how-to: ECU-based direct boost control
Dec 9, 2012 | 07:10 PM
#1051
Just in case you didn't know, should we specify some basics?...
The boost solenoid is a valve that will prevent the wastegate from receiving true pressure by closing the line to turbo outlet pressure. This will make possible boosting a higher pressure than the wastegate actuator spring (12psi).
Wastegate duty cycle: the boost solenoid valve cycle On/Off at a frequency near 20 times per second. The WGDC value is the percent of time of this cycle that the valve is shut. So at 100 WGDC, the valve is shut 100% of the time. At 50%, the On and Off times are equal. That's how you control boost.
(I had time to lose
)
The boost solenoid is a valve that will prevent the wastegate from receiving true pressure by closing the line to turbo outlet pressure. This will make possible boosting a higher pressure than the wastegate actuator spring (12psi).
Wastegate duty cycle: the boost solenoid valve cycle On/Off at a frequency near 20 times per second. The WGDC value is the percent of time of this cycle that the valve is shut. So at 100 WGDC, the valve is shut 100% of the time. At 50%, the On and Off times are equal. That's how you control boost.
(I had time to lose
)
Dec 9, 2012 | 07:13 PM
#1052
I am with Raptord on opening this up for some debate.
To me it may not be an issue to someone who simply dd's or does the occaisional un-sanctioned race, but to say a track day, tt, or road racer it may be an issue. Especially late in a session or race when everything is hot already and maybe the turbo starts getting outside of its efficiency range trying to hit a desired load.
Not saying it would but..... what if?
To me it may not be an issue to someone who simply dd's or does the occaisional un-sanctioned race, but to say a track day, tt, or road racer it may be an issue. Especially late in a session or race when everything is hot already and maybe the turbo starts getting outside of its efficiency range trying to hit a desired load.
Not saying it would but..... what if?
It would ensure even track times/power ... on hot car yes it could be harder on the turbo
it also maintain much more consistency with the fuel and timing maps and makes the tuning be easier.
Load is calculated for a reason and it's useful to take advantage of the variables that comes into play.
Last edited by domyz; Jan 4, 2013 at 05:09 PM.
Nov 17, 2013 | 10:17 PM
#1053
Evolving Member
Joined: Jul 2007
Posts: 172
Likes: 1
From: Australia
Just wondering if anyone has seen 1.5-2psi differences in boost from just a 0.5% change in the WGDC table? I'm a bit surprised at how sensitive the boost is to WGDC changes...
Mods are Grimmspeed 3 port, Evo 9 turbo, Kando 18psi actuator preloaded, Tomei Pon-R 270's and usual intake/exhaust mods. Boost target is about 24psi, but it jumps between 23-25 at 4250rpm with just a 0.5% WGDC change.
Perhaps I'm being too fussy! But I haven't seen this with other cars
Mods are Grimmspeed 3 port, Evo 9 turbo, Kando 18psi actuator preloaded, Tomei Pon-R 270's and usual intake/exhaust mods. Boost target is about 24psi, but it jumps between 23-25 at 4250rpm with just a 0.5% WGDC change.
Perhaps I'm being too fussy! But I haven't seen this with other cars
Nov 18, 2013 | 08:49 PM
#1054
Just wondering if anyone has seen 1.5-2psi differences in boost from just a 0.5% change in the WGDC table? I'm a bit surprised at how sensitive the boost is to WGDC changes...
Mods are Grimmspeed 3 port, Evo 9 turbo, Kando 18psi actuator preloaded, Tomei Pon-R 270's and usual intake/exhaust mods. Boost target is about 24psi, but it jumps between 23-25 at 4250rpm with just a 0.5% WGDC change.
Perhaps I'm being too fussy! But I haven't seen this with other cars
Mods are Grimmspeed 3 port, Evo 9 turbo, Kando 18psi actuator preloaded, Tomei Pon-R 270's and usual intake/exhaust mods. Boost target is about 24psi, but it jumps between 23-25 at 4250rpm with just a 0.5% WGDC change.
Perhaps I'm being too fussy! But I haven't seen this with other cars
Did you boost leak test? A boost leak could cause the variation you are seeing.
What Blow Off Valve are you running? It could be leaking again affecting your target boost.
What is your WGDC at 4000 RPM for your 24 psi target? I found mine spiked if I increased from 98 to 98.5% - solution was a stiffer spring and so I moved to a 25psi WGA to get the WGDC back down into a usable range.
Nov 18, 2013 | 09:53 PM
#1055
Evolving Member
Joined: Jul 2007
Posts: 172
Likes: 1
From: Australia
It was leak tested recently with no issues. BOV is a Turbosmart metal recirc type. Not sure if they are prone to leaking or not...
WGDC at 4000-4250 is only 55.5%. Note that we only just recently put this new actuator on his car, which made 15psi with 0% WGDC and no more adjustment available on the rod. His old actuator only managed 10psi, so I figured 15psi was better if we were chasing 23-24psi.
WGDC at 4000-4250 is only 55.5%. Note that we only just recently put this new actuator on his car, which made 15psi with 0% WGDC and no more adjustment available on the rod. His old actuator only managed 10psi, so I figured 15psi was better if we were chasing 23-24psi.
Mar 11, 2014 | 03:10 PM
#1056
Newbie
Joined: Jul 2012
Posts: 9
Likes: 0
From: Sydney, Australia
quick question in regards to the base boost low and high gear tables, in the original posts the guide says the max those tables can display is 24.6 but I notice the scaling for the JDM3-bar has a max scaling of 24.6 but my omni 4 bar map sensor scaling (which is what I have) it says the display max is 30.1 as per this scaling
<scaling name="psia8" units="psia" toexpr="x/(4.23*2)" frexpr="x*(2*4.23)" format="%.1f" min="0" max="30.1" inc="0.1" storagetype="uint8" endian="big"/>
Does this mean when setting the base boost and boost adder if I am aiming for 27 psi I can put 27psi in the base boost tables and just put my local atmospheric value in the boost adder table in my case 14.2 as my map sensor reads zero psi with just accessories on in evoscan with the formula set as 0.2369*x-14.2
Reason I ask all this is because I followed the guide originally and to aim for my 27psi set the base boost tables to 24.6 and set the boost adder to 16.6 ie 27psi + 14.2 - 24.6 = 16.6 and I was overshooting by 2-3 psi and hitting 29-30 psi but if I remove the boost adder it follows my baseline wgdc table
<scaling name="psia8" units="psia" toexpr="x/(4.23*2)" frexpr="x*(2*4.23)" format="%.1f" min="0" max="30.1" inc="0.1" storagetype="uint8" endian="big"/>
Does this mean when setting the base boost and boost adder if I am aiming for 27 psi I can put 27psi in the base boost tables and just put my local atmospheric value in the boost adder table in my case 14.2 as my map sensor reads zero psi with just accessories on in evoscan with the formula set as 0.2369*x-14.2
Reason I ask all this is because I followed the guide originally and to aim for my 27psi set the base boost tables to 24.6 and set the boost adder to 16.6 ie 27psi + 14.2 - 24.6 = 16.6 and I was overshooting by 2-3 psi and hitting 29-30 psi but if I remove the boost adder it follows my baseline wgdc table
Last edited by azzaevoviii; Mar 11, 2014 at 04:06 PM.
Mar 11, 2014 | 06:55 PM
#1058
Newbie
Joined: Jul 2012
Posts: 9
Likes: 0
From: Sydney, Australia
yes
this was how i had it during tuning of the bwgdc
this is how I had it after tuning and correction turned on, logged showed it overshot the targets but didnt try to correct at all during the run
this was how i had it during tuning of the bwgdc
this is how I had it after tuning and correction turned on, logged showed it overshot the targets but didnt try to correct at all during the run
Mar 23, 2014 | 02:44 PM
#1059
so im having a little trouble. my car is tuned on V7 with ecu boost right now, but i need to build up my old stock rom to match to use for inspection purposes.
i added the xml to my 88590015 xml but the addresses populating some of the boxes are not correct to start and the error correction/target tables are not appearing correctly.
what am i doing wrong? im wondering if i have some other mod on that xml i forgot about...maybe i should start with a clean one? i havent messed with xml in like a year so i feel dumb right now...
i added the xml to my 88590015 xml but the addresses populating some of the boxes are not correct to start and the error correction/target tables are not appearing correctly.
what am i doing wrong? im wondering if i have some other mod on that xml i forgot about...maybe i should start with a clean one? i havent messed with xml in like a year so i feel dumb right now...
Mar 29, 2014 | 02:54 PM
#1061
i'm having issues with tephramod ecu controlled boost as well. wgdc is logging what i'm telling it to do and i'm still only seeing wastegate spring pressure. i have evo 9 with grimmspeed 3 port. correction is zeroed out and i've checked the formulas multiple times. is there anyone i could send my rom and xml file to that would look it over for idiot errors please?
