General SAFC Throttle postion help!

[spitefire1]

on the safc you choices to set up your throttle percentages like hi and lo throttle. what is a good postion. like i have it know set on 30% lo 80 % hi is that good? can it be better? wb thanks brandon

 

[ilco187]

some use 30/70 but then it has to calculate in between them points, so i use 69/70 i guess from what i have read that is the best to set but

 

[spitefire1]

like i was doing some research and people say use lo 30% hi 50%. is that better/ how is lo 69% hi 70%. i rele wnna know what is the best for tunning to get the most out of an afc.

 

[ilco187]

you can set your throttle points to your driving, for example if at cruise you only press on the throttle 30% set the low for 30% when you a little more heavy on the pedal say like 80% set the hi at 80% its really based on how you use the throttle.

 

[jeffo]

The ECU switches from closedloop to openloop at about 40% throttle, or 4000 rpm, depending upon a few parameters. So, the way I prefer to setup an AFC is to think of the AFC LOW settings as closedloop, and the AFC HIGH settings as openloop. If you set it up for 30/50, just mirror whatever 1000-4000 rpm settings you come up with on the AFC LOW sliders over into the AFC HIGH, where they are probably never going to be used anyway. Same with the 4500+ AFC HIGH settings. After you have tuned your openloop/WOT AFR where you want it on the AFC HIGH settings, mirror those settings over into the AFC LOW sliders, where they are probably never going to be used either. That actually only leaves a very narrow rpm range where the closedloop and openloop operations could possibly overlap.
keydiver

 

[mikelv]

Whatever you set it at, the midpoint corrections will only will be average of your hi and lo setting throughout the range. SAFC is one dimensional and only reading one average.

For example, you use 30% 80% and you low settings are 20% and your high settings are 10% at each RPM level.

Your midpoint correction is going to be 15% across the board meaning the airflow signal is going to be 15% @ 31% throttle and 15% at 79% throttle, no matter what you do. In our example, at 80% throttle it'll switch over to 20% correction.

When I first started using the AFC I thought it was actually indexed. So if you had a 15% average (the 20% & 10% example) then it would gradually increase as you increased throttle. For example, 31% would be 15% correction (your base low setting) and 32% would be like 15.2% (just an example), and 33% would be slightly higher, until you were at the midpoint of your midpoint (being 50% in this case of 30-70) and at 50% throttle you would have a correction of 17.5%. But nope, it's 15% at every point in between. Bum deal if you ask me. The AFC should have a map that is indexed by throttle points at least. Therefore, you could dial in a map at every point you wanted in the RPM range.

This would allow you to dial in settings based on boost levels, ect...

If you had a more advanced system this correction factor would be direct and indexed by RPM, Throttle, and Correction. You could dial in whatever setting you wanted for 31%, 32%, 33% and so on. Complete engine control for every parameter.

So set up your AFC for what you want it to do. If you want a lean, gas saving setting for low cruise, and you drive around normally under a certain throttle position, set it for that. When you want a wide-open throttle setting, judge it accordingly.