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Old 06-11-2012, 02:33 AM   #1
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Default Boost target table - how does yours look...?

Hi guys,

after I got my MS3(X) running nicely I took a ride yesterday and got the VE dialed in quite a bit.

As I cruised at the Autobahn I had one spot that I had a little problem...

Scenario is - light throttle cruise TP ~30%, speed is a t 180 kph (~ 111mph) and boost is around peak (170kPa). The boost control is working perfectly well when I give the throttle a nice stab, but at that low throttle the MAP is starting to oscillate...

See:


This is how my boost target table looks at the moment:


As you can see - at 30% TPS the boost is exactly between to different targets (I guess the MS interpolates them..?).
The oscillations can well be because of my rough VEtable - but could also be hunting between the two different boost targets. (?)

So I thought a bit about how a correct boost target map would look like...?!
How does yours look?

Thanks
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Boost target table - how does yours look...?-boost_at_low_tps.jpg   Boost target table - how does yours look...?-boost_target_sr.jpg  

Last edited by Zaphod; 06-11-2012 at 04:51 AM.
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Old 06-11-2012, 03:26 AM   #2
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No see um pic.
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Old 06-11-2012, 04:51 AM   #3
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Should be working now...
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Old 06-11-2012, 09:50 AM   #4
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See if adding a little bit more D helps. What are you PID settings?
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Old 06-11-2012, 10:23 AM   #5
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PID is at 22/22/70 now -
Control interval is at 10ms.

with higher TPS the boost control is near perfect.

Gets to target fast, holds target till redline, doesn't overshoot too much...
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Old 06-11-2012, 10:28 AM   #6
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really close to what i have, but i think Im using 100D. Might want to try it?
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Old 06-11-2012, 10:46 AM   #7
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I am going to try for sure - I am always a bit scared of this high D values, because I thought they would bring oscillations...

Ken seid in this thread (where some other member asked about bc tuning) at Msextra just some days ago:

Quote:
just keep adding P to counteract the initial overshoot as you add I. Once you get it working with minimal overshoot with just P and I, and you have it holding the target across the rev range, you can add some D (sparingly) to get rid of overshoot.
Maybe 100 is sparingly... it all depends on point of view...

Edit:
Quote:
Originally Posted by Braineack View Post
really close to what i have
I have noticed, that the PID values on all the Miata MS2/3 tunes I have seen tend to be very close...
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