Another boost controller help needed

[danycheung]

hello experts,

i've been playing around with the vems boost control.

i'm currently running boost control just with Boost refDC values(PID=0), from 1st gear pull to 3rd and 4th gear, the boost holds pretty nice as i want, but when Im rolling on 3rd or 4th gear and WOT, It builds boost so high that hits the fuel cut limit. (dont have the speed sensor settings configured, no idea how)

i switched back to PID control(P=214,I=70,D=60 as default came with my vems) to use the Boost target, instead of Boost refDC only, hoping that it wont go higher than map target, but the accel reaction is slower than the other setting,.

now, i want to know which configuration should i use and recommend?
also, changing which PID number would make the boost quicker?

thanks
dany cheung
urs6 + gt3076r + 440cc + vems

[gunni]

Post a log and your config and somebody should be able to shoot you some numbers.

I may be that you need to change the amount the PID control can actually lower or raise the DCref.

[danycheung]

ok, later i will log some runs with details.

thanks

[danycheung]

there ya go with my vemslog run i did after some runs on highway.

1st, 2nd, 3rd, and little of 4th gear.

http://rapidshare.com/files/413640803/v3.3_n002902-2010.08.18-03.11.19.vemslog

[andreNL]

Hi i'm busy understanding the controller.

PID is a verry accurate and sophisticated way of controlling the boost bleeder valve.
P proportional
I integral
D derivative
and i Integral windup

P controls the diffrence between set value (boost set point) and actual measured value.
it controls the the speed of change in diffrences between those values.
A high setting makes boost raise faster but overshoots the setpoint faster and higher (fuelcut boost creep ect).

Then the D comes in and pusshes the actual value back to setpoint value,

Then the I comes and fine tuning the last part of the movement diffrence between setpoint and measured value and keeping it steady around setpoint.

The i turns off the P and D when diffrences between setpoint and measerd value are out of range to much.

Search wikepedia for more theory about the PID controller.


Try to set I and D to zero,
set boost target low for testing put P value at zero and 255 see what happens.
Take a value with an acepptable value of overshoot.
dial in the I value and then the D value.

Also see what happens if you drive with low boost en go to WOT whith a i setting.

Then turn the boosttarget back to the desired value.
cheers...