How would a bad N75 valve affect requested boost?
10-30-2006, 10:45 AM
#1
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How would a bad N75 valve affect requested boost?
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.
10-30-2006, 11:11 AM
#5
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Dave, recall that (at least sometimes) Requested boost is not affected in limp mode
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
10-30-2006, 11:14 AM
#6
Unfortunately, I can't see images from imageshack at work...
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.
10-30-2006, 11:17 AM
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Interesting. The above graph shows requested boost curve of ~16 PSI midrange increasing to ~17.5 by
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.
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10-30-2006, 11:18 AM
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Yeah, I don't see how a faulty N75 would affect requested boost.
The ECU doesn't get feedback from the N75 other than resistance values to determine if its functioning/plugged in.
-Dave Pramanik
-Dave Pramanik