Tuning boost control on the MS3x
 

I've got the DIY solenoid. I'm trying to tune open loop to a good ratio before I tune closed loop, but it seems like from day to day the thing just overshoots the targets I set on the previous day. And not by a small amount. IE, one day it will hold 10psi to redline the next day it will overboost to the fuel cutoff (around 15psi) by 4000rpm.

I was under the impression that conditions could make open loop vary, but I didn't think it was that much.

Or am I doing it wrong? I'm using slow and 39hz freq range with control interval at 20ms. These were all the defaults I think.

I'm wondering if this is just the vagaries of open loop tuning biting me in the ass. Not sure yet, but will test today by varying parameters. I was just so surprised at how much variance there was from one day to the next that I didn't consider that small parameter changes make a large difference in open loop tuning and so weather changes might affect it as well.

that's why we dont use open loop...

I wasn't really planning to use it, but everyone says you should dial in open loop to some degree before going to closed loop, that's really all I was trying to do. I guess I just didn't realize how oddly variable it could be.

so long as it's close to your target and stable throughout the revs, id turn on CL now.

Okay, so you're right. The open loop mode is just super sensitive to changes. I got in the car today, same overboosting. I dropped the values in my table down by 5 points across the top end, holds boost fine. I guess it just gets to a certain point and once it is over that threshold it's just sky is the limit.

I'll start doing CL tuning now as this open loop stuff is nutso.

Also the clutch slips over 10psi. Oh well, new one on the bench.

So, does it matter if I have lower values in the boost table being lower boost and higher values being higher boost?

On the Boost Control manual it seems to indicate that higher values should indicate higher duty for the solenoid and therefore lower boost.

Boost Control

Edit: Apparently it does? Since the thing indicates

Or does it just not give a crap what is in the open loop table? I'm thinking that's what it is, once you go CL it doesn't give a crap.