BNR S4 build from Oz, advice needed!

[Datsam76]

Hi guys,

I'm currently in the process of installing a BNR S4 on my 2011 MS3, current mods include:

BNR S4
HTP 3 INCH TIP
CP-E CATTED DP mated to stock cat-back
UPGRADED HPFP INTERNALS
GRIMMSPEED EBCS
VERSATUNER

I have got my MAF CAL to a point that I'm fairly happy with, fuel trims and AFR targets look ok. My issue at the moment is what I think to be a VERY slow spool, the car does not feel responsive AT ALL. In a 3rd gear WOT log im not seeing my full boost of 18.5psi (wastegate spring pressure in my case) til 4200rpm. Looking around a lot of the BNR s4 guys are seeing this at or before 3500rpm.
My initial wastegate spring pressure was set at 17 psi but after contacting Brian from BNR he suggested shortening it 2 full turns which I did and it did improve it somewhat (initially I had even slower spool). I dont want to go any shorter or my base boost will be too high.
In an effort to try and spool it earlier I have even put wdgc to 100% all the way to 4000rpm and it doesn't make any difference. I have bench tested my EBCS and it is working correctly, I have triple checked the vacuum/boost lines. I have done boost leak tests and have no leaks anywhere.
One curious thing I have noticed, when the car is dead cold, it has far greater response, spool time is greatly reduced, it seems to get worse as it heats up, I have not yet captured a log for comparison though.
The tune im using as a starting point is the OTS versatune Base 93 Octane high load.

I am quite new to the tuning side of things and I understand the tune will have a lot to do with effecting the characteristics of turbo response but my gut feeling is that I have some issue somewhere. I have searched countless threads to try and come up with an answer but so far it has proven fruitless.
Here is a log of a 3rd gear WOT pull to show you the turbo (lack of) response.

[ATTACH]234044[/ATTACH

One thing Im not sure if its normal, the MAF g/s curve doesnt look smooth?

Looking forward to some knowledgeable people to chime in and offer some advice on my issue

[BenderIsGreat]

Your accelerator pedal position is showing as 67%. Either I have my typical values for that field mixed up, or you’re not at WOT.


Sent from my iPhone using Tapatalk

[Fstrnyou]

While the APP tops out at 67, which is odd, the relative throttle eventually does get to 73 at around 4400.
With APP being so "low", your tune is likely targeting a lower load. You may want to check your throttle calibration tables.

[VoodooJef]

That is a trait of Versatuner (the APP thing). To make a long story short, it`s opening the same amount as it would be with an AP. It doesn`t affect anything, but it you really want to mess with it there are a few solutions. The truest solution is to grind off the small bump on the back of the accelerator pedal arm that prevents it from going all the way to the floor, but even with it completely gone the highest the APP will be is about 82%. 80% is as far as it is physically capable of opening anyway.

With that said, there are several things in a base map that would cause your turbo to spool slower. Timing and VVT being two big ones. With a 100% load based tune you will see it spool differently. I couldn`t explain why, it`s just the case. You`ll still see the same power numbers, and nearly the exact same curve even with a different boost plot. Again, I only have the facts, not the reasons behind that one. (there are two member on here, both friends of mine with nearly identical hardware. Both on 93 had almost identical power numbers and dyno curves despite the VT map bringing in boost on a totally different plot).

[Datsam76]

Thanks for your input guys, I really appreciate it!

Yes I was aware of the 67% APP trait in Versatuner, I read about it over in the Versatuner forums.
I was wondering how much of effect timing would have on turbo spool, thanks for that! I haven't played with timing yet as I want to make sure everything is as it should be before I venture into that territory.
And the VVT - I have read that that can gain you another couple of hundred RPM earlier spool, but again, Ill leave fiddling with that until i'm certain everything else is in check.

Great info on the different boost curves but same power curves, that's not something I had even considered. There's my inexperience showing..

I think Fstrnyou has hit the nail on the head in regards to requested load. I went in and checked and at first it didn't seem too far off but then it dawned on me... There are the requested load by gear multiplier tables, which when these were applied to the calculation, netted a much lower requested load. If my logic is correct, that's why my throttle was closing??
I guess this is set for the much faster spooling K04 so it doesn't overshoot its load target when accelerating? Please correct me if I'm wrong.

Anyhow, I made some adjustments to the load targeting tables and the car feels a lot stronger, boost comes on with more of a punch. I am still getting a slight reduction in throttle at around 3500rpm but its much better. Here is another 3rd gear WOT log after the changes.

3RD GEAR WOT - 2.csv

[Fstrnyou]

Is that throttle issue just for the 3's?
I hit 100% APP.

[Datsam76]

As far as I'm aware, its just the Gen 2 MS3's.

[Fstrnyou]

Wouldn't it be easier to scale the throttle calibration so 67% is WOT?

[VoodooJef]

Originally Posted by Fstrnyou Wouldn't it be easier to scale the throttle calibration so 67% is WOT?

That`s basically what the AP does, it just doesn`t tell you LOL.

To the OP, in regard to load tables: the ECU will only target the lowest load table applicable. Ie, if your absolute load table is maxed at 4, but your per gear target load is 2.1, it`s only going to hit 2.1.

Also, you can define when you get throttle cut and when you don`t. It`s a better idea to just get your load tables sorted to begin with, but it`s there. Something else to check is SWAS interference. Some cars are prone to it, others are not. Mine absolutely shits the bed if I don`t disable it (it is a very simple process. You can either unplug it altogether or you can wire in a switch). In your logs, look for a sudden spike in Injector Duty Cycle (idc) and/or a substantial cut in timing between approximately 4400 and 5600 rpm. It will also show up as a huge drop in AFR if you load the log into virtual dyno.

[Fstrnyou]

For me, the DBW overload tables don't work. I was targeting 1.77 load at 3k. Logs showed the relative throttle increasing as I flew by the load target...right up to 2.1 where I hit fuel cut. Even though my DBW overload table was asking for throttle cut.

In the end, I was just being lazy and trying to avoid reducing wastegate spring preload. I gave up on that strategy and will be adjusting it after work today.