Thread: VE%
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Old 10-15-2011, 12:19 AM   #5 (permalink)
mwebb
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no nickname , it's just a car - '04 volkswagen golf tdi
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can not Measure VE


note on the graph , at high flow calculated and actual air flow are very close , differences measured on the grid on the right , but at low flow , calculated and actual are much farther apart - differences can be huge , depending on the system -
you can measure change in efficiency by measuring calculated load at WOT under consistent condition s , a higher value of calculated load at WOT means you have improved your systems ability to flow
air

the system above is in very poor condition as on that system , calculated load should peak close to 150% at WOT as it is a turbocharged AWM engine
during this test , fuel trim should be within +/- 5% from zero , the system above is in heavy add indicating an under reporting MAF sensor OR restricted fuel to or through the injectors
, on a normally aspirated engine calculated load or engine load of 100% is the goal but real world values will be closer to 90%

http://farm6.static.flickr.com/5058/...6c2b9636_b.jpg
an NA engine with an under reporting MAF sensor , fuel trim is adding over 15% mac engine load is 80% , defective new MAF sensor

an increase in calculated load is always an improvement in flow IF and only IF test conditions are IDENTICAL.
so
if you wish to test your system
use calculated load or engine load at WOT ,
never use Absolute load , it will always be 100%

you can not measure VE accurately at any throttle position besides WOT so
i would focus on something else

when doing these "tests" , use a copilot to monitor scan data - so you remain alive to post your "test" results
------------------------
using VE graphed at WOT with good and a bad MAF sensor , same car , same test conditions
http://farm4.static.flickr.com/3469/...d0ce6789_b.jpg

Last edited by mwebb; 10-15-2011 at 12:31 AM.. Reason: proof read
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