Dashpot decay factor? Can't find info the manual
#1
Dashpot decay factor? Can't find info the manual
I've got a Reverant built MS2 running great on my MSM. I had one tiny issue with a idle droop when coming to stop signs.
I did 2 things to try to solve the issue, increased Min Duty for PID % from 18 to 20, and added 5% to Dashpot adder %.
Now when coming to a stop, the car hangs the idle at around 1050. It takes probably 5-6 seconds to settle from there to my target of 850. This is significantly less annoying than having it droop to 500, scaring the crap out of me like its going to stall (although it never does), and then coming back up to the target of 850.
I'd just stop here if I could leave well enough alone, but I can't. I can't figure out what "Dashpot decay factor" is. I can't locate a reference to it in any manual and i'm not sure how to begin adjusting it. I can find "Dashpot decay rate", but I don't know if that's the same thing or not. I suspect it could improve/reduce the amount of time that the idle now hangs when coming to a stop. Anyone have any info on this, what it does, and what a good starting point would be?
THANKS!
I did 2 things to try to solve the issue, increased Min Duty for PID % from 18 to 20, and added 5% to Dashpot adder %.
Now when coming to a stop, the car hangs the idle at around 1050. It takes probably 5-6 seconds to settle from there to my target of 850. This is significantly less annoying than having it droop to 500, scaring the crap out of me like its going to stall (although it never does), and then coming back up to the target of 850.
I'd just stop here if I could leave well enough alone, but I can't. I can't figure out what "Dashpot decay factor" is. I can't locate a reference to it in any manual and i'm not sure how to begin adjusting it. I can find "Dashpot decay rate", but I don't know if that's the same thing or not. I suspect it could improve/reduce the amount of time that the idle now hangs when coming to a stop. Anyone have any info on this, what it does, and what a good starting point would be?
THANKS!
#2
Dashpot Adder takes the last known value for your PWM output and adds that % to it when getting back into CL idle. So say you had been idling at 32% PWM output, the next time it comes in it will automatically go to 37%. This is why your idle is high.
Edit: You already know this. Nevermind. I don't know how to work the decay. Sorry!
Edit: You already know this. Nevermind. I don't know how to work the decay. Sorry!
#4
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5% is pretty high, I use like 2%. i bet you're going lean as you come down to idle and why you need so much.
the decay is how long it stays at your dashpot number before it comes down to the last value; I use 0 for that.
Also make sure your CL delay isn't very long I use 2.
the decay is how long it stays at your dashpot number before it comes down to the last value; I use 0 for that.
Also make sure your CL delay isn't very long I use 2.
#5
5% was just want I plugged in to start with, I may have to go down from there. I'll also check my AFRs more closely returning to idle and adjust if needed. I'll need to turn my overrun off to see whats going on there.
My CL delay is also 2. I was noticing the dip just before CL kicked in. It didn't last long as CL fixed it after 2 seconds.
I was worried that 0 for the decay factor would do something odd like never decay. I'll keep messing with it, I think i'm on the right track. Thanks for confirming.
My CL delay is also 2. I was noticing the dip just before CL kicked in. It didn't last long as CL fixed it after 2 seconds.
I was worried that 0 for the decay factor would do something odd like never decay. I'll keep messing with it, I think i'm on the right track. Thanks for confirming.
#6
For anyone else looking, I did end up finding the documentation that explains this feature and more. The PDF is in the first post of this thread: http://www.msextra.com/forums/viewto...p?f=91&t=43793
#7
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5% was just want I plugged in to start with, I may have to go down from there. I'll also check my AFRs more closely returning to idle and adjust if needed. I'll need to turn my overrun off to see whats going on there.
My CL delay is also 2. I was noticing the dip just before CL kicked in. It didn't last long as CL fixed it after 2 seconds.
My CL delay is also 2. I was noticing the dip just before CL kicked in. It didn't last long as CL fixed it after 2 seconds.
AFRs and timing really effect idle speed, so make sure that's kosher so things are stable before you go into CL idle.
Last edited by Braineack; 06-25-2012 at 10:34 AM.
#11
I've solved most of my issue by adjusting overrun to return fuel earlier (Thanks brain). This allowed me to bring my Dashpot down from the 5% I had originally to 2%. Also changed decay factor to 1. Its now perfect/stock-like.
Now I just need to work on getting my throttle blips while rev-matching as crisp as I'd like. I cleaned up the bottom of my VE table and that helped a lot, but its still not perfect. I'm guessing I need to mess with AE next?
Now I just need to work on getting my throttle blips while rev-matching as crisp as I'd like. I cleaned up the bottom of my VE table and that helped a lot, but its still not perfect. I'm guessing I need to mess with AE next?
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