Hi there. Tried to search the forums for N75 problems, but the search engine dont allow me to search for a short word(3 letters).

I have an Audi a4 b5 1.8t quattro. Suddently i lost power, and it feels like im driving a non-turbo car. I can hear the turbo spooling up, and when i release the throttle at 1500rpm to 3000rpm, i can hear some kind of dump valve sound, even if its stock dump valve(?). Over 3000rpm the dump valve stops.

I`m from norway, so i dont know what you call these sounds, but its like a fast "chu-chu-chu" , not "phish"... Well, im rather bad in english AND explaining, but I hope you get what i mean

I suspect it might be the N75 valve thats stuck open, so the turbo wont give any power to the engine.. How can i test this theory? Anyone have any other suggestions? I do not have a VAG-COM, and a dealer charge about 250 USD to read code.

Best regards Stephan, Norway

 

The "dump valve" you are referring to is called a diverter valve. It's possible it is failing, pretty easy and cheap to replace. I would recommended you upgrade to the 710n diverter valve instead of a factory one as it is just a bit more but it is more powerful so to speak

 

Its possible the n75 is bad, or the diverter valve is bad, or you are in limp mode. best thing to do is hook up a boost guage to see what the boost level is and we can go from there. its tough to diagnose these things without that info

 

Thanks. So you think this will fix the problem?

I heard that if i unplug the top valve on the N75, i can see if the N75 is the problem or not? I know it will keep the diverte valve shut, but luckily im not an idiot(?), so i wont go WOT. Its just too see if i get the boost higher than 0.3-0.4 bar.

I hooked up a boost gauge, and i get 0.3 to 0.4 bar. One thing i think is strange is that i get the DV-sound from 1500rpm, in every gear. Shouldnt it be higher?