Tuning for CST4 turbo

Shadowplane676

Shadowplane676

Greenie N00B Member
I am currently at a crossroads with my speed3. The stock K04 appears to have given up (won't boost past 4.5psi) and all signs point to the turbo (checked WG, BCS, boost leaks etc. and nothing showed up). I wanted to go with a CST4 for some headroom and not turning into a hairdryer at higher boost levels, however Corksport replied to an inquiry of mine that the CST4 is not a drop in replacement for the stock turbo from an ECU perspective.

I wanted to see if anyone had tuned a CST4 on either Mazdaedit or Versatune. I did see the Big Turbo thread, however it looks like that is primarily a base map to get someone to a dyno for further tuning (great thread BTW). Additionally, I have seen very little in the way of knowledge base items around for the Speed's ECU configuration and tuning. Coming from a standalone MAP-based ECU background, I am working on figuring out how the Speed 3 ECU differs and what tables affect the engine in the ways I am used to tuning. If anyone has further thoughts, resources or information along these lines' I'd appreciate it as I have spent quite a bit of time searching with no real luck. If I can't get up to speed appreciably soon, I will most likely end up rebuilding the stock K04 for the time being in order to get the Speed3 back on the road.

Regarding my choice of interested tuning options, I have a stable of 3 Mazdas that would benefit from the level of access a tune program would provide. I am not considering COBB at all due to the price per vehicle and lack of support for 2 out of 3. I am hoping that with this newer forum, there may be some knowledge floating around that was not particularly appreciated elsewhere. Thanks!

P.S. - I am working on recreating my build diary from the now defunct mazdaspeedforums.org site...
 
Shadowplane676 said:
I am currently at a crossroads with my speed3. The stock K04 appears to have given up (won't boost past 4.5psi) and all signs point to the turbo (checked WG, BCS, boost leaks etc. and nothing showed up). I wanted to go with a CST4 for some headroom and not turning into a hairdryer at higher boost levels, however Corksport replied to an inquiry of mine that the CST4 is not a drop in replacement for the stock turbo from an ECU perspective.

I wanted to see if anyone had tuned a CST4 on either Mazdaedit or Versatune. I did see the Big Turbo thread, however it looks like that is primarily a base map to get someone to a dyno for further tuning (great thread BTW). Additionally, I have seen very little in the way of knowledge base items around for the Speed's ECU configuration and tuning. Coming from a standalone MAP-based ECU background, I am working on figuring out how the Speed 3 ECU differs and what tables affect the engine in the ways I am used to tuning. If anyone has further thoughts, resources or information along these lines' I'd appreciate it as I have spent quite a bit of time searching with no real luck. If I can't get up to speed appreciably soon, I will most likely end up rebuilding the stock K04 for the time being in order to get the Speed3 back on the road.

Regarding my choice of interested tuning options, I have a stable of 3 Mazdas that would benefit from the level of access a tune program would provide. I am not considering COBB at all due to the price per vehicle and lack of support for 2 out of 3. I am hoping that with this newer forum, there may be some knowledge floating around that was not particularly appreciated elsewhere. Thanks!

P.S. - I am working on recreating my build diary from the now defunct mazdaspeedforums.org site...
Click to expand...


Well...... Versaturne works but it is not without its quirks. Yes it is cheaper so you have that but logging is generally slower and you need a laptop. I am currently running and tuning with Versatune. I will be doing a PI tune to make some jam this summer. The major issue I ran into on my last pass of tuning was that I was getting Load throttle when I was not even hitting my limits so I had to boost them higher, after that all has been well. I do wish I went AP to start with BUT I do really like the ability to tweak my tune and the maps not being on lock down. Pro tuners are awesome but I would rather tweak wgdc and random shit without paying for it. I did a full 93 and e30 tune on the CST4 on stock motor. My motor exploded lol However, that was due to some boost creep issues I was having with the CST4 and a tired old motor. If you have any specific questions I am down to help answer anything. @Enki is also very knowledgeable.

Yes, that thread was designed to get people on the road so if they needed to go work or just poor and could not afford a tune yet they could still drive their car "slowly".
 
I'm hoping Versatune is essentially a skinned Mazdaedit from a functionality standpoint. I'm definitely used to laptop interfaces though. My previous project car ran a Megasqirt-II ECU so it was completely laptop based. The trade-off between Mazdaedit and Versatune is with Mazdaedit, my breakover point at 3 vehicles gives unlimited vehicles whereas Versatune is still per vehicle licensing.

I don't suppose you did anything with a 91 tune on the CST4? Unfortunately Oklahoma only has a small handful of gas stations with 93, so 91 is pretty much the limit. Now that I have seen the base big turbo map, I am more tempted to get the CST 4, I would just have to keep my foot out of it while tuning....
 
Any pf these, Versatuner or Mazdaedit, can manipulate the factory calibration tables. This is all you need to tune for a larger turbo, for aux fueling, and so on.

If you are going to tune yourself then just start with a 91OCT/95RON base map, lower the WGDC tables to a safe value but still letting wastegate duty cycle to increase a bit in their chase for load targets, and work it from there.
The CST4 is similar to GT28 frame turbos if you're using Garrett as a point of reference. If your engine is healthy and you have the rest of the supporting mods bolted properly (at least HPFP, exhaust, intake, intercooler, bypass valve) then you will see pretty nice gains compared to a K04 anywhere above 4k rpm.
 
mituc said:
Any pf these, Versatuner or Mazdaedit, can manipulate the factory calibration tables. This is all you need to tune for a larger turbo, for aux fueling, and so on.

If you are going to tune yourself then just start with a 91OCT/95RON base map, lower the WGDC tables to a safe value but still letting wastegate duty cycle to increase a bit in their chase for load targets, and work it from there.
The CST4 is similar to GT28 frame turbos if you're using Garrett as a point of reference. If your engine is healthy and you have the rest of the supporting mods bolted properly (at least HPFP, exhaust, intake, intercooler, bypass valve) then you will see pretty nice gains compared to a K04 anywhere above 4k rpm.
Click to expand...
This

If you follow the guide I have for big turbo base tune once that is done do the following.

  1. Mafcal
  2. Set WGDC to 0
  3. Adjust Tune Limits so you do not hit them while logging but are still safe
  4. Set Load Targets high except for Load By Gear which you will use to tune.
  5. Set Load by gear targets to something safe , this will determine your boost sorta kinda as well
  6. If you are not hitting your load target adjust WGDC until you do , it will adjust as needed to reach targets but only as much as you allow it. There is a table for that.
  7. You will playing a balancing game of WGDC and Load By Gear Targets until you find you happy place.
  8. Once Load tuning is done you can start to add timing in small increments.
  9. Once you stop seeing gains from it or knock , stop and your back of 1-2 degrees and now you have a DD 91/93 tune
BABY STEPS, do not try and just get a final tune in 2 revisions, you will blow the car up.

This is just a quick jist of it. In reality you will want to look over all the tables and start to understand how they interact. As you tune and log and log and log and log you will start to get the feel of it. The big diff with load target tuning vs boost is that the car will adjust boost to stay at your target. So in theory you will see less boost in the winter "colder denser air" to hit the same load target. Where as people who boost tune only will hit the same boost target always no matter the air density. So load based tuning should be "safer" as long as the WGDC can keep boost creep in check when it is cold.
 
Thanks for the info! this is way more that I have been able to find previously. and I definitely understand that air density > boost pressure, and boost PSI is not the be all/end all of tuning. I have some thoughts and such below to see if I am understanding the interactions correctly compared to a MAP based setup.
  1. Mafcal -
    1. Currently I have the Mazdaspeed aftermarket MAF housing at 2.5". Would it be adviseable to up this to a 3" before a recal of the MAF sensor? The car also came with a 3" Turbo inlet duct behind the mazdaspeed 2.5" CAI/MAF system.
  2. Set WGDC to 0
    1. This essentially forces wastegate pressure i believe? On a CST4, i think the wastegate is 10 lbs, which is close to or below the OEM boost limit from what I recall
  3. Adjust Tune Limits so you do not hit them while logging but are still safe
    1. This is a new one to me, is this a software limit of some kind so the ECU doesn't go out of bounds on certain variables?
  4. Set Load Targets high except for Load By Gear which you will use to tune.
    1. So is this like a global load target with sub targets by gear? A la the stock 1/2 boost limitation?
  5. Set Load by gear targets to something safe , this will determine your boost sorta kinda as well
    1. Essentially a mid level limit, also used (as by OEM) to possibly reduce tire frying 1st gear scenarios
  6. If you are not hitting your load target adjust WGDC until you do , it will adjust as needed to reach targets but only as much as you allow it. There is a table for that.
    1. so the WGDC table is sort of like an authority table, if you hit max WGDC before load target, the ECU doesn't allow further airflow/boost. Interesting!
  7. You will playing a balancing game of WGDC and Load By Gear Targets until you find you happy place.
    1. Multi-level approach basically, global load targets, per gear targets then WGDC to meet targets. Raise targets slowly, paying attention to Fuel pressure, AFR, knock counts etc. Similar yet different to tuning a straight MAP based setup.
  8. Once Load tuning is done you can start to add timing in small increments.
  9. Once you stop seeing gains from it or knock , stop and your back of 1-2 degrees and now you have a DD 91/93 tune
    1. Timing definitely can be a touchy one, too much and knock/pre-ignition gets expensive fast.
 
  1. Mafcal -
    1. Currently I have the Mazdaspeed aftermarket MAF housing at 2.5". Would it be adviseable to up this to a 3" before a recal of the MAF sensor? The car also came with a 3" Turbo inlet duct behind the mazdaspeed 2.5" CAI/MAF system.
I'd recommend going 3.5 HTP or RamFab with the CST4 in cold weather you will be at the top range of the maf. You can keep the stock battery but will have to move the ECU. You will then need to set the inital mafcal for that size and go from there.
  1. Set WGDC to 0
    1. This essentially forces wastegate pressure i believe? On a CST4, i think the wastegate is 10 lbs, which is close to or below the OEM boost limit from what I recall
Yes this will put the wastegate at spring pressure, the CST4 spring pressure is like 17-14 lbs. You will need a better map sensor if you plan to go over 22psi as the stock one can't read past that. Which also needs adjusted in the tune. There is also a table that will adjust WGDC to help hit targets so if you set your WGDC to 0 and still see it logging at 20, that is that table kicking in to add 20 to help you meet target.
  1. Adjust Tune Limits so you do not hit them while logging but are still safe
    1. This is a new one to me, is this a software limit of some kind so the ECU doesn't go out of bounds on certain variables?
There will be load limits, boost limits, IDC limits etc etc. They will be set pretty well in a base tune but you will need to bump them up as you add power or you will hit them. Generally a load limit would be 1 over requested. Boost Fuel Cut would be like 3psi over requested and throttle cut would be 2psi. Something like that. The ECU will try it's best to keep you from blowing the car up if something goes wrong and is out of bounds. It is not the end all be all but it is helpful. You just don't want fuel cut kicking in when you are trying to tune the car and are still in safe stock block power range "under 400whp"
  1. Set Load Targets high except for Load By Gear which you will use to tune.
    1. So is this like a global load target with sub targets by gear? A la the stock 1/2 boost limitation?
It is by gear and by RPM for that gear. So you could set 1st gear to like 1.8 which might be 16lbs of boost sorta kinda to make that load. Which would stop wheel spin and get you some traction. You could then set 3rd gear to 2.2 load which would be maybe 24psi "not really but just to five an example" You want to ramp the load in as you don't need the car hitting max boost at 2krpm. Look over the base tune and mimic it.
  1. Set Load by gear targets to something safe , this will determine your boost sorta kinda as well
    1. Essentially a mid level limit, also used (as by OEM) to possibly reduce tire frying 1st gear scenarios
Yes, you can do this as explained above. I used to nerf 1st and 2nd a little to keep traction down.
  1. If you are not hitting your load target adjust WGDC until you do , it will adjust as needed to reach targets but only as much as you allow it. There is a table for that.
    1. so the WGDC table is sort of like an authority table, if you hit max WGDC before load target, the ECU doesn't allow further airflow/boost. Interesting!
There is a table that will adjust +20 or -100 WGDC. You can set this to whatever you want but that is generally good. This lets WGDC adjust to hit requested load in all scenarios. You generally walk WGDC and Load together to find where the WGDC wants to be to meet a load target. If you need to add +20 each time then the WGDC table needs to go up as it is quicker for the ECU to use the WGDC table right away and not make massive adjustments everytime you get on it. So if your table says 3k rpm 100% throttle 65% WGDC and on the log you see that you are at 76% WGDC BUT you are hitting your load target. Well then go into the table and set it to 70% wgdc there. You want your tune to be as close to optimal as possible but the ECU can and will adjust.
  1. You will playing a balancing game of WGDC and Load By Gear Targets until you find you happy place.
    1. Multi-level approach basically, global load targets, per gear targets then WGDC to meet targets. Raise targets slowly, paying attention to Fuel pressure, AFR, knock counts etc. Similar yet different to tuning a straight MAP based setup.
Yes very much this. Walk them back and forth to get where you need to be.
  1. Once Load tuning is done you can start to add timing in small increments.
  2. Once you stop seeing gains from it or knock , stop and your back of 1-2 degrees and now you have a DD 91/93 tune
    1. Timing definitely can be a touchy one, too much and knock/pre-ignition gets expensive fast.
Yes timing is best done in .5 increments and keeping a close eye on the logs.
 
Thanks all for the info so far. While I wanted to go with a CST4, various factors ended up changing the goal somewhat. I have had my stock K04 rebuilt by a reputable local turbo shop (balanced, new CHRA etc) for a reasonable cost. I believe I will still need to do some tuning with Mazdaedit as I will have added a few mods along with the rebuilt turbo. Those mods are
1) Catless downpipe
2) Corksport HPFP
3) Upgrading to a 3" MAF housing to match TIP and to remove poorly installed 2.5" CAI

I believe these mods end up allowing more airflow and will require additional fuel changes along with a MAF recalibration to not cause the motor to go lean.
 
I too have used a MS3Pro and have done flash tuning for the Speed3s.

Depends on the strategy you used for management on the MS2, but flash tuning is quite different due to the funky solutions/maps that the were programmed from the factory.

One major difference is that you are stuck with O2 targeting rather than VE/duty/PW. MAF is not a common practice in the aftermarket, but you are stuck with that as a load for flash tuning.
 
Well, I finally got MazdaEdit and started looking in to what tables are available and what logging is possible. I am still working on deciphering many of the tables, but I did find that the logging leaves a bit to be desired. It is not apparent which parameters are loggable in their lists of options. Fortunately, Versatune Free lets you log and has some of the items I cant find in mazdaedit, such as Boost air temp and more correctly identified sources for other variables. I am leaning towards logging with Versatune and tuning with Mazdaedit at this time until I find the right variables. Additionally, I have a sneaking suspicion someone has fiddled with this ECU before. There are a few tables that don't look right or appear that someone missed a cell or 5 when adjusting.

QcCtXJC.png


I do think I found concrete numbers for why under 45* ambient temp I hit boost limit. This morning (a 60* morning) full boost resulted in an Absolute Intake pressure of 2.09 BAR. In Mazdaedit, it appears the stock boost fuel cut limit is set a 2.12 BAR; only .3 BAR leeway.

Still planned is an upgrade to a FMIC and possibly a CST4 down the road. In teh mean time, learning to tune this combo on the stock K04 seems the best action for now.
 
As someone who has used all 3 platforms, ME is the worst one and has least support.

The "oem" maps ME had for the RX-8 were atrocious and had some very weird values, along with not being able to actually perform incremental changes on them. That whole missing cell and crazy presets is exactly what I would see there. VT/Cobb had no such issues, although there are SOME stock maps in either that just look bizarre. ME is also hard to uninstall/unmarry, if not impossible, IIRC, if you ever want to use VT/COBB later. I'm not sure how you can run VT to log once ME is installed, but if possible let us know.

The flipside is that ME along with VT may be the only one that will let you turn off various CELs, while I'm hearing that Cobb is removing that functionality for emissions related CELs. Compromises abound.
 
BAT-man said:
As someone who has used all 3 platforms, ME is the worst one and has least support.
Click to expand...

I can see why it is a bit more clunky than VT or COBB as the UI is definitely not as refined. However in my case, it was way more cost effective. I have 3 vehicles that I can use ME on, 2 of which COBB doesn't support or no longer supports (2016 CX9 and 2005 RX8) and VT doesn't support the CX9 at last I checked. From what I can tell, all ME does is adjust the OEM table values rather than replacing the code entirely (a la COBB). I believe this is also how VT works. For what I am looking to accomplish, this should be more than sufficient for my platforms.

Regarding Logging, using VT free is essentially an OBD-II logger so it shouldn't matter what edits are done to the ECU and by which software for logging to still take place.



The biggest thing for me at the moment is getting grips on the table relations and load based tuning vs the Speed/Density that I am used to. I plan on adjusting the base maps to achieve my end goal rather than taking an OTS and running it non-adjusted for the application. If I understand it correctly, I need to start logging engine load as a parameter to ensure I am staying below the limit of 2. If I reach the limit of 2, a MAF recalibration would be necessary to account for the extra air while resulting in a load value that is still sub 2.
 
Ok, lets see if I understand the following...

I logged the drive home and was playing with loading the engine up to see where I ended up for the overall load factor. In higher gears around 3000rpm, full throttle results in a peak of 1.93 engine load. There is one 1D table called "Requested Load Limit Overall" which I believe is the "global" load limit. I am inclined to up this to 2.5 from the value of 2 that it is at now.

The "Boost Limiter vs Atmospheric Pressure" 3D table topped out at 2.12 BAR. I am considering upping this to 2.45. The table does seem semi-confusing as it only goes up to 110kpa.

The "Desired Boost" Table does cap out at 2.12 BAR peak, which may indicate why I hit fuel cut if desired boost was set to the fuel cut limit. With fuel cut set at 2.45, my logic says I should be able to creep up the desired boost (balanced with increasing WGDC) to increase power. Additionally, is there any reasoning why peak boost appears to only be requested as high as 4000 RPM and tapers off from there? I.E. 2.12 bar at 4000 tapering down to 1.65 bar by 6500.

A disconcerting thing I noticed in the log is that under Open Loop WOT conditions, the ECU is requesting as rich as 9.4:1. This seems excessively rich even for a boosted engine. I am inclined to lean out the AFR table to about 11.3:1, maybe 11:1 depending on Knock count. (which currently I have only seen go as high as 2 once and occasionally over 1-1.5 during WOT pulls. This seems to correlate with the fuel dilution of engine oil causing ZZB as well.

The two "load by gear" tables do show the nerfing of 1st and 2nd, but their engine load values don't seem to correlate to what I see in my logs. I.e. gears 3-6 have a peak load value of 1.68 at 2500 tapering to 1.25 by 6500. My log easily shows engine load values above the table values such as 1.77 load at 4700rpm in 2nd vs the table max of 1.40 and 1.93 load at 2900 in 5th vs table value of 1.65.

Lastly, since I am apparently able to almost hit engine loading of 2, does this mean a MAF calibration adjustment is needed or can we push the load limit up a ways before a recal or larger MAF housing is needed?
 
Only do one form of control (load or boost) at a time. Trying to do both simultaneously will be a nightmare going forward. The reason why the map tapers off is because the K04 isn't efficient in the upper RPM ranges. Also yes, change your WOT AFR target to 11.4.

Raising the "global" load limit and then controlling the load by gear tables will be your best bet to start off. Don't go to 2.5 right away since you're already exceeding your load by gear targets though apparently. Increase it incrementally. Just keep boost control as it is currently. Make sure you're hitting your AFR targets and keeping knock under control before going too crazy.

You should also take the time to smooth out the weird cells that you've noticed too.
 
Last edited:
Shadowplane676 said:
I can see why it is a bit more clunky than VT or COBB as the UI is definitely not as refined. However in my case, it was way more cost effective. I have 3 vehicles that I can use ME on, 2 of which COBB doesn't support or no longer supports (2016 CX9 and 2005 RX8) and VT doesn't support the CX9 at last I checked. From what I can tell, all ME does is adjust the OEM table values rather than replacing the code entirely (a la COBB). I believe this is also how VT works. For what I am looking to accomplish, this should be more than sufficient for my platforms.
.
Click to expand...
I gotcha, using one dongle for all three makes a lot of financial sense. I think you can use that dongle with VT too, no? Not sure about it, but would be good. as I'm planning on going VT on the RX-8 down the road.
 
BAT-man said:
I gotcha, using one dongle for all three makes a lot of financial sense. I think you can use that dongle with VT too, no? Not sure about it, but would be good. as I'm planning on going VT on the RX-8 down the road.
Click to expand...

Yep, Tactrix 2.0 OpenPort cable. Can be used with Mazdaedit, VT, and a few other softwares like the free subaru/Mitsu ECUedit, Forscan and the like.

broda said:
Only do one form of control (load or boost) at a time. Trying to do both simultaneously will be a nightmare going forward. The reason why the map tapers off is because the K04 isn't efficient in the upper RPM ranges. Also yes, change your WOT AFR target to 11.4.

Raising the "global" load limit and then controlling the load by gear tables will be your best bet to start off. Don't go to 2.5 right away since you're already exceeding your load by gear targets though apparently. Increase it incrementally. Just keep boost control as it is currently. Make sure you're hitting your AFR targets and keeping knock under control before going too crazy.

You should also take the time to smooth out the weird cells that you've noticed too.
Click to expand...

Ok, I thought that might be the case, wasn't sure if it was the engine or the turbo that was dictating the max torque point.

Sounds like adjusting the current AFR targets and seeing what KR I get is probably step 1
 
Ok, made some updates on the ECU. One was targeting 11.3 under high load in the "Open Loop Fuel (Base)" map and in the "Closed Loop Fuel A" table. After logging the drive to work today, I am still seeing commanded AFRs down into the 9's. There are 3 additional Open Loop Fuel tables (Base, Knock, Overload and Unknown).

Unless I am missing something, I am guessing that I am not editing the correct table OR there is an additional corrections table that is negating my changes. Usually most cars go Open Loop when you go to WOT, so is the Speed3 different where it is in Closed Loop even under WOT? Even if it does, that table should also be targeting 11.3:1 AFR....
 
Whenever I've seen AFR tables the Normal and Overload have been identical. I'd also set the Unknown table the same as your Normal/Base one as well. And obviously set the Knock table richer. You'll know if you're in open loop because your LTFT and STFT will be zero'd out in your log.
 
You must log in or register to reply here.
Back
Top