How would a bad N75 valve affect requested boost?
#1
![Default](https://www.audiworld.com/forums/images/icons/icon1.gif)
Here is an AWE stage 3 OTS requested boost graph:
<img src="http://img.photobucket.com/albums/v654/DocSlow/AWEStage3OTSRequestedBoostCurvePSI.gif">
As you can see, the requested boost is quite low compared to what AWE claims their kit usually runs. Somebody suggested that this could be caused by a bad N75 valve since the car has been checked very thoroughly for boost leaks, but I don't understand how either a boost leak or a bad N75 would affect the software's requested boost curve like this.
<img src="http://img.photobucket.com/albums/v654/DocSlow/AWEStage3OTSRequestedBoostCurvePSI.gif">
As you can see, the requested boost is quite low compared to what AWE claims their kit usually runs. Somebody suggested that this could be caused by a bad N75 valve since the car has been checked very thoroughly for boost leaks, but I don't understand how either a boost leak or a bad N75 would affect the software's requested boost curve like this.
#5
AudiWorld Expert
![](https://www.audiworld.com/forums/images/ranks/guru2.jpg)
![Default](https://www.audiworld.com/forums/images/icons/icon1.gif)
We've seen limp mode give low N75 DC (appropriately), but Requested Boost is still at it's normal values.
Again, this if from just one experience, so I don't know how other limp modes affect Requested boost - just sharing this encounter
Again, this if from just one experience, so I don't know how other limp modes affect Requested boost - just sharing this encounter
#6
![Default](https://www.audiworld.com/forums/images/icons/icon1.gif)
So not knowing what your graph looks like.. I'll tell you a little story.
When I had GIAC X, my requested boost was consistently .3 bar below actual. The actual boost was at the correct level (18 psi taper to 11ish). This is with a new N75. I always thought it was weird, and I didn't get throttle cut. I then ran APR software for a while, and requested and actual were spot on, and the levels were the same as the actual I got with the GIAC X.
Weird.
When I had GIAC X, my requested boost was consistently .3 bar below actual. The actual boost was at the correct level (18 psi taper to 11ish). This is with a new N75. I always thought it was weird, and I didn't get throttle cut. I then ran APR software for a while, and requested and actual were spot on, and the levels were the same as the actual I got with the GIAC X.
Weird.
#7
![Default](https://www.audiworld.com/forums/images/icons/icon1.gif)
6200 RPM. The software is supposed to make ~20 PSI throughout the RPM range from what I've been told by everyone including Todd@AWE.
Trending Topics
#8
![Default](https://www.audiworld.com/forums/images/icons/icon1.gif)
The ECU doesn't get feedback from the N75 other than resistance values to determine if its functioning/plugged in.
-Dave Pramanik
-Dave Pramanik