n75 valve

[mygolfygti]

hi everyone.i was going to replace my n75 valve which i believe is the vw dump valve.i was wondering is a aftermarket one worth considering something like a bailey or forge?ive aloso heard of a n75j valve im not sure what this is tho.when i rang my local vw dealer up they said that it isnt call a n75.apparntly thats the fault code.any help would be gratefull...cherrs guys

[Crasher]

Presumably you have a 1.8T engine? The N75 valve is a solenoid that controls the boost by opening the wastegate on the turbo. The part you are referring to is what VW call a “cut off valve” and release pressure building up inside the charge air system on throttle closed overrun, sending it back into the system. The chav expression “dump valve” is reserved for those devices which replace the cut off valve and release the pent up gases into the atmosphere with an undesirable (in my opinion) noise. There are aftermarket recirculation cut off valves as well that avoid this noise. Unfortunately many of the aftermarket valves cause running problems, especially on the AGU engines but less so on the later models which had solenoid controlled ECU operated valves. The N75 on a Golf 4 GTI T is VW part number 058 906 283 F and VW dealers call it a “solenoid change over valve”. The N75J expression refers to the N75 valves used on some Audi Quattro models such as ones with the 3B engine and is VAG part number 034 906 283 J. These are commonly employed to improve boost but to be honest I have been unable to measure or feel any difference and I can’t see how they alter boost when they are just a computer controlled solenoid. They also stress the wiring due to the connection being the wrong way around so the wiring can need extending sometimes to suit.

[mygolfygti]

hi crasher thanks for the advice.my engine is the agu 1.8t golf mk4..so in your opinion having a blow off valve may well cause problems.i did get a price from the dealer for a new n75 and they said about 65 pound.maybe i should stick with that then.do you know what kind problems having a after market dump valve would have.also i read alot of posts about the agu.it seems to be that that is the engine not to have

[Crasher]

The AGU does not respond well to aftermarket “dump valves” and usually registers fault code “16486 - Mass Air Flow Sensor (G70): Signal too Low P0102 - 35-10 - - - Intermittent” within a few miles and is especially as problem on cars where the valve has been relocated to just in front of the throttle body, forum user Twign can verify this. There is nothing wrong with the AGU, it just isn’t as sophisticated as the later ARZ, AUM and AUQ engines and if worked on by someone who knows them, they are fine. What fault code have you been given from your car?

[mygolfygti]

hi crasher
well i havent had the car read from vw but i no someone whose got a diagnostic machine but in all honesty im abit wary about thr reports being acurate.the only fault code it come up with was a temp sender or sensor i cant remember but i did replace the sensor but i didnt go genuine i brought from euro car parts.its the blue plug type connector.i will however be replacing it with a genuine one and also replace the thermostat aswell.when my mate checked the n75 valve he did say it was working because he could hear it clicking.but i have a suspicion its tempermental.i also think my amm is faulty so thats gona be replaced too.i just seem to be experiencing power loss.one minute the car is flat on acceration the next minute its got abit of poke to it but even when it does it still doesnt feel pokey as it should.im hoping its not the turbo.i have got the car booked in next thursday to be inspected.so im hoping to shed more light on it.but before taking it in im hoping to hear from people like yourself who know the faults with these kind of cars...many thanks