i hear there are problems with the standard n75 valve, and also with fitting after market atmospheric bov's. so does anyone here run a dual port type?
The N75 valve is the boost/wastegate control valve. The standard units work fine. The reason you here about them is that you can often swap them for a different version of the valve from another VW/Audi car to give extra boost. You shouldn't run atmospheric DVs on a VW/Audi car as the ecu is expecting to see the recerculated air from the valve and gets upset if it doesn't see it, thus problems etc. Not sure about duel port jobbies, but surely the ecu will still be reading the wrong amount of recurculated air. You just after the noise?
is there anyway to modify the ecu to see no probs? i've never heard of such probs with other manafacturers?! i just thought it'd be a happy medium, low revs and boost- normal, high revs and boost- chav!
and i thought people replaced the n75 with the metal jobbie from tt's 'cos the plastic one is unreliable!
what me and harry just said is basically, you have no real choice but to run a re-circ/closed loop bov. as atmospheric dv's cause the ecu to go mental. there is some noise on re-circ's but not alot, i'm not even sure if theres meant to be any. you might get a "chatter" noise which i always led to believe it was meant to make, but apparently this is a sign of your diverter valve/wastegate knackered, or along those lines. harry knows more (please stpe in)
as far as i know the std one works fine. but if you plan to mod it then i think an aftermarket one is a good idea if you plan to boost more. turbosmart, bailey etc make good re-circs.
If your standard DV makes a "chatter" noise when you lift off the throttle, then its f**ked and won't be holding full boost. You can replace it with another standard one or an after market recirculating DV, your choice, but the standard one will fail again after a while. (I've got a Forge item on mine). Wez is correct in saying, if you are planning to chip, then you need a better DV. If you really have to have the "noise", then you can remove the stock airbox and fit an induction kit. A proper one where the filter is sealed from the engine bay and not one that uses oil as it will coat your MAF sensor and mess that up too. The quickshift one from here is the best. Edited by: harry_the_cake
didn't you have an issue with you std n75 valve harry? did you replace it with the J item in the end? i hear that it does boost more- that true?!
No, my N75 is fine, I had a prob with my standard DV too. The J valve doesn't work for all cars. It seems to work fine on non DBW engines with code AGU, but causes overboosting on some later engines. You just have to try it and see. If your car overboosts, then it'll go into limp home mode and limit the boost (a real pain as the car runs like poo). You then need to reset the ECU via VAG-COM, or visit your local dealer. [:^(] Doesn't damage the engine, just hassle. Bare in mind that the N75J adds a little extra boost, but does not add extra fuel, but it should be fine for the amount added. Personally I'd just swap the DV for a Forge item, get the air intake for the noise and chip it, and you'll have a pretty nippy car. Edited by: harry_the_cake
dv being diverter valve, which is just vw's way of caliing it a dump valve- its the re-circ isn't it! just so everyone knows lol
also- the plan is a good one H, but the reason people exchange the std n75 valve is becuase after chiping people are getting boost surge, which is why the need for the n75 valve upgrade, the J being the best bet with a chipped car with other variations from other models working better with other mods if problem occurs not just after a chip. so do you replace it first, or chip it and if the problem arises adress the issue or buy an aftermarket boost controller as the J is also said to spike to over 20 psi which cant be good, but on a good point holds boost very well.
You are correct in saying the J version is a bit smoother. If you fit the J version and then go for a custom remap like Jabba offer then they can take into account the extra boost from the J when they remap it. Yeah I do mean recirulation type when I say "DV".
also, that wouldnt stop the spiking, the boost is controlled by the ecu sure, but the n75 J is designed for the TT isnt it at higher boost levels and as it's a solenoid is what makes it possible to leak, so a mbc is really needed instead to stop these problems, if the chip has already been done.
Mines only got the forge DV at the mo. But a good friend of mine (same car) has the mods I mention. He doesn't seem to have the cash flow problem that I have at the mo [:^(]
