1.1.81 boost control

[AVP]

After a few tests and after Gintis advice, here is what i have now:

PID:0/0/0 Anytrim: OFF

Boost DC: 77% from 3000rpm---> gives 290kpa @ around 4400-4700rpm and holds. on 3d gear, on 4th it starts to become a bit higher on higher revs.
KPA target: at the time, set to 290kpa from 3000rpm onwards

Now my problem is the fact that the turbo can give me 310kpa easily on 3d gear from 4000rpm. So basically from 1.1.27 to 1.1.81 firmware i got more lag!

2 choices:

1) try using 85%DC from 2500-3500rpm then drop it to 77% to avoid spikes and see if i am getting rid of the lag?

2) Start tuning the PID--> I presume the P would allow for the solenoid to pick up signal to get to the target faster.Then the I will try and accelerate the rate of correction towards the error from the target, and finally the D will try and avoid the overshoot.

If that is the case, i usually use a large value on P and if it oscillates, i half it. Once its ok, i introduce the I with a small value, and if not ok, then bring in some D which usually is higher than the I.

Can i ask what is the most common PID settings that others have been using that seems to work? Esp if it is an audi!

thanks

vasilis

[AVP]

Here are some more results.

1) tried elevating the refDC higher, and it didnt work.

2) Introduced PID with various settings and settled for: 60/8/28. This tends to prevent overshoot and monitor boost as best as possible.

HOWEVER: on megatune, i was seeing boost much sooner still! and once i started increasing the I from PID, it started getting faster, but overshot! From 12 going to 14 on I, it wasnt working. Tried increasing D to compensate, nothing happened.

here are 2 photos from megatune and vemstune where you can spot the difference. Although in both occasions you see DC starting from 100 then tailing off, in megatune it comes up much faster, whereas in vemstune it doesnt require more than 78DC to keep 300+kpa after 5000rpm. which is ok, but the problem is the spool here.

can anytrim help on this matter? on megatune i was using boost offset of 8 in order to get my kpa target.

3d gear in both instances

VEMSTUNE


MEGATUNE

[MWfire]

something is diffrent now(mat is 5C higher).
Try to change inj angel, to 260-300deg.

[AVP]

how will that affect anything?

im a bit worried changing the injector angle. I have it from Marc Swanson as 430 on low revs and around 500 on the rest

can you explain a bit what it does and how it can help?

[AVP]

by the way, on megatune, MAT never affected the spool, only the target boost. It was always boosting less on hot weather.

[AVP]

after a few more tries, it appears that with elevating the P and keeping I and D stable at 7-8 and 28 respectivelly, the boost seems to be coming up better.

i would still want to know more about the injector angle though.

[GintsK]

So boost comes later? There is not so much what we can do to make boost comes earlier or later. Mainly it is upon to hardware.
You can prove it this way: 1) set overboost protection close to max acceptable value 2) disconnect all hoses (hose coming from N75) from W-gate. and 3) try to log 5th gear WOT until boost hits limiter. You will get maximal spool-up what is possible with your hardware with no influence form electronics.

430...530deg inj angle means injecting on closed valve before it opens. It is how mainly OE does. It's OK.

Gints

[AVP]

Gintis,

what you are saying is not possible. The only thing i changed to the car this week was the ECU from megatune to vemstune. So no hardware change. It is not possible to have lost because of it 300rpm spool!!!!

[GintsK]

So you got something impossible!  And now you have to sort out why.

BTW it is possible to get sooner boost build with retarded ignition. But it doesn't automatically mean better performance.

what part is worse: build-up part or area where N75 starts to reduce something?

[AVP]

i think it is simply PID control / boost control in general of vemstune. It just needs different control.

on megatune i was able to have PID: 240/5/52 and offset of 8 and got the above results. A rapid increase of boost and no issues.

With this one i can keep easier boost towards the end of the rpm, but i cannot get it to rise faster. I have tried increasing the P gradually with some good results, but anywhere near my old PID setting and the boost oscillates

[AVP]

the last setting on PID that worked yesterday was: 90/6/28. Did not spike and seemed to come up faster. I will try and make a log of it today, if vemstune does not get stuck!

[Jamo]

I'm watching this with interest since we have the same solenoid, I haven't played much with boost as I haven't got the roads locally to do boost runs.

I did a test on the weekend and my boost spiked to 2.2 bar over from 1.7 bar.

As I didn't use boost in 1.1.27 wasn't aware there was a lag difference.

What are you doing to make the logs? accelerating in 3rd gear? so I can log and recreate

[rob@vems.co.uk]

Where in the UK are you Jamo?

[Jamo]

I'm in Birmingham Rob

[billman]

I would prefer 4. gear logs (if it is possible of course) since there is more load and you likely have more spikes there.