ECUTEK Closed Loop question

[Tatsu333]

I've read a couple of places that some ECUTEK tunes are running closed loop full-time, but according to the ECUTEK ProECU Tuning Guide (https://ecutek.atlassian.net/wiki/sp...U+Tuning+Guide), the AFR targets for closed loop can't be changed from 14.7:1.

Is the guide incorrect, and these target AFRs can now be changed for full-time closed loop, or am I missing something (some new/different maps not covered in the guide)?

[Tatsu333]

For further detail, this is what the tuning guide says:

Open and Closed Loop Control

Closed Loop is when the ECU is using the feedback control of the lambda sensors to maintain a steady 14.7:1 AFR (or Lambda 1). This closed loop target value cannot be altered from 14.7:1. The front ‘widerange’ AF sensor #1 is located before the Catalysers and allows the ECU to ‘adjust or trim’ the Fuel Injection volume amount very accurately so as to achieve the target AFR. This Fuel Trim can be seen under LIVE DATA as Fuel Trim Short Term and Fuel Trim Long Term. Closed Loop condition will be seen below 4000rpm and at light load conditions.

Open Loop is when the ECU is no longer using the feedback control of the lambda sensors to maintain a specific AFR but it will simply take an AFR value from the fuel map. This open loop AFR value will normally be lower (or richer) than 14.7:1 and as low as 10.5:1 depending on the exact model. The front ‘widerange’ AF sensor #1 can read to 12.2:1 AFR but has to be rescaled to read past 12.2AFR or 0.82Lambda, the accuracy is limited at richer AFR and it should not be completely trusted.

My interpretation from this is that it is only learning the short-term and long-term trims in closed loop vs stoichiometric (14.7:1), and that in open loop it will apply any previously-learned long-term trims + whatever the calculated difference is in target AFR vs. stoichiometric to achieve the target AFR.

It looks like there is really only one "Fuel Map" per mode, with closed loop ignoring the target AFR's in that map and only targeting stoichiometric (not the map's target AFR values, which are used for open loop). Not sure if this is correct? Does "full time closed loop" (if that option actually exists) make it that it will use the actual fuel map values as targets?

I'm trying to wrap my head around how it's going to accurately learn a value / trims for stoichiometric at higher-load conditions if it's not operating in closed-loop under those conditions, never mind the fact that it would be potentially dangerous to the motor to run that lean at high load.

Maybe I'm just over-thinking this, coming from tuning a standalone Hydra EMS from scratch on my last car (without a workable base map - that was interesting, to say the least)? On that unit, the base fuel map values were injector opening times in milliseconds, and then I used closed-loop control with target AFR's to tune it over time (using the system's autotune feature to learn / apply LTFT's) and adjust those base map values accordingly until my trims were in a reasonable range.

In this case, I'll be starting with a known-good (in terms of base values vs. AFR targets) factory ECU ROM, so if I don't mess with the injector maps, it *should* scale the values correctly with any changes in open loop target AFR's I set when tuning. In theory, easy-peasy.

But what if, for example, I discover from logging that the stock map ISN'T actually hitting the AFR targets at high loads. E.G. I want the actual AFR to be 12.5:1 and it's actually at 11.5:1. How do I then fix that?

Do I set a "wrong" value in the Fuel Map target AFR's for it to then calculate the desired "right" value?

Do I directly edit the Long Term Trims to hit the target correctly (which then would only remain unchanged if I didn't end up in closed loop at that target load / rpm)? Can I even access / edit the Long Term Trims?

I have to say, while I'm looking forward to tuning from a known-good base map (the factory ROM) so I don't have to mess around with a lot of the idle control, temperature compensations, etc. that affect the daily drivability (which was the biggest frustration for me tuning my previous car on the standalone, and took literally years of tweaking to really dial in), the control freak in me wants to be able to see every parameter, even if I can't do anything about some of them!

[steve99]

OK

in the normal operation assuming you dont have ecutek closed loop mode active

low throttle and cruise you generally in subaru closed loop mode

AFR is target is set by the Closed loop AFR tables, standard these are close to 14.7 but can be changed. The ECU will not target AFR leaner than 14.7 even if you set leaner targets, is always best to target just rucher than 14.7 ie 14.69 in those tables or richer. You can get some weird effects if you target 14.7 or leaner.

In subaru closed loop the ecu will attempt to track the target afr as best it can , but it is dependant on maf scaling injector scaling being correct and that your not targeting an afr outside the calibration range of the front 02 sensor scaling stock its 12.17 afr max rich but can be rescaled down to round 10 afr successfully.

Fuel trims are only learned in subaru closed loop mode

The last learned LTFT in highest air flow band will be applied to open loop mode



During heavy throttle or higher rpm you will transition to subaru open loop mode

Primary open loop fuel target table now used

Defendant on maf scaling injector scaling. The ecu just injects amount of fuel it calculates, there is no feedback control in open loop 02 sensor not used

The ecu doesnt try to track afr, but you can see rersult my looking at 02 sensor afr assuming your not targeting an afr richer than the 02 sensor is scaled to read.



Ecutek closed loop mode

This mode will overide subaru open loop mode and work togeather with subaru closed loop mode.

This can cause a bit of an issue if you set ecutek closed loop mode to come in at low rpm and low engine load, you can get ecutek closed loop and subaru closed loop fighting each other and get weird high fuel trims.

best to not activate Ecutek closed loop below about 3000 rpm or below about 0.7 engine load

Note ecutek closed loop mode uses the subaru OPEN loop target tables not the subaru closed loop target tables.

you also need to be sure the 02 sensor is rescaled so it can read the richest afr in the subaru open loop tables or ecutek closed loop will not work correctly as it wont know the afr for feedback correction.

you can also get weird effects of ecutek closed loop and subaru closed loop fight each other at low rpm and throttle due your settings.

you can also get strange effects if the ecu transitions from subaru closed loop, then subaru open loop before it gets to ecutek closed loop.

Dont rely on ecutek closed loop to solve bad maf scaling or injector scaling issues or poor Speed density VE table settings, you need to get those pretty close and just use ecutek closed loop to correct the final few percent.

[Tatsu333]

Thanks for all that info!

My plan is to stay NA, with all the factory sensors (O2, MAF and MAP) and stock injectors in place, so MAF scaling, injector scaling and rescaling the O2 sensor/AFR should all not be necessary.

With all that in mind, I have a few questions regarding the info you provided:

Originally Posted by steve99

AFR is target is set by the Closed loop AFR tables, standard these are close to 14.7 but can be changed

Are both the closed loop and open loop tables editable with ECUTEK?

The tuning guide only seems to refer to one "Fuel Map" per mode. If only one is editable in ECUTEK, then I'm guessing that is what you refer to as the "Subaru Open Loop" table - is that correct?

Originally Posted by steve99

The ECU will not target AFR leaner than 14.7 even if you set leaner targets, is always best to target just rucher than 14.7 ie 14.69 in those tables or richer.

The tuning guide says "Closed Loop is when the ECU is using the feedback control of the lambda sensors to maintain a steady 14.7:1 AFR (or Lambda 1). This closed loop target value cannot be altered from 14.7:1." I'm guessing again that maybe they say this because what you refer to as the "Subaru Closed Loop" table isn't editable in ECUTEK?

Originally Posted by steve99

Fuel trims are only learned in subaru closed loop mode"

Originally Posted by steve99

Ecutek closed loop mode

This mode will overide subaru closed loop mode and work togeather with subaru closed loop mode.

Originally Posted by steve99

Note ecutek closed loop mode uses the subaru OPEN loop target tables not the subaru closed loop target tables.

How do you determine which closed loop mode you are using?

Are the "Open Loop Throttle Threshold Manual" and "Open Loop Per Gear RPM Thresholds Auto/Manual" controls for invoking open loop operation listed in the tuning guide switching from "Subaru Closed Loop" or "ECUTEK Closed Loop", or overriding ALL closed loop operation?


Thanks again for your input - I really appreciate it!

[steve99]

Originally Posted by Tatsu333

Thanks for all that info!

My plan is to stay NA, with all the factory sensors (O2, MAF and MAP) and stock injectors in place, so MAF scaling, injector scaling and rescaling the O2 sensor/AFR should all not be necessary.

You will generally want to go as rich as 11.7 or so even NA so you will need to rescale 02 sensor to richer than the stock 12.17 scaling or you cannot use ecutek closed loop mode

With all that in mind, I have a few questions regarding the info you provided:



Are both the closed loop and open loop tables editable with ECUTEK?

Yes both open loop and closed loop tables can be edited in ecutek

The tuning guide only seems to refer to one "Fuel Map" per mode. If only one is editable in ECUTEK, then I'm guessing that is what you refer to as the "Subaru Open Loop" table - is that correct?

If you have ecutek racerom extension pack you can see and edit all four map modes if not your restricted to map 1 mode only.

Fuel map mode 1,2,3,4 are the subaru open loop fuel maps but ecutek closed loop will use these subaru open loop maps as the ecutek closed loop target maps. The maps are used on modes 1,2,3,4 if you have a four mode tune and are separate for each mode.

Closed loop AFR adjustment maps 1 and 2 are the subaru closed loop target tables they are common to all map modes, but keep both those same if you change them





The tuning guide says "Closed Loop is when the ECU is using the feedback control of the lambda sensors to maintain a steady 14.7:1 AFR (or Lambda 1). This closed loop target value cannot be altered from 14.7:1." I'm guessing again that maybe they say this because what you refer to as the "Subaru Closed Loop" table isn't editable in ECUTEK?

Not sure why they say that as you can alter the subaru closed loop tables to target richer than 14.7 i use them down to 11






How do you determine which closed loop mode you are using?

Are the "Open Loop Throttle Threshold Manual" and "Open Loop Per Gear RPM Thresholds Auto/Manual" controls for invoking open loop operation listed in the tuning guide switching from "Subaru Closed Loop" or "ECUTEK Closed Loop", or overriding ALL closed loop operation?

Subaru closed loop to open loop switching is determined by a bunch of tables
under the "open loop" folder in ecutek


Ecutek closed loop mode is determined by the tables in racerom section under ecutek closed loop fueling folder



when im saying subaru mode i mean how the ecu functions normally without ecutek racrom patch added or used


Thanks again for your input - I really appreciate it!

Note if you have not purchased the racerom extension pack from your tuner you cannot access modes 2,3,4 or the advanced racerom fesatures like ecutel closed loop , flex fuel speed density as seen in the instruction manuals

[tomm.brz]

and you can t access the engine load limiter table, and that could be a problem if your setup will go over 1.3 ( you could trick things to avoid the leanness it would cause if you are skilled, but wont suggest that... also you can t fine tune the load limiter on the shitty zone 1600-3000 rpm)

Racerom self tuner upgrade is a must if you plan to totally retune by your self

Also the closed loop fuel control during full WOT open loop can be evil, when you rescale perfectly the maf/SD, it tends to remove a bit of fuel when you are on taller gears, due to be much more progressively slower to reach redline (a. k. a taller gears become effectively richer than the previous smaller gear... so the closed loop fuel control will remove fuel to reach the target) So when you activate it, it d be better to implement a per-gear timing compensation if you are on the verge on knock like you are supposed to be if you want maximum power and efficiency... or even a per-gear enrichment compensation using the custom maps

[Tatsu333]

Originally Posted by steve99

when im saying subaru mode i mean how the ecu functions normally without ecutek racrom patch added or used

Thanks again for all the info, and for that clarification - very helpful!

So - "Subaru Closed Loop" is the regular closed-loop functionality, "ECUTEK Closed Loop" is what is enabled using the "Closed Loop Fueling" options under RaceROM.

Originally Posted by tomm.brz

and you can t access the engine load limiter table, and that could be a problem if your setup will go over 1.3 ( you could trick things to avoid the leanness it would cause if you are skilled, but wont suggest that... also you can t fine tune the load limiter on the shitty zone 1600-3000 rpm)

Racerom self tuner upgrade is a must if you plan to totally retune by your self

Also the closed loop fuel control during full WOT open loop can be evil, when you rescale perfectly the maf/SD, it tends to remove a bit of fuel when you are on taller gears, due to be much more progressively slower to reach redline (a. k. a taller gears become effectively richer than the previous smaller gear... so the closed loop fuel control will remove fuel to reach the target) So when you activate it, it d be better to implement a per-gear timing compensation if you are on the verge on knock like you are supposed to be if you want maximum power and efficiency... or even a per-gear enrichment compensation using the custom maps

Thanks to you as well!

I'm planning to get the RaceROM BRZ upgrade for sure, as I believe the 4-way map switching will be useful for me in back-to-back testing and logging of small tweaks as I develop my tune.

From what I understand, I don't think I'll see loads over 1.3 running NA, but good to know that anyway.

Not sure yet whether I'm going to use Speed Density tuning or stick with MAF tuning (or a hybrid), or whether I'm going to use WOT closed loop. I'll definitely bear in mind your advice about the per-gear compensation if I go that route!

[steve99]

[QUOTE=Tatsu333;3506396]Thanks again for all the info, and for that clarification - very helpful!

So - "Subaru Closed Loop" is the regular closed-loop functionality, "ECUTEK Closed Loop" is what is enabled using the "Closed Loop Fueling" options under RaceROM.


Yes thats correct