The Dyno Dip
Jon Pennington
cowboydren at b15sentra.net
Wed Mar 24 17:36:09 CST 2004
Matt Davis said:
> http://www.b15sentra.net/mdavis/albums/hosts/DYNOSEAF.jpg
> Could that be what causes the engine to do that Dip at that rpm range?
Well, I don't see timing on *that* graph, but I wonder if you're looking
at effect, rather than cause. If it's as Mike said (uh, usually he's
right ;)), it's a resonant/harmonic thing, where the MAF sensor indicates
A# of air flowing, and the ECU sends F# of fuel to compensate. But
there's a tumbling thing going on somewhere between the MAF and the moment
the valve closes, and the engine doesn't actually *get* as much air as the
MAF indicated was available, which would explain the rich dip. I think it
would be cool to see an OBD-II-sourced line that draws the actual timing
curve through the band as well, just to be sure.
Other wierdass sidenote; why do all of the charts I see on roller SRs have
wildly lean fuel mixtures below 3500 RPM?
--
-=|JP|=- "Stays Fresh Longer!"
'01 B15 SE/PP | http://members.cardomain.com/cowboydren/ | <//><
'95 SL2 Auto | cowboydren @ b15sentra . net |
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