What happens when injectors pass 100%?
Oct 15, 2012 | 04:06 PM
#1
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Joined: Oct 2004
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From: Crystal Springs, MS
What happens when injectors pass 100%?
Looked at my log from friday night and saw 200% IDC 
AFR was creaping up to 12.3 (commanded 11.2)
i had replaced my DO7 for a DO14 meth nozzle, then later i added the D07 back for a total of a D07, DO10, and DO14 nozzles. 31gph methanol.
tuned it in and made a pass, top of first it ramps up to~10psi, then after the 1-2 shift it goes up to 15psi and holds it there.
AFR was creaping up to 12.3 (commanded 11.2)
i had replaced my DO7 for a DO14 meth nozzle, then later i added the D07 back for a total of a D07, DO10, and DO14 nozzles. 31gph methanol.
tuned it in and made a pass, top of first it ramps up to~10psi, then after the 1-2 shift it goes up to 15psi and holds it there.
Oct 15, 2012 | 04:16 PM
#2
Joined: Jan 2006
Posts: 16,282
Likes: 438
From: Huntsville, AL
Nothing...IDC is a measure of the ratio of time open over time possible. 100% means it is open the entire time possible, so a value greater than 100% is impossible and doesnt make sense (open longer than able to be open...).
It is also a calculated value based on the IFR table, commanded equivalence ratio, ve table (or maf) and rpm, which is why it will show over 100%. If yours says 200% then you need injectors twice as large...if you didnt have meth you would be waaaay lean.
Should also note, it doesnt matter what the AFR actually is because the stock ECM does not have closed loop control outside of stoich. So no matter if you are actually very rich or very lean, IDC will not change. Again, its calculated based on rpm, IFR table, VE table (or maf), and commanded equivalance ratio (1/lambda). If all of those parameters are correct (especially ve table, and IFR table), the IDC is very accurate.
It is also a calculated value based on the IFR table, commanded equivalence ratio, ve table (or maf) and rpm, which is why it will show over 100%. If yours says 200% then you need injectors twice as large...if you didnt have meth you would be waaaay lean.
Should also note, it doesnt matter what the AFR actually is because the stock ECM does not have closed loop control outside of stoich. So no matter if you are actually very rich or very lean, IDC will not change. Again, its calculated based on rpm, IFR table, VE table (or maf), and commanded equivalance ratio (1/lambda). If all of those parameters are correct (especially ve table, and IFR table), the IDC is very accurate.
Oct 15, 2012 | 04:22 PM
#4
Joined: Jan 2006
Posts: 16,282
Likes: 438
From: Huntsville, AL
The cutout on your wastegate or exhaust? That points to your exhaust being very restrictive.
Since your setup is different from most, I am betting that if you (in reference to the cutouts)...
Open downpipe, closed gate - very high boost (ie, poor boost control)
closed downpipe, open gate - very low boost (ie, great boost control)
closed downpipe, closed gate - medium boost (due to poor turbine expansion and choked gate)
open downpipe, and open gate - best setup (good turbine expansion and high gate authority)
Since your setup is different from most, I am betting that if you (in reference to the cutouts)...
Open downpipe, closed gate - very high boost (ie, poor boost control)
closed downpipe, open gate - very low boost (ie, great boost control)
closed downpipe, closed gate - medium boost (due to poor turbine expansion and choked gate)
open downpipe, and open gate - best setup (good turbine expansion and high gate authority)
