everyone can understand the config and how to contribute. You can then remove the hoses etc from the underside of the plate where the N249 number 16 in the diag and N112 number 17 valves are located. First thing would be the yellow spring as green is for standard boost I'm running max boost about 1. What adverse effects may this have if both the N249 and the N112 do not use the vacuum store? Yes, you're absolutely right - but we most of us are doing mods on our engines and judge the stock setup. Disconnect this and then re-connect it between the one-way valve and the other connection on the t-piece from the inlet manifold in step 6. . I have left the connector on the valve so as to not generate a fault code.
These spikes depend on N75 type, wastegate setting and software programming, but they usually don't last long 0. All content is viewed and used at your own risk. I have pretty much decided I am going to replace the valve with a new one, as much for my own curiosity as anything else. Thanks for the help, Shaun. I will post back my results when I get things done, and will look at some logs as suggested.
Clearly Audi fitted the N249 for a reason, and it seems like its main purpose is to make the car smoother to drive. Would anyone else say this is the case?? To do this, i have measured the resistance of the N249 valve, which is 30Ohms. The N249 system connection is not so much a vacuum source as a pressure sensing connection. Practically you have now completed the task! Running high boost and lean mixture may have though. Before after graphs Proceed at your own risk! Even though you've removed the secondary air system you should still let the car warm up for 90 seconds before driving away as there is another part to the cold start process that is still working, the variable valve timing which keeps the exhaust valves open for slightly longer than normal until the cold start process is finished. Yes it would not make any difference. I have got this setup working now on my car for almost 2 months without any problem.
I have heard nothing but good things about this site and the people participating. I was thinking maybe I could get some input on the methods used to perform these tests. This vacuum comes from the intake manifold or the vacuum reservoir via the N249. So the real point of having the N249 is that it allows the control system to react quicker to protect the engine from overboosting the turbo in a 'tip in' or wide open throttle condition?? The car in general runs better apart from when cold. We want to keep this feature as it has nothing to do with performance so we have to put the N112 back to its original place. In its un-bypassed state, the N249 is just that, well a conduit in the vacuum source if you like. This is what the black vacuum reservior on top of the engine is used for.
Just check out my photo above. Petrol engines are completely different in this respect. Not un-driveable by any means, just not as smooth as it used to be either. When the car is cold the car trys to over boost even on slight to no throttle. Pulling a little airflow from the process is likely to create more lag between gear changes, even if its such a small amount you don't notice it. So people have an idea of what's going on here. You may use any setup, but be sure not to use less than ~30W, and make sure it has got a resistance of 30-33Ohms.