Tuning AVCS without a dyno (AVCS for Gruppe-S header post 12 and 24)

[shr133]

Originally Posted by Tor

I still didn't mess up my AVCS, so am thinking about making this my next project.

In order to simplify it and reduce the number of flashes I so far came up with this idea. This is different intake valve settings that I plan to use (excuse my poor excel skills):



I would modify my current table first and flash that as a baseline, and make 1 tune with -4 deg and 2 tunes with +4 and +8 more advance. (The dip at 4200 in 2 of the variations is to see if I can get rid of a, in all likelihood fake, lean hump in my AFR curve).

I assume that following the original curve is not all that bad (OTS OFT AVCS) and that I, in any case, would cover most settings the would be realistic to potentially offer gains?

E.g I suppose it would hardly be realistic to expect +25 advance at 7400 to be reasonable, or +20 at 4800? So by staying around the original curve, I suppose I should have the best chances of actually finding any improvement?


Next, I would drive off to a flat road and do 4 pulls on each tune. I'm not entirely sure how to see which version is better. Virtual dyno is out of the question, due to the inaccuracy, unless it would surprise me with huge gains.

Here an example of 4 pulls done on the flattest road I have available, the fluctuations are too big (also you can see my lean hump in the AFR and that I tried to make VD show load in the boost graph without much success):


Instead, I was considering if mass airflow or load (or calculated volumetric efficiency) would be a good indicator of what makes more power? I would suppose if the engine is pumping more air that it would mean that it's making more power?

Here the loads of the same 4 pulls overlaid in Datazap (the blue one is slightly ahead in rpm). Of course, it wouldn't be necessary to overlay it like this, it just to visualize that they are indeed fairly similar compared to what VD outputs:


https://datazap.me/u/tor/test-2?log=...-4-21-22-23-24

What do you think about my idea? Any ideas or input appreciated. Or any fallacies in my reasoning or proposed method?

Thanks!

I would tune zone by zone.... so first zone is cruise and light acceleration.
Make an assumption and try it, keep making changes till you're happy. Go to the next zone medium acceleration, than full acceleration.

At low rpm less timing, max out in the mid range and less on the top end..
Back the exhaust timing down and flatten the map... Stock exhaust you can open the cams up faster. Good exhaust progressively open the cams.

The easiest way to measure gains is using dyno apps and timed acceleration runs from 30-60 in 2nd gear.

[shr133]

Dyno chart from perfexpert app.

[Compelica]

It's my turn now to screw up my AVCS. I know, the last update was 3 years ago but there's a wealth of information here which I would like to ride on

My tune is currently based on Wayno's and I'm looking to see what I can do to the AVCS to make things better. I did four runs each with the intake AVCS offset by -4, +4 and +8. Figured the tune would be already be pretty close to being optimized which shouldn't be far off.

So after a total of 16 pulls (got a flashlight shone on my face by a cop while flashing a tune but he was cool) these are my results:

Stock intake
Gutted 2013 OEM header
Stock exhaust, apart from Fujitsubo catback
Zeroed out KCA to reduce ignition timing



Between the 2800 and 5200 rpm range there are 3 peaks (!) which Shiv caters for two of them whereas Wayno consolidates them as a single peak.

OFT


Wayno


Now there's the issue which @Tor had also experienced, where the VVT was unable to catch up to the targeted value... while it does make sense that the values could be averaged out, but mine is showing really substantial dips. 36 to 48 to 36 back again as shown by the VVT tool from 3600 rpm to 4000rpm - is there something I'm missing? Should I cater for these peaks and valleys for the tune?

[tomm.brz]

first you always want those 40 in INTAKE to be 39
almost any of our cars can't reach 40 and this can trigger the vvt closed loop badly, like shutting it down for a second while in 6th gear in those engine load zones

then, vvt is imprecise and it tries its best to follow the target, but you can see by yourself that specially the exhaust cam, they tend to drift a bit specially on large swings

it s a compromise, if you get a strange slope with the vvt cams in your logs, try to adjust them in a slighty different way that won t cause a strange output

it wont go from 48 to 36 to 48 in so few rpms. it will just swing strangely trying to follow it

[Compelica]

Originally Posted by tomm.brz

first you always want those 40 in INTAKE to be 39
almost any of our cars can't reach 40 and this can trigger the vvt closed loop badly, like shutting it down for a second while in 6th gear in those engine load zones

then, vvt is imprecise and it tries its best to follow the target, but you can see by yourself that specially the exhaust cam, they tend to drift a bit specially on large swings

it s a compromise, if you get a strange slope with the vvt cams in your logs, try to adjust them in a slighty different way that won t cause a strange output

it wont go from 48 to 36 to 48 in so few rpms. it will just swing strangely trying to follow it

Thanks, that was my guess in the first place, the system wouldn't be able to track so quickly... but that is if you're sweeping RPMs. Given if you're cruising at low RPMs (where you stay at an RPM longer) there could be an advantage, but then again we're tuning for WOT here.

On the VVT shutoff, unfortunately I didn't do any 6th gear runs but most of the intake values are about 39 in the 40 range - no shutoffs though.

[tomm.brz]

as you said, that is for WOT, and that swing that you have in your calculated WOT best vvt has no sense to be honest
and in part throttle, the engine load varies so much that the ecu is going to pickup so many different cells of your vvt tables, that the output result will be anyway a "corrected" smoothed average of what it encounters. Don t use that tool for part throttling tuning

also why vvt#1 and #vvt2 has same value? one should be intake , one exhaust
I think something wrong or not attendible in your datalogs


Stock tune reach maximum 37 in intake advace, most cars wont reach 39, quite a few wont even keep 38 stable
I faced this with many people I tuned, if your car takes 40 of intake good, good for you and your car
but keeping it max 39 , like your vvt system reaches, will help the vvt closed loop working better, it 's pretty slow to be a closed loop, then do what you please!

[Compelica]

Originally Posted by tomm.brz

as you said, that is for WOT, and that swing that you have in your calculated WOT best vvt has no sense to be honest
and in part throttle, the engine load varies so much that the ecu is going to pickup so many different cells of your vvt tables, that the output result will be anyway a "corrected" smoothed average of what it encounters. Don t use that tool for part throttling tuning

also why vvt#1 and #vvt2 has same value? one should be intake , one exhaust
I think something wrong or not attendible in your datalogs


Stock tune reach maximum 37 in intake advace, most cars wont reach 39, quite a few wont even keep 38 stable
I faced this with many people I tuned, if your car takes 40 of intake good, good for you and your car
but keeping it max 39 , like your vvt system reaches, will help the vvt closed loop working better, it 's pretty slow to be a closed loop, then do what you please!

For #VVT2 I placed the same values as I was only changing intake, it's optional anyway.

What do you mean when it's 'slow' in closed loop I had always thought AVCS works the same in either open/closed loop conditions.

[tomm.brz]

i mean that the vvt system has a closed loop on its own, to try following the target.. I wasnt talking about the fueling

with slow , i just mean slow..
i mean look at sharp variations in the logs sometimes and then look the target, you have to keep this in mind while trying different cam tables

[Compelica]

Originally Posted by tomm.brz

i mean that the vvt system has a closed loop on its own, to try following the target.. I wasnt talking about the fueling

with slow , i just mean slow..
i mean look at sharp variations in the logs sometimes and then look the target, you have to keep this in mind while trying different cam tables

Gotcha. I saw your other thread where you were having said issues in 6th gear and you reduced the target values. Will try to test out that case as well when I have the chance.

Meanwhile, here's my intake table for now... have only changed 0.95 onwards and blended in 0.9. Will monitor the stability part in a couple of days. I know it's probably going to cause a lot of swinging and other issues - but nothing ventured nothing gained

[tomm.brz]

again, why put 43 if physical limit is 40, and your real limit is 39 ?
why stressing the ecu in trying to advance more and keep accumulating closed loop errors that will mess again with the vvt when the target changes and the actuator is slow to react, and the ecu pushes against it ?
you can create even more inconsistency

tried my best to help


i 'll try to show you an example from some logs i have, what happens when you put unrealistic/difficult to actuate values on vvt
give me some moments

[Compelica]

Originally Posted by tomm.brz

again, why put 43 if physical limit is 40, and your real limit is 39 ?
why stressing the ecu in trying to advance more and keep accumulating closed loop errors that will mess again with the vvt when the target changes and the actuator is slow to react, and the ecu pushes against it ?
you can create even more inconsistency

tried my best to help


i 'll try to show you an example from some logs i have, what happens when you put unrealistic/difficult to actuate values on vvt
give me some moments

I appreciate the advice @tomm.brz - not that I'm going against though I want to see these issues firsthand and get some more solid logs from it. It's not going to be anywhere final for this but I intend to experiment, it's all part of the learning process

43 is set because from the logs it can occasionally hold 40-42 although not as reliable as 38-39 most of the time.

I'd love to see those logs - I won't mind waiting

[Compelica]

Update - so after doing more analysis on the logs the >40 values only happens when it's ramping up - it will not hold on for long and the values drop to 39-40 later.

I'm mentioning the obvious here - it's as if the actuator 'overshoots' before settling on nominal values. And funnily enough it's not seen as an abnormality or an error by the ECU. Maybe actual hardcoded values in the assembly logic or something...

edit: Was mentioned before intakes have a range between -10 to 40. For mechanical hardware I suppose working it at its extreme ranges has its own issues.

[tomm.brz]

it just a little imprecise by design to me, it s commanded by oil pressure
funny is some cars act differently with the same setup same cam timings, maybe different oil give other results
That overshoot was what I want to show you with my logs, tomorrow when i ll have more time

[pro_turbo]

Give me both table intake and exhaust and i will test on my dyno