MoTeC Global Forum

Hi,
Having some trouble setting a good boost control using a 3 Port MAC boost solenoid and JRR Firmware..
Under boost control menu, I set all PID's to 0, and manually tuned/setup the Boost Target and Feedforward Tables, when I go above 1.4 bar at around 5500rpm and 6200rpm the boost fluctuates 0.2bar above and below target..
Set the frequency from 10Hz to 40Hz and nothing changed.
If I replace the MAC EBS(I tried 2 MAC's) with a manual boost control valve, boost is steady across the rpm range.
Shouldn't boost be steady if all PID's are set to 0 or is it mandatory to also tune the PID tables to get a stable boost line ?

Thanks
Kam

Hi,

I normally run a MAC valve at 30hz.

The PID having values greater than 0 turns on the closed loop control, if they are all set to 0 then it will be running in Open Loop which is dictated by the Feed Forward table.

It may be a mechanical or gas flow issue that you are seeing, where the system is not able to flow enough mass through it leading to surging, or your exhaust back pressure is too great.

Stephen Dean wrote:Hi,

I normally run a MAC valve at 30hz.

The PID having values greater than 0 turns on the closed loop control, if they are all set to 0 then it will be running in Open Loop which is dictated by the Feed Forward table.

It may be a mechanical or gas flow issue that you are seeing, where the system is not able to flow enough mass through it leading to surging, or your exhaust back pressure is too great.

Thanks Stephen,
But why is boost so stable with the manual boost controller valve, like Hallman or HBC...
This I'm not understanding...
If I "tune" the PID's, do you think I can solve that ? Like putting some"D" value where it flutters ?

Thanks
Kam

Hi Kam,

Are you running the same boost with the MBC? Have any other changes been made to the system other than adding the MAC valve? It may be that because the MBC is a constant bleed, and the Mac valve is pulsing, that there is a harmonic building through that pressure/engine speed range.

Do you have any logging of this occuring?

Stephen Dean wrote:Hi Kam,

Are you running the same boost with the MBC? Have any other changes been made to the system other than adding the MAC valve? It may be that because the MBC is a constant bleed, and the Mac valve is pulsing, that there is a harmonic building through that pressure/engine speed range.

Do you have any logging of this occuring?

Hi,
Yep same boost, 1.5 Bar
No other changes at all, just swapping MBC and EBS
Now it's raining and the roads are wet.. Will attach some logs later
"that there is a harmonic building through that pressure/engine speed range" How to get rid of that / Fix it ?

Is there a restrictor pill in any of the lines?

Stephen Dean wrote:Is there a restrictor pill in any of the lines?

Not sure, but I think Not