Hustler's build thread 2.0, the natural aspiration connection
09-09-2012, 12:14 PM
#288
I have, its from pushing the timing to the limit. You need it on map cars for the same reason you need transient throttle enrichment. The real air load has increased before the measured air load has. And running the tune at the limit you will get it. Or if you're just an OEM who has the car tuned for gas mileage. Often you pass through the gas mileage cells at this time where you're running crap loads of timing. But I'll normally give up some power and fuel economy if the ecu doesnt have tip in knock retard.
Last edited by Leafy; 09-09-2012 at 12:37 PM.
Reply
-1
-1
09-13-2012, 09:36 AM
#295
Even with proper afr from transient fueling you can still get knock either from the map sensor not reading the actual load (same reason you need transient fueling) and passing through cells with way too much advance. Or even just from the nature of whats happening during those transient throttle events. If the OEM's do it and you hit this preventative knock retard on a stock car with a stock tune, don't you think it would be a nice thing to have?
Reply
0
0
09-13-2012, 10:00 AM
#297
Elite Member
iTrader: (9)
Join Date: Jun 2006
Location: Chesterfield, NJ
Posts: 6,891
Total Cats: 398
If the OEM's do it and you hit this preventative knock retard on a stock car with a stock tune, don't you think it would be a nice thing to have?
Reply
0
0
09-13-2012, 10:09 AM
#298
And yes acceleration enrichment based off of delta TPS is the right way to do any transient response tables because the tps reacts instantly to the drivers requested air flow.
Reply
0
0
09-13-2012, 10:32 AM
#299
Elite Member
iTrader: (9)
Join Date: Jun 2006
Location: Chesterfield, NJ
Posts: 6,891
Total Cats: 398
The majority of the issue with lean tip-in is due to the fact that a gaseous fuel/air mixture at xxx absolute pressure will separate into not a gaseous fuel/air mixture if that pressure changes rapidly and positively, the extent of which varies depending on a few variables. Going from a high vacuum to not so much vacuum in a relatively short time period causes some fuel to come out of suspension. Lean spike.
Same reason there is decel enrighment. Snap that throttle shut and the fuel puddled on various walls goes to vapor from the massive vacuum change. Rich spike.
Like we agree, TPS signal is a much more accurate signal, time wise, to tune a trim to account for this phenomenon.
Signal delay within MAP sensor based fuel/ignition maps surely would have an effect too, but not as great in my opinion.
I follow you. Valid point taken. I have not seen a deltaTPS/time ignition retard/advance feature in my limited experience with tuneable ECUs. I have also never looked at a megasquirt.
This makes me want to see how much more timing I am running at lots of vacuum compared to atmospheric pressure. I don't think there's much difference so this feature, if it did exist, might not matter much for my particular setup. And under boost, my MAP sensor signal responds quicker than the turbo.
Same reason there is decel enrighment. Snap that throttle shut and the fuel puddled on various walls goes to vapor from the massive vacuum change. Rich spike.
Like we agree, TPS signal is a much more accurate signal, time wise, to tune a trim to account for this phenomenon.
Signal delay within MAP sensor based fuel/ignition maps surely would have an effect too, but not as great in my opinion.
If you're determining air flow through math based off of a map sensor and have already agreed that a map sensor doesn't give accurate results during transients then how to you expect to be using good data to determine your spark advance?
This makes me want to see how much more timing I am running at lots of vacuum compared to atmospheric pressure. I don't think there's much difference so this feature, if it did exist, might not matter much for my particular setup. And under boost, my MAP sensor signal responds quicker than the turbo.
Reply
0
0
