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Why does spark exceed spark table value (sometimes) on decel?
Posted: 2022 Aug 24, 17:11
by canuck1
The highest value anywhere in my FN2200 spark table is 43, but for some reason, after moderate accel to 4000 rpm, followed by a closed throttle decel I have logged as high as 49 dbTDC, generally about 2 secs after releasing the go pedal.
Just wondering why this happens?
Sean
Re: Why does spark exceed spark table value (sometimes) on decel?
Posted: 2022 Aug 24, 17:35
by canuck1
OK, looks like FN389 Dashpot CT spark multiplier is the culprit! the actual dbTDC value made me nervous but checking it against FN389 x SAFTOT, I can see it's adding timing to try and more quickly stabilize idle speed from closed throttle transition.
Sean
Re: Why does spark exceed spark table value (sometimes) on decel?
Posted: 2022 Aug 24, 18:14
by decipha
yep