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Power FC why the disconnect between base fuel and AFRs?

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Old 12-12-04, 05:54 PM
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why the disconnect between base fuel and AFRs?

i have to spike my base fuel Ms at N10 to maintain a smooth AFR between N9 and N11.

this only appears at P11 and into boost. might it have something to do w primary/secondary fuel injector transition?

for example:

at P12..... N9 is 13.537 ms N10 is 16 N11 is 13.388

my AFRs are 13 12.7 and 12.8 (my target is 12.83 at .1 bar of boost 1.1 bar)

i run 850 primary 1600 secondary. settings page is 64.5 for the primary. .04 and .14 for lag. primary secondary transition 40% secondary transition .996 ms


any help would be appreciated.

howard coleman
Old 12-13-04, 06:50 PM
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steve kan pointed me in the "injector overlap" direction as a solution. settings page 5. i will work it during the last few days on over the road logging... winter is starting to settle in around wisconsin.

i did an "injector overlap" search and found some very interesting posts as to the "why" of the lean spot around primary/secondary staging exactly at the transition from zero boost northward.

thanks steve.

howard coleman
Old 12-13-04, 10:04 PM
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A possible test to verify if this is a transition problem would be to change the pri/secondary transistion %. For example if you changed from 40% to say 70% this would shift your affected cells to higher p rows or higher n columns.
Old 12-13-04, 11:11 PM
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Howard: Sounds like your 1600cc inj's are coming in too slowly.....that lag time needs to be increased to somewhere between .20 and .30.
Sec transition should be moved back to 1.5mS 'til things get sorted.
And another finding of mine......whenever using big sec injectors I raise the prim/sec transition to ~50%, it seems to smooth out the transition.

1st try the lag time then move on to the transition %.....and let me know how it works out.
Are you using resistors on those 1600cc ???

Good Luck,
JD
Old 12-14-04, 06:38 AM
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thanks for the help JD. i will share my findings and, yes, i do have resistors on my 1600s.

howard coleman
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