What conditions will stop N75 operation?

[UrS4boy]

100% sure its a brand new conversion all the vac pipes are new and secure.

Okay. I'll just sit by and

[Rusty]

MFTS DOES affect boost on an ABY. Rustynut had this . Unplug the MFTS and take it for a quick run

[prj]

I am assuming the N75 is not getting a signal from the ecu to change state, there is 12v at the plug when the car is running but it doesnt change state when the throttle is opened.

That's expected behaviour, the N75 is ground triggered. There will always be 12V on the positive pin.

[UrS4boy]

That's expected behaviour, the N75 is ground triggered. There will always be 12V on the positive pin.

Hmm...Is the S2/RS2 different than the C4 UrS4/S6? With the UrS4/S6s, as shown below, the power to the N75 Wastegate frequency valve (WGFV), the N71 Idle speed stabilization valve (ISSV or ISV) and the N80 Evaporative Emissions control valve all come through the S75 12Amp fuse which, in turn, only gets its power feed once the J17 fuel pump relay is energized. That only happens if the engine is turning more than 13 RPM (e.g. during starting a weak battery that does not achieve 13 RPM cranking speed will never start an AAN).

[Pirvu Eugen]

Sounds stupid...but you have checke'd the n75? Is not enough to just hear making click.....should close the wastegate hose terminal with 12v applied. I had more than 5 valves wich made the click noise but the wastegate hose was still receiving boost pressure.

[UrS4boy]

Hmm...Is the S2/RS2 different than the C4 UrS4/S6? With the UrS4/S6s, as shown below, the power to the N75 Wastegate frequency valve (WGFV), the N71 Idle speed stabilization valve (ISSV or ISV) and the N80 Evaporative Emissions control valve all come through the S75 12Amp fuse which, in turn, only gets its power feed once the J17 fuel pump relay is energized. That only happens if the engine is turning more than 13 RPM (e.g. during starting a weak battery that does not achieve 13 RPM cranking speed will never start an AAN).

Found this 3B ECU schematic at Paul Nugent's website. The fuse number is different but the principles are the same as the AAN:

[pasbogdan]

Sounds stupid...but you have checke'd the n75? Is not enough to just hear making click.....should close the wastegate hose terminal with 12v applied. I had more than 5 valves wich made the click noise but the wastegate hose was still receiving boost pressure.

If i think exit from n75 to wastegate will not be closed.Just exit to turbo inlet opened.

[prj]

If i think exit from n75 to wastegate will not be closed.Just exit to turbo inlet opened.

Correct.

@OP
Also, if you have not done boost leak test, you will have boost leaks.
I don't care who you are or how highly you think of your work... If I come to your car with a boost leak test kit, I know at least two places off the top of my head that will 100% leak.

[a4kquattro]

Correct.

@OP
Also, if you have not done boost leak test, you will have boost leaks.
I don't care who you are or how highly you think of your work... If I come to your car with a boost leak test kit, I know at least two places off the top of my head that will 100% leak.

idle stabilizer valve and pcv vent 't' below the intake.

What do I win?

[kingfishers2]

Thanks for all your help on this so far, i have had no time to investigate further but plan on looking at the weekend.

Dimitri, Your welcome to come to my house with your extra special boost leak test kit im sure it will be better than anything i could ever own or use, i would also like you to cast your god like eye over the unfinished wiring loom that you disapproved of as it is now finished, i'm scared to hand the car back to my friend before it has your seal of approval. As i'm sure it wont be good enough.

[Pirvu Eugen]

If i think exit from n75 to wastegate will not be closed.Just exit to turbo inlet opened.

Yes! Sorry! My bad...but the ideea is that the solenoid is not working mechanicaly and will not throw any codes.

[prj]

Dimitri, Your welcome to come to my house with your extra special boost leak test kit im sure it will be better than anything i could ever own or use, i would also like you to cast your god like eye over the unfinished wiring loom that you disapproved of as it is now finished, i'm scared to hand the car back to my friend before it has your seal of approval. As i'm sure it wont be good enough.

Aww, why so emotional?
You haven't pressure tested the car - so do this first.

Not sure which wiring loom you are speaking of though.

[Rusty]

Is there a stamp that you can get with 'prj approved' and a big tick on it