Hi
I had just switched coolant tank of my car. During the work I had to take the y pipe off and I saw that the electrical connector to the N75 was disconnected and placed in such a way that it can not have fallen off . I plugged it in and now it feels like I have 200 bhp less . The car charge 1.2bar as before, but it seems like it takes longer to build boost.

My question is, is there a mapping / chip or other proper reason for disconnecting power to the N75 ? Is it safe to disconnect it again?

I 've driven the car about 6000km and it works perfectly , but gets a little anxious in terms of overpressure without N75 connected. All vacuum hoses are connected to N75.

I have one ongoing lawsuit against the previous owner, so I can not just pick up the phone to ask ..

 

The car is a 2001 996 Turbo with X50 option

 

Only "reason" to disconnect that is to remove computer control and only use waste gate spring.. Not sure what base boost is on X50, what tune is on it?

 

Is there an electronic boost controller in your car?

 

I have no idea what tune i got, just told the car was about 600hp from PO. I disconnected the N75 again, and the car works 100% again. Fast and responsive... Strange? No other MBC or electrical as far as i know...

 

Do you have a durametric cable? If so, I would log the car to make sure that everything is working as intended with the N75 unplugged.

 

The tune is suspect if it does not function properly with N75 plugged in. The ability to control the boost level is one of the safe guards the DME has. Yours may be tuned and running just fine as is, but if you got a tank of bad gas or your fuel pump started getting weak your system is missing one of the safe guards. Also the sock system with the N75 controls boost as a function of throttle position causing the car to not seem as jumpy or radical with the HP hit at partial throttle. You don't have that without the N75, but maybe that's the way you like it.

 

no n75. that isn't right. i wish i could tell you what this tuner/shop is bypassing since it controls "boost" but "off"?!? is just NOT right. further thorough investigation is definitely in order. i wouldn't leave it disconnected at all. GL w it.

 

Even with that solenoid plugged in he will never get LESS boost than the W/G is tuned for. If he gets 1.2 with it disconnected then the W/G have been turned up, I wouldn't be surprised if the tune is trying for LOWER boost and can't do it so begins retarding timing or something else. Without the solenoid plugged in perhaps it's not as panicked? Either way, get a Durametric and get together with a tuner ASAP!

 

I didn't think X50 was an option until the 2002 MY?

 

Not true on the wastegate. A wastegate typically can run twice it's spring rate until the drive pressure in the turbine actually forces it open. If there was a direct like from the turbo to the wastegate Thrn it would run at wastegate spring pressure. Right now it is being fed no pressure.

Have you boost solenoid plugged in is important. I would suggest retuning the car with it plugged in.

 

Just a thought , can N75 hold WG slightly open if it is not working properly ?
It seems that the engine spends more time on charging boost when it is connected...


Either way it's a good idea to have it tested by a tuner!

 

There may be a manual boost controller in play somewhere. Check all the lines thoroughly.

 

Having the N75 pressure hoses connected but the electrical wire disconnected should send all the boost pressure to the wastegates, opening them at the spring pressure. If you're seeing 1.2 bar with the N75 wires disconnected, you have other issues.

 

Car keeps steady 1.2 bar with or without N75 ( electrician) connected. However , it use more time to reach 1.2 when disconnected, and the car feels like it lacks 200 hp.