0% WGDC?

ferocity02 · 01-23-2015, 12:58 PM

I'm in the process of getting my N54 tuned via Cobb V3, and every now and then monitor the gauges while driving normally. The other day I noticed that the WGDC will drop to 0% after being on the highway for about 10 miles. It will stay at 0% unless I give it a moderate amount of load and then it will jump up to ~20% or so depending on the load.

If I give it just a blip of additional load, the WGDC will then fall back to 0% after letting off the gas. If I hold the additional load for a bit longer, say 5+ seconds, the WGDC will fall back to around 9-10% after letting off the gas instead of 0%. After another 30 seconds or so or normal light highway driving, it will fall back down to 0%.

Is this normal? Is it some sort of "eco" mode?

jwzimm · 01-23-2015, 01:52 PM

I am not an expert but it seems like the system is anticipating your need for boost and then, after a time, realizing you are at cruise and you do not need it. If the car kept the WG closed or partially closed during cruise you would see pretty bad gas mileage as the backpressure would make the engine have to work harder. At low loads the engine does not require boost so it is opening the WG to run the motor more like an NA engine.

ferocity02 · 01-23-2015, 02:05 PM

Quote:

Originally Posted by jwzimm

I am not an expert but it seems like the system is anticipating your need for boost and then, after a time, realizing you are at cruise and you do not need it. If the car kept the WG closed or partially closed during cruise you would see pretty bad gas mileage as the backpressure would make the engine have to work harder. At low loads the engine does not require boost so it is opening the WG to run the motor more like an NA engine.

That's what I was thinking. When not at 0% it will normally be at 8-10% during cruise and very light throttle. I assume 0% means they are fully open?

jwzimm · 01-23-2015, 02:28 PM

I think they have a spring closure on them as well which provides some backpressure to keep the turbo's spinning. This would produce a small amount of boost but not as much as with them being controlled closed.

I am basing this off my experience on the Subaru platform though so don't quote me. I believe this is basic turbo design methodology.

01-23-2015, 12:58 PM	#1
ferocity02 Colonel 564 Rep 2,085 Posts Drives: 2013 135is Join Date: May 2014 Location: USA iTrader: (8)	0% WGDC? I'm in the process of getting my N54 tuned via Cobb V3, and every now and then monitor the gauges while driving normally. The other day I noticed that the WGDC will drop to 0% after being on the highway for about 10 miles. It will stay at 0% unless I give it a moderate amount of load and then it will jump up to ~20% or so depending on the load. If I give it just a blip of additional load, the WGDC will then fall back to 0% after letting off the gas. If I hold the additional load for a bit longer, say 5+ seconds, the WGDC will fall back to around 9-10% after letting off the gas instead of 0%. After another 30 seconds or so or normal light highway driving, it will fall back down to 0%. Is this normal? Is it some sort of "eco" mode? __________________ 2013 135is DCT Carbon Black Metallic
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01-23-2015, 01:52 PM	#2
jwzimm Colonel 695 Rep 2,770 Posts Drives: '16 M3 Join Date: Jun 2011 Location: Renton, WA iTrader: (17)	I am not an expert but it seems like the system is anticipating your need for boost and then, after a time, realizing you are at cruise and you do not need it. If the car kept the WG closed or partially closed during cruise you would see pretty bad gas mileage as the backpressure would make the engine have to work harder. At low loads the engine does not require boost so it is opening the WG to run the motor more like an NA engine. __________________ 2008 Honda S2000 - Current 2016 F80 M3 - SOLD!! 2011 e92 X-Drive Coupe - SOLD!!
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01-23-2015, 02:28 PM	#4
jwzimm Colonel 695 Rep 2,770 Posts Drives: '16 M3 Join Date: Jun 2011 Location: Renton, WA iTrader: (17)	I think they have a spring closure on them as well which provides some backpressure to keep the turbo's spinning. This would produce a small amount of boost but not as much as with them being controlled closed. I am basing this off my experience on the Subaru platform though so don't quote me. I believe this is basic turbo design methodology. __________________ 2008 Honda S2000 - Current 2016 F80 M3 - SOLD!! 2011 e92 X-Drive Coupe - SOLD!!
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