Subaru Boost Control Systems - EXPLAINED | Subaru ECU Self Tune Module

How boost control works on a Subaru Impreza, Forester or Legacy.
Live stream explanation of the hardware and software control systems for Subaru boost control. Including how 2 port and 3 port boost solenoids work and how to control boost using the standard OEM ECU when tuning the ecu.
I will take questions on boost control issues on the std ecu and how to solve them.
website: www.racedynamix.com
bookings: racedynamix.as.me
merchandise: racedynamix.teemill.com/
#racedynamix #subaruremap #subarutuning #subaruboostcontrol

[@user-nf3oq2ge3g]

I do know once you hit your target boost curve. The turbo dynamics tables will help get boost in low gears and help take boost away in higher gear loads to actually compensate correctly. Some tuners get lazy and high high boost target values but really taking the time to map your boost curve and use the boost controller To help achieve that. This is great info just knowing what each map does and getting insight from many people

[@racedynamix]

Yes, exactly that. if you log what boost wgdc is in say 3rd gear when it is hitting its boost target, set the max wgdc a little over that so it has room to achieve the boost in lower gears using the TD tables to make up the difference. In higher gears the TD tables are used to bring it to the target 👍

[@user-nf3oq2ge3g]

@@racedynamix people underestimate the power of research and I am way meticulous in the boost curve region probably more than most and everyone at first, gets irritated that I’m taking so long but the difference in gears and load make the biggest difference in a tune. And taking advantage of the closed loop boost system to work to your advantage is the best route. Your spot on with your tuning for sure.

[@scoob_dj]

Really enjoying these Duncan, very insightful. Looking forward to the next one already.

[@racedynamix]

Thanks mate.. Appreciate it 🙏

[@nickgandy3]

Really enjoying these videos. Thinking of coming to see you in a couple weeks to get my 05 sti mapped once I've finished all the mods with eks

[@racedynamix]

Go for it 👍 Thanks Nick. You're in good hands down there 😎

[@michaelkazi]

Very well explained.

[@racedynamix]

Thank you very much Michael 🙏

[@Scoobypaul75]

Hi Duncan. Great video. I’ve got a v3 jdm sti running esl. I’m self taught on tuning this platform myself and have always kept the min and max duty tables the same. I’ve managed to control boost pretty good thus far but after watching this video I think. Will be able to fine tune it much better so thank you. It’s very hard to get knowledge from reputable tuners. I’ve done a lot of work on my car ie g25 550 turbo. Front mount. Fuel pump., for, RCM head gaskets and RCM extreme head studs and water meth injection. I’ve managed to set it all up and running at 1.9 bar of boost for around 12 months. As I’ve added more I’ve increased the size of the injectors. The most recent upgrade I’ve done is 1000cc Bosch top feed injectors with parallel fuel rails. Whenever I’ve increased the size of the injectors I’ve kept the injector scale at 1 and then completely remapped the fuel map to suit. Really struggling with cold start and warm start with these injectors. I’ve tried all different iterations of injector scale and maf sensor scale with the same result I know there’s tables I can’t access using esl but wondered if you could give me any tips to help with this problem. I’m running speed density too. Cheers.

[@Scoobypaul75]

Oh yeah I’m in Australia too so no help here unfortunately.

[@racedynamix]

Hi. Thanks for the comment.. 🙏 I don't know whether the version of the software that you are using has the integral and proportional tables exposed but they will make it easier to fine tune the boost. By running the initial and max the same you are effectively running it without the closed loop control so would get varying levels of boost per gear or load. The limitations of the ecu are stopping you getting the cold and warm start right unfortunately. As well as cold and hot start tables not being accessible, the tip in tables are not available for change either (ie what happens with large changes in throttle) and that makes tuning larger injectors a real battle. Personally I would congratulate you for getting that far but recommend a more capable ecu as it will work with you rather than against you. Sorry. If you wanted to stick with the Esl.. The fuel multiplier is the key to those hidden fuel tables so would run something like a multiplier of 0.5 that would be applied to cold and hot start enrichment tables.. And tip in.. Then redo the fuel tables in their entirety. Hth

[@Scoobypaul75]

Thank you so much for the reply I really appreciate it. Yes I definitely need to be able to access those other tables. At low throttle when you take your foot off the pedal it jerks pretty bad. Fortunately this car is just my toy so driveability isn’t my main concern although would be nice. Can you elaborate on the fuel multiplier? Is this a table. Can access? As I thought I had been in every table? Cheers

[@racedynamix]

@@Scoobypaul75hi.. Knowing that behind the scenes there must be other tables that dictate how much extra fuel is added for cold start, a smaller amount of fuel for hot start and various extra amounts of fuel for throttle changes (they are not hidden on purpose by Esl just not discovered or reverse engineered tbh) These tables MUST exist as they do in all ecus so working on the premise that your 1000cc injectors (mostly these flow at 900cc tbh) are about double the size of the std 440cc.. Using that multiplier of 0.5 then that will apply to all the fueling tables that you can see AND those you can't. It will be a painful and laborious process getting it right but if it were me I would be on the lookout for a second hand Link G4 if budget allows.. You will thank me for it later 😉😁

[@Scoobypaul75]

@@racedynamix Hi yes. I spent last week completely retuning the car with an injector scale of 0.6 instead of 1 and to be honest the end result was the same. Can you go below 0.5 or is it limited to 0.5? Cheers.

[@nickyear-w7749]

Thanks again I adjusted my maf scaling . I started at 4g/s instead of 1.4 afrs are much richer on the bottom end of the scale.

[@racedynamix]

Hi.. Too big a change imo. I will do a video on this at some point but a brief explanation here is.. If you have a value for the maf reading of 1.4 g/sec and the ecu is having to add 25% at least to get it close to the right lambda ratio to idle.. Then add 25% to 1.4 or to the whole range for the initial 0.87 start value probably through to 2 g/sec then blend the curve so that it looks logical.. Try that and repeat until it is close 👍

[@user-ul6kk1vp7r]

Very informative, keep up the good content. A question with the 3pbcs. Do you still have to use the restrictor pill?

[@racedynamix]

Thank you 🙏. No restrictor pill needed with the 3 port 👍

[@luke555wrs]

Good explaination of the control processes for the later cars. How does it work for the classic ecus MY1999 and does a later piesburg 3 port work with them to provide better boost control.

[@racedynamix]

The 99/00 is similar to the bug wrx example but more crude in its control in some ways. A pierburg 3 port works well on these in my experience (they are never a bad idea though) as it can react quicker to target boost versus boost error iterations.

[@robj2502]

Hi there, I am part way through a pretty substantial overhaul to my recently acquired 2003 spec C and due to some damage/wear to the VF36 turbo fitted it is being upgraded/hybridised. As part of this I have been looking into exhaust upgrades as current system is a bit of a hotch potch of bits and in poor-ish condition. So a couple of questions: Assume that a 3 port would be required to control the upgraded turbo? if so with the 3 port fitted would the car be driveable ie: it would work exactly the same as the standard 2 port to allow for getting the car to the location it is being tuned? Given the engine is remaining standard would it be best to fit a 3inch or 2.5 inch system (turbo spec I think is billet compressor and VF42 turbine - might have this the wrong way round but sure you understand) are their pros and cons to either size from a power/response perspective? lastly assume turbo, exhaust and uprated fuel pump are fitted before tuning would the car be safe to drive to tuning location as long as it was driven off boost? Thanks for your time and have really enjoyed your videos - keep up the great work

[@racedynamix]

Hi Rob. Thanks for watching.. You will be fine to drive off boost to mapping with a 3 port, fuel pump and exhaust changes. I would go 3 inch 👍 Hth 😁

[@fredastaire6156]

I wonder if the stock ECU can run dual fuel injectors (x4 ports/one rail)? Do you know, by chance? I'm looking to add a Radium dual fuel injector set up to my 04 STi

[@racedynamix]

Not as far as I know it isn't possible of it. Tbh I am not sure why you would want 8 injectors when the top quality top feed injectors have great flow and spray pattern at low idc. I ran 4x ID 2000 injectors and that idled lovely even with cams. Adding another 4 injectors doesn't seem anything other than expense for no benefit and lots of pitfalls/complications in controlling them. I am sure that fuel rail set up is great but sorry.. I don't see the point.

[@oldfashionedwrx3574]

is it acceptable to close WGDC until like 3000 - 3500 RPM, say 100% duty cycle to get as fast spool up as possible on a VF28. I imagine you make a lot more low end torque which probably wears things out a lot faster VF28 seems to spool very fast this way but you use a lot of fuel going into the boost fuel map a lot

[@racedynamix]

It is possible to do that but running 100 duty almost always leads to overboost wobbles in boost. Better to set properly and set realistic boost targets so as to not overload the integral side of the boost control strategies.

[@user-rr3ng9ls1d]

Hello Duncan. Please tell me, the boost after 5000 revolutions decreases from 1.1 to 0.8 bar. Westgate duty does not help to keep the boost higher. Do I probably need a stiffer actuator spring?

[@racedynamix]

If its a small td04 on a 2.5 engine then pure physics means it cant keep supplying boost enough to hold that pressure. In reality even with a stiffer wastegate spring it may not and even if it did it would be outside of its efficiency and would just generate heat rather than power. Hope that helps

[@user-rr3ng9ls1d]

@@racedynamix ihi vf48, grimmspeed salenoid, 3 inches exhaust. Anyway, thanks for the reply😀

[@paulstead-ge5jj]

Q for what reason can a hawkeye not have antilag?many thanks.2.5 wrx 07 plate

[@racedynamix]

Hi. It is possible but unf3not on the std ecu set up. There are patches available to do it but there are significant compromises on the std ecu. Aftermarket ecu is the way to go for the toys 👍

[@madmuffin12345]

hello, I've fitted a boost gauge (03 blob wrx) and the i followed the instructions and I'm 99% sure I've done everything correct. which it t's of the vac lines after the stock t to the inlet of the (stock 2 port) boost controller ive noticed that it wont go any higher than 5psi (stock turbo). am i right in thinking that the actuator is just being forced open as i have a 3" exhaust all the way through. the car doesnt really start to pull until about 3k rpm so am i on the right track in thinking a 3 port controller is needed?

[@racedynamix]

Hi - Connecting the boost gauge to the solenoid to turbo or actuator hoses will never give an accurate reading. It should be connected (via a T piece) to a vacuum line from the manifold. Ideally the one to the dump valve would be best. It is possible that the 5psi is correct but the gauge should not be plumbed to the boost control pipework. My best guess as to why your boost is limited to 5 psi is that you have replaced the vacuum hoses from the turbo and not spotted that this line has a small restrictor pill in it. I show it in the diagram on this video. If it is not there then get hold of one :) I very much doubt whether a 3 port is needed on a blobw wrx. They rarely are in my experience. HTH Duncan

[@madmuffin12345]

@@racedynamix yeah the pill is still fitted ill get the vac lines changed about and see if its just because of the incorrect install on my part. thanks for getting back to me so quickly your videos are amazing for someone who's just starting out in to modified cars. thanks again !!

[@racedynamix]

@@madmuffin12345 is the pill on the turbo side of the t piece? If it is, and 5 psi of boost is right then it may be in limp mode to protect itself.

[@madmuffin12345]

@@racedynamix hello, I’ve finally got round to having a play about with the vac lines. After relocating the pipe to boost gauge to the pipe on the BOV and also replacing the vacuum line on boost control solenoid and fitting the refitting the restrictor pill ( i found it in my parts bin lucky I don’t throw anything out) the car is now running pull boost again the car does creep up to 15-16 psi for a split second when building boost but settles around 13-14 psi should be concerned about the little boost spike when building boost?

[@intergrale4x4]

Great Video topic but could you please make the boost detail images full screen while you are talking about them please ?? I'm struggling to see the details and numbers even with my specs on :)

[@racedynamix]

Thank you.. Will try my best to make it clearer. Eventually I will up the screen resolution for the live stream which should help 🙏

[@user-ravenxv]

so recently I've been thinking the wastegate control is dynamic, and not binary, as in the ecu works it like a valve the way tvis would until wot. is this right? or is it really just closed or open?

[@racedynamix]

It cycles the solenoid 15 times a second.. The movement of the arm is pressure dependant so when the solenoid is not powered the air diverts to the wastegate. The ecu control duty.. Ie the % of time that the solenoid is powered 👍

[@user-ravenxv]

@@racedynamix excellent thanks!

[@tdro98]

So if I put a 3port on is it better to drive with it disconnected electricity before I get a tune ?

[@racedynamix]

HI. No...That will bring up an engine light. Off boost it will be fine to drive to your tuner even with it connected. HTH

[@bigredwrx4313]

Hi mate I've got a bugeye wrx running a vf34 turbo this open sourced tuned, it's only making 197kw ,ive got a Jun wastegate which is a bolt on to a stock vf34 it's good for 17-19psi will this benefit me at all for better boost I'm also running the stock boost controller

[@racedynamix]

Hi. Whst boost are you getting at present?

[@bigredwrx4313]

@@racedynamix 17

[@racedynamix]

@@bigredwrx4313 seems that power is low for that amount of boost to me. Is it really low octane fuel?

[@bigredwrx4313]

@@racedynamix 98 octane here in Australia premium

[@bigredwrx4313]

I kinda just want to know what changes will happen if I put that Jun actuator in

[@kcsmostwanted29]

Hey there I am currently in the middle of an e tune and I recently just did a bunch of mods including cobb 3 port, cobb turbo inlet, ets fmic, fuel mods etc. I am still running a stock turbo and stock wastegate and I am having an issue with overboosting with 0% wastegate duty cycle. So my tuner advised me to check my vacuum hoses going from the boost controller to the wastegate and I didn't see any issues with it but I went ahead and changed the hose anyway. Forgot to add I have a 2013 wrx usdm but I was hoping you could give me any advice or suggestions I could try to get this figured out? Thanks so much for your time! Love your videos!

[@racedynamix]

Easy way to test whether you have an issue with the wastegate is connect 1 hose direct from turbo vac nipple to the wastegate vac nipple.. This should give you wastegate pressure.. Approx 7psi of boost. If it still overboost then either a jammed wastegate or split diaphragm in the wastegate. If this does solve it then the 3 port was plumbed in incorrectly. The port on the front should come from the turbo vac nipple. Blow through that port and the air will come out of the port that needs to be connected to the wastegate. The other port either vents or goes into the turbo inlet 👍 Thank you BTW 🙏

[@kcsmostwanted29]

So I've double checked my plumb job on the cobb boost controller and everything is ran correct so to do that test you described when connecting those two nipples to the wastegate to turbo do I need a to do a pull or let it idle? Also when I did my first datalog for the tuner at 50% throttle I had good wastegate response on the datalog but when I did the WOT pull it was 0% wdc thru the whole pull so idk what the deal is I hope my wastegate isn't going out....thanks so much for the advice I can't thank you enough, hard to find good people like you anymore so thank you again really!

[@racedynamix]

@@kcsmostwanted29 you will need to do a pull with that test. But yeah take off the 3 port hoses from the turbo and actuator and replace with 1 single hose that goes between them 👍

[@kcsmostwanted29]

Hey there sorry to trouble you again...I've done just about every test I can do including your recommendations and I am just stumped. I tested ohms and voltage of the ebcs tested pressure on the wastegate and it seems to be opening and closing and I'm still overboosted with 0% WGDC. Again I apologize to bother you again about it but I just don't know what to do..

[@racedynamix]

@@kcsmostwanted29 did you connect a single hose from the turbo to the wastegate (removing the 3 port pipework)?

[@douglang4615]

Hello Duncan . Question Why do I get detonation . Well my cell light shows it. Not on the power . Almost steady . 2800rpm Also had it at 3800 . Not sure how u could have detonation, if she isn't really pulling .. more like steady cruise . Thank you Regards Doug

[@racedynamix]

Hi Doug. How are you telling that it is detonation?

[@douglang4615]

@@racedynamix Hello Duncan I didn't have my det cans on. I have set up my cell light /eng light to flash when it sees detonation . So it gives me an indication, even when I am not listening for det.

[@markarlie7644]

Just a thought, dump valve springs, is there a guide on what spring for what power, ie the oem spring in a dump valve, is it rated to a certain bhp ?.

[@racedynamix]

Personally I hate dump valves and most often blank them off entirely on my own cars 🤣 The std dump valve is fine and has a much stronger spring than most of the aftermarket ones available. I don't think a guide exists tbh.. I certainly have never done one. If you understand that the spring inside is assisted by the boost pressure pushing it back in there is no reason why a decent dump valve or even the std one can't handle some very high power. Hth 👍

[@markarlie7644]

@racedynamix now then .. without opening a an of worms, a complete blank of , I always thought was bad for the turbo? Waste air retuning to turbo etc. I do quite like the sound of a blanked off turbo , but always thought it would cause damage / premature wear to the turbo unit etc.

[@racedynamix]

@@markarlie7644 all the good things in life aren't good for you or the car 😉

[@mattbelka1]

TDynamics initial and proportional should be as close to 0% but what is acceptable figure my1 are like 2-5% is that too much ?

[@racedynamix]

They should never be 0 imo as different loads in different gears means that the PID needs to be doing it's thing to control boost. Focus on the result.. Is boost reaching target smoothly in various gears?

[@mattbelka1]

@racedynamix yes it dose but I focus in initial wgdc to make it as close to rich target so TD don't do much work in perfect run they are like 2-5 % but that all depends from run how I do step on gas or IAT etc. Car is 05 jdm sti

[@mattbelka1]

@racedynamix some times td are proportional 2% and continues are like 8 I keep TD stock values and trying just adjusted with initial wgdc and I'm keeping 10% different between max wgdc

[@mattbelka1]

Boost set on 5th gear and all pulls...

[@racedynamix]

@@mattbelka1 in the jdm sti rom you also have the gear by gear tables which I would use in that situation to enable the heavy lifting.. Eg add 10% in 2nd gear, 5% 3rd 2% 4th..and maybe drop it down in 6th by - 5% Sounds like you are on exactly the right track with the rest 👍

[@user-nf3oq2ge3g]

Man to have switchable maps on my car like my Cummins truck would be nice. The Subaru is just 1 tune at a time so even when the wife drives it it has 400 wheel torque. Or the kids borrowing the car. And one month later my new tires are down to the wires haha

[@racedynamix]

Easy to rig something up to give high and low boost... I see a video coming on for this 😂

[@user-nf3oq2ge3g]

@@racedynamix IV read about it but seeing it happen would be awesome. Especially where I live because I have to drive with my fuel drums 100 miles and get e85 ethanol in bulk. And when we are out, it would be nice to have the switch for the wife who does not even dare flash anything on the ecm. But I’m confident she could flip the switch when she put 92 in it and then back to the ethanol tune. I do know in the 06 sti system that it could possibly use high add tables and low add tables, to have it switch automatically but unfortunately I believe it relies on knock to switch between maps and it could end badly that way.. and the lack of a ethanol content sensor from factory makes it hard in the factory ecm. For 06 sti anyways

[@nickyear-w7749]

So i have an issue sometimes my car will over boost even though its set to 13 psi and it happens only in 4th gear.

[@racedynamix]

Hi Nick.. I think your turbo has a case of boost creep as iirc the wastegate duty was very low in your logs or possible even 0 at the top end. Solutions for you are either run a higher boost target and be thankful that it can hold the boost or port the wastegate on the turbo (or weaker actuator spring.. Or both) so that it can control a lower.boost better. Hth

[@nickyear-w7749]

I'm here

[@racedynamix]

Cool.. And welcome back Nick 😎

[@yehornaumov5893]

Ok my question is if actuator spring is 15psi And boost valve open how do tuners achieve 20psi 19psi and so on if oem spring can hold only 1.1 bar of boost?

[@yehornaumov5893]

Do you actually up grade actuator every time you up boost?

[@racedynamix]

Easy.. The 2 or 3 port boost solenoid diverts air back into the inlet rather than pushing against that spring. Air will always take the easy option. Hth 🙏

[@yehornaumov5893]

@@racedynamix thanks

[@racedynamix]

@@yehornaumov5893 my pleasure 👍

[@AmirPomen]

6am here 🤘😂

[@racedynamix]

Crikey. It is very difficult to set the right time to go Live with people watching in USA, Australia and Europe.. Let alone you guys in between these extremes of time zones... Hopefully it works for you on replay 👍

[@AmirPomen]

@@racedynamix no worries on the live timing...after all u mainly need to cater your local customer even more than some of us overseas... We all really thankfull for u willing to share all those info in the first place.. 👍👍