So the notch from NWS cam switchover has been talked about in part in different threads on here, but I haven't necessarily seen explicit input on how people have been tweaking the maps to overcome the notch in load/boost/fueling that often occurs.  I haven't seen much about what people have actually found out about this, just some vague references that they were able to work it out.  Here's some of the input that I have seen so far:

S4 wiki (http://s4wiki.com/wiki/Tuning#Cam_changeover_effect_on_requested_boost) - maps relating to this are
    KFPBRK - Correction factor for combustion chamber pressure
    KFPBRKNWS - Correction factor for combustion chamber pressure when NWS active
    KFPRG - Internal exhaust partial pressure dependent on cam adjustment when sumode=0
    KFURL - Conversion constant for ps->rl dependent on cam adjustment when sumode=0

And I will add these two maps as relevant:
    KFNW - Characteristic map for variable camshaft spread
    KFNWWL- Timing for variable cam, warmup


Phila Dot says:



NotoriousVR says:


Here's his log with the notch gone in boost, and the notch in load calmed for the most part:



As for my input, I've played around just a little bit with it with a little success, but haven't had time to iron it out and I'm not sure the best way to go about it yet.  Some things to note on my setup: GT turbos, 2.8l heads & cams.  Here is the notch in my logs as I make some slight tweaks to the cam switchover maps (the 6 maps referenced above) between revisions:

File #1 - Stock settings on all cam switchover maps, you can see the notch is in load (rl_w), MAF, injector, and in my actual AFR between 3800-4100RPM it shoots sharply down rich (I've verified that this has nothing to do with any of the MAF/fueling maps and is almost surely from NWS):







File #2 - On the advice of Phila_dot, I tweaked KFPBRKNW a little; in the last two load columns of the 3800 RPM row (the 140% & 170% load columns, as that is what load I was above in 3rd gear WOT, per the previous logs) I raised the value from 1.075 to 1.11.  You can see it subdued the magnitude of the load notch for sure, but it looks like it introduced a requested boost notch from 3500-4000. The actual AFR notch is helped a little.







File #3 - Thought I'd try to go the direction that NotoriousVR was suggesting, and set the "cam profile map" to all 1.  He said maps, as in plural, and I wasn't sure exactly which maps he was talking about, so I thought I'd give KFPBRK a try at all 1's. This didn't seem to help any. Also, don't pay attention to the boost overshoot or the lean top end AFR, those are due to other unrelated tweaks.  The AFR around 3800-4100 is still a funky shape.  There seems to be an irregularity with requested boost here as well, and I'm not sure how much of it is related to my changes in the boost stuff or the changes in cam switchover, but it looks like at least some of the weirdness around 3800-4100 can likely be attributed to the cam switchover.








So, here are some questions/thoughts that I have (any input/discussion is encouraged):

1. In the S4 wiki it says, "abrupt changes in requested boost near the MAP limit can make the boost PID unhappy."  I'm only boosting ~15.5 psi, so I'm nowhere near the MAP limit.  How relevant is the MAP limit to this discussion?

2. Has anyone played around much with KFNW/KFNWWL, and what has been your results (Julex?)?  We can't look into the RS4 files for any insight into 2.8 cams or bigger turbos, as they have a completely different KFNW/WL scheme, with many maps we don't have.

3. NotoriousVR, which maps specifically are you setting to 1 to cure the requested boost part?

4. If fnwue dropping from around 1 to around 0 is indicative of it being a cam switchover issue, what behavior would fnwue ideally have?  It's got to drop to around 0 when NWS is activated, no?

5. Obviously the load notch and requested boost notch are related, but it seems that what fixes one may not necessarily fix the other.

6. KFPBRK/NW have pretty poor RPM resolution up around where the notch is for my turbos (3000, 3800 and 5000 are the RPM rows, whereas down lower in the rev range the rows are separated by 250-500 RPM). Any thoughts on possibly changing the axis for better resolution up there, or bad idea because the resolution is needed down low?

7. The biggest question of all, WHAT SPECIFICALLY HAVE YOU DONE TO FIX THE LOAD AND/OR BOOST NOTCH IN YOUR OWN FILE?  WHAT HAVE YOU FOUND WORKS, OR WHAT HAVE YOU FOUND DOESN'T WORK? (and make note of what setup you're running)

All four KF maps you grouped below are used to calculate amount of residual cylinder pressure dependent on NWS state and is directly then used to calculate load and (I think) maf voltage to g/s conversions. Log MAF sensor voltage and you will see that there is no notch there....

To be honest I don't exactly remember what I did but it was hackish. I would like to see if anybody has ideas on that. Oh... and this doesn't show when you run underscaled maf.

The factor fpbrkds_w for the calculated combustion chamber pressure prb_w is calculated from KFPBRKNW and KFPBRK.  pbr_w is the main input for rl_w.

fpbrkds_w is (1 - fnwue) * KFPBRK + (fnwue * KFPBRKNWS).

In my opinion, smoothing this transition will correct this.

The other maps that have been mentioned regarding this are not actually influenced by cam changeover. The bit b_nwvs is set if SY_NWS > 0.

If the notch was the result of a torque function (i.e. KFZWOP(2)) it would manifest in target load not actual.

I don't actually think it matters much if there is a notch in actual load on cam changover. In fact, it may be accurately modeling load anyway (which is probably what you want).

Unless, of course, you are logging fueling numbers you dont like (via wideband, not IDC or on time) ... as in the OP, who was seeing some odd wideband numbers near the cam changeover point.

My issue (as described in the wiki) was a notch in requested BOOST, which (as I said) was very problematic for the PID near the MAP limit, and particularly in the region where there is the most amount of wg change activity (peak boost)

If we do solve the fueling problem, somebody remind me to update the wiki

What do you think about my situation, where a notch in requested boost was introduced when I have 0% WG DC and am well below the MAP limit?

I was hoping more for some input on your thoughts of how the notch correlates with the MAP limit/WGDC, as my file takes those out of the equation. Trying to figure out the base cause and solution of the notch in general.

Which brings us to this:

On cam changover, it appears as though there is a discontinuity in the MAF readings. I am assuming that is because the amount of air being injested REALLY does change at that point.

So there are probably two different corrections that are happening

1) correct rl_w as calculated from MAF based on cam position
2) correct plsol as calculated from requested load on cam position

Is it possible to override 2 (deliberately) without screwing up 1?

AND

Is there an additional requested load correction based on cam position?

And the notch at 4k is even visible here in APR stage 2 logs: http://www.audizine.com/forum/showthread.php/482031-devils-own?p=7520007&viewfull=1#post7520007