Boost target table - how does yours look...? - Miata Turbo Forum - Turbo Kitten is watching you test compression.

Zaphod · **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

*Faeflora* · 06-11-2012, 02:26 AM

No see um pic.

Zaphod · 06-11-2012, 03:51 AM

Should be working now...

***Braineack*** · 06-11-2012, 08:50 AM

See if adding a little bit more D helps. What are you PID settings?

Zaphod · 06-11-2012, 09:23 AM

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...

***Braineack*** · 06-11-2012, 09:28 AM

really close to what i have, but i think Im using 100D. Might want to try it?

Zaphod · 06-11-2012, 09:46 AM

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 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...