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Old 11-07-2012, 05:30 AM   #1
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Default New boost control strategy in MS3 - with initial duty table, how to set...

Hi guys,

I don't know if you have already seen, this - there is a new boost control strategy in the MS3 pre 1.2 alpha 4 with an inital boost duty value table...

Megasquirt MSEXTRA / MS3EFI • MS3 pre-1.2 alpha4 released (View topic)

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How does this initial value work? (If it's possible to describe this in easy words)


It looks up your boost target, then if this new feature is enabled, it looks up the duty you want associated with that target and sets that duty. Once you are close to that target, it enables PID with the duty starting where you set.
I really thing this sounds nice and might even improve spool a bit...
So I am left with the question about how to set this inital duty table..

I had a look at some logs and tried to separte some of the dutys at specific rpm/boost(map) combinations... But this only works for a very limited part of the initial duty map (~around my main target boost - I highlighted this red in the table). I tried to inter- an extrapolate the rest of the table... Here is what I got, does this table make sense?



I really would be grateful if you could help me out with this... (It's very theoretic right now for me, as my car is in winters sleep until 1st of April 2013

I also wasn't quite sure about the scaling of that table, does my scaling for a target boost of 170kPa look right?

P.S.: Be careful with this alpha 4 there seem to be bugs in CL idle, a new alpha 5 will eventually come out today...
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Last edited by Zaphod; 11-08-2012 at 03:32 AM.
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Old 11-07-2012, 11:03 AM   #2
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turn boost to open loop.

tune the open loop duties table so you maintain your boost target.

copy those values to your initial duties table.

????

Win at life.



(it works the same way in which your intial idle duties table work. which you are using, right?)
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Old 11-07-2012, 02:38 PM   #3
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Wrong. No easy win to be had here...

The Open loop table is y-axis TPS X-axis RPM and Duty Cycle

The inital value table is y-axis Boost target X-axis RPM and Duty Cycle.

I can onlyfill a very small part of the inital value map out of my open loop dutys.
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Old 11-07-2012, 02:49 PM   #4
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oic.

I'd still just determine what duty = what boost level and work from there.
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Old 11-08-2012, 03:42 AM   #5
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What about the 2000&3000 rpm columns? I have no real values for them (as I reach my boost target at ~ 3300rpm)

The values in my datalogs are very small for this columns because my EBC starts working at 120kPa and reaches target very fast so I suppose these values are not a correct starting point...

Should I make them higher as the 4000rpm column? Would this help spool?

Or would I risk overshoot because the PID starts with too high dutys...?

(I will be asking these question also on Msextra.com - maybe the devs can also help me a bit with this...)

Greets
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Old 11-08-2012, 09:35 AM   #6
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I would put in 100% so you keep the valve closed. I would put in real duty targets maybe 300-400RPM below your boost threshold.
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