Megasquirt Closed-loop boost control questions
01-22-10, 11:26 PM
#1
Sequentially broken
Thread Starter
Closed-loop boost control questions
I'm finishing up trying to theorycraft converting to use the built in boost controller operating in closed loop and I've got a few questions/things I'm not too sure about. I know Aaron mentioned he was using the controller, but I'm not sure if that was closed or not. In any event, I'm using a MS-II w/ 2.1.0.
Closed/Open duty cycle.
#1) I'm guessing these are the duty cycles where the solenoid is either fully closed or fully open. Does that mean the solenoid will constantly be powered, even if it's not in a bin where it needs to be controlled? I'm unsure of the purpose of these, except maybe to provide more accuracy of the specific range the solenoid operates within.
#2) There's not much information on gain settings, are there any recommended starting points? I've seen the 50/20/10 (Prop/Int/Diff), and that's about all I've found. I know ideally I should adjust/tune these to avoid 'spiking' or oscillation.
Boost Target table.
#3) Ideally I'd like to be able to keep my solenoid off (meaning not energized at all) at idle until throttle/RPM pick up to a reasonable rate. Can I enter in 0 for the low RPM/TPS bins to keep the solenoid from functioning? I'm a bit fuzzy on if it'd leave the solenoid powered at the % specified above, or if it'd just simply turn it off because a higher value for that bin is already acheived, so there's no need to power the solenoid.
#4) Is there any need to 'ramp' up to my target boost (say 12psi) as load/rpm increase? I'd imagine doing so would help to prevent boot spikes, but it also could potetially hurt spool. I'm trying to decide how best to lay out the bins. I've talked to one person who just told me to throw my target boost in all of the bins over 50% for any RPM range, but I worry that keeping the wastegate fully closed all the way to peak boost might result in spiking. Anybody have feedback on a good curve/method to start with? Right now I've got most of the moderate bins around 8psi leading up to 12 for most above 75%.
Closed/Open duty cycle.
#1) I'm guessing these are the duty cycles where the solenoid is either fully closed or fully open. Does that mean the solenoid will constantly be powered, even if it's not in a bin where it needs to be controlled? I'm unsure of the purpose of these, except maybe to provide more accuracy of the specific range the solenoid operates within.
#2) There's not much information on gain settings, are there any recommended starting points? I've seen the 50/20/10 (Prop/Int/Diff), and that's about all I've found. I know ideally I should adjust/tune these to avoid 'spiking' or oscillation.
Boost Target table.
#3) Ideally I'd like to be able to keep my solenoid off (meaning not energized at all) at idle until throttle/RPM pick up to a reasonable rate. Can I enter in 0 for the low RPM/TPS bins to keep the solenoid from functioning? I'm a bit fuzzy on if it'd leave the solenoid powered at the % specified above, or if it'd just simply turn it off because a higher value for that bin is already acheived, so there's no need to power the solenoid.
#4) Is there any need to 'ramp' up to my target boost (say 12psi) as load/rpm increase? I'd imagine doing so would help to prevent boot spikes, but it also could potetially hurt spool. I'm trying to decide how best to lay out the bins. I've talked to one person who just told me to throw my target boost in all of the bins over 50% for any RPM range, but I worry that keeping the wastegate fully closed all the way to peak boost might result in spiking. Anybody have feedback on a good curve/method to start with? Right now I've got most of the moderate bins around 8psi leading up to 12 for most above 75%.
