sudden loss of boost?

[h100vw]

Okay I brought the car into Camden GTi and they told me I should replace the n75 and if that doesnt work the turbos stuffed. I also just got a VAG-COM cable off one of my mates but i have no idea how to use it. I did a scan and got a temp sensor fault and that's pretty much it. How can i use the Ross-tech software to try and diagnose my problem? I read somewhere that you can log requested boost then actual boost but i cant seem to find how to do it. Or even like a MAF reading because my fuel economy been down as well, then ill post it up here and get someone more knowledgeable to tell me what im looking at.
Thanks

You can't log boost on a MK4 in australia, it doesn't have a MAP sensor.

You can see MAF output.

Is it a proper VCDS cable?

Gavin

[Anth1223331]

You can't log boost on a MK4 in australia, it doesn't have a MAP sensor.

You can see MAF output.

Is it a proper VCDS cable?

Gavin

Ah okay. Yeah its a genuine Ross tech cable.
Thanks

[Anth1223331]

Well... Ordered a new OEM n75 and fitted it today, made sure it was orientated correctly and all that, and got even LESS boost... approx. like 5 maybe 6psi. I was testing my old n75, and while the valve is closed, if i blow hard enough through the long outlet that goes into the TIP a tiny bit of air leaks through. When i blow through the new one its completely air tight but it gives me less boost... So i'm just gonna run the old one for now.

[theBRUCEofWAYNE]

Well... Ordered a new OEM n75 and fitted it today, made sure it was orientated correctly and all that, and got even LESS boost... approx. like 5 maybe 6psi. I was testing my old n75, and while the valve is closed, if i blow hard enough through the long outlet that goes into the TIP a tiny bit of air leaks through. When i blow through the new one its completely air tight but it gives me less boost... So i'm just gonna run the old one for now.

I had the same experience. Bought a brand new OEM N75 from ECS. Car boosted about 1 psi less. Got a used one from an Audi and got the 1 psi back. You got an analogue or digital boost gauge? I forget.


Sent from the Batcave

[Anth1223331]

I had the same experience. Bought a brand new OEM N75 from ECS. Car boosted about 1 psi less. Got a used one from an Audi and got the 1 psi back. You got an analogue or digital boost gauge? I forget.


Sent from the Batcave

Yeah such a waste of money :'( I've got a mechanical guage t-ed into the FPR vac line

[h100vw]

https://www.google.com/search?q=n75+...M-opyw3uYcM%3A

Just check it's fitted in the correct orientation. As the boost sounds like its on actuator pressure still. A difference of 1 PSI doesn't covince me that there's a difference between the 2 that you have tested.

Gavin

[Anth1223331]

https://www.google.com/search?q=n75+...M-opyw3uYcM%3A

Just check it's fitted in the correct orientation. As the boost sounds like its on actuator pressure still. A difference of 1 PSI doesn't covince me that there's a difference between the 2 that you have tested.

Gavin

Yeah thats how I had it orientated, It was $60 of ebay so its probably just a dud, theres no product number or anything on the actual valve itself so yeah. What you get for going cheap I guess. Thanks everyone for your help, ive been thinking of eventually upgrading to a K03s so i guess ill be getting it earlier rather than later than see what happens from there.

[schwartza3]

hey mate, you should get this sorted before upgrading the turbo as the issue doesn't seem to be coming from there.
I mean, you proved it can make up to 17psi with N75 to wastgate line clamped.
Since you got the vag-com why don’t you do some logs and post them on here, the issue could be as simple as a bad maf, the agu engine relies heavily on the maf readings as it doesn't have a map sensor and can't see boost as Gav mentioned.

[theBRUCEofWAYNE]

Shouldn't be a dud. You can't really install the N75 the wrong way, cos the wiring clip and loose 2 pipes won't reach. Longest fitting on the N75 goes into the intake, the opposite one connects to the wastegate line.


Sent from the Batcave

[Anth1223331]

hey mate, you should get this sorted before upgrading the turbo as the issue doesn't seem to be coming from there.
I mean, you proved it can make up to 17psi with N75 to wastgate line clamped.
Since you got the vag-com why don’t you do some logs and post them on here, the issue could be as simple as a bad maf, the agu engine relies heavily on the maf readings as it doesn't have a map sensor and can't see boost as Gav mentioned.

I can try and do a log haha don't really know what I'm doing though. I know how to log on the program but do I just WOT from low revs in 3rd or something? If someone could fill me in on what to do that would be great.

I'm sure it was orientated properly so that wouldn't be the problem. I'm getting the wiring professionally done soon with a new plug as at the moment it's soldered quite poorly as they were cut when I bought the car. But when I was talking to an electrician I know, he said it would still work and shouldn't be a problem but it's just not strong kind of thing. This should be done within the next two weeks and I can rule out/find my problem.

Thanks everyone for the responses.