Curious on the factory boost control strategy....

[PowerPerLiter]

Is there a hierarchy or can someone elaborate for me the strategy for the ecu to adjust the boost level to maintain targets. Example: does the bov vent first after the wastegate gets adjusted and then timing? Does the car adjust intake or exhaust valve overlap during certain conditions to "bleed off cylinder pressure". Is there a good technical response or do we know fully? From my understanding all the electronic control of the wastegate/recirc valve/ throttle blade are all real time and adjusts incrementally at a fairly constant rate to stay at certain boost targets.

In any of the aftermarket tunes is valve overlap manipulated to induce quicker spool time or increase top end?

Does the honda factory calibrations use valve overlap to help keep the intake valves clean as apart of their strategy to combat carbon buildup at light cruise (say during emissions system checking at low load)? Do the stage tunes change this?

Thank you in advance.

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[KTuner]

Is there a hierarchy or can someone elaborate for me the strategy for the ecu to adjust the boost level to maintain targets. Example: does the bov vent first after the wastegate gets adjusted and then timing? Does the car adjust intake or exhaust valve overlap during certain conditions to "bleed off cylinder pressure". Is there a good technical response or do we know fully? From my understanding all the electronic control of the wastegate/recirc valve/ throttle blade are all real time and adjusts incrementally at a fairly constant rate to stay at certain boost targets.

In any of the aftermarket tunes is valve overlap manipulated to induce quicker spool time or increase top end?

Does the honda factory calibrations use valve overlap to help keep the intake valves clean as apart of their strategy to combat carbon buildup at light cruise (say during emissions system checking at low load)? Do the stage tunes change this?

Thank you in advance.

It is a closed loop strategy and multiple things occur to spool, reach, and maintain target. Not only can you feel what's going on, but it becomes pretty evident in the data you can see during datalogging.

We change nothing as far as Honda's controls intent on cleaning etc. The one thing that does majorly change with the tunes is that we don't run lean at wide open throttle like factory does, since we're at much higher boost levels than factory intended. Running 14+ AFRs at 21PSI simply because Honda saw fit to do so at 12PSI is not an acceptable tuning practice in our books.

 

[PowerPerLiter]

Thank You for the response! So nice to get some facts on things.

I agree about the afr target completely. Does your software implement the use of manifold pressure to switch to open loop sooner or is the change in afr derived purely from afr target and maf scale differences (not trying to decode your methods just wondering whats better for the car.... to stay using maf signal or switch to map signal to reference wot)

 

[KTuner]

The MAF curve is used to achieve a perfect stoichiometric AFR given the amount of flow registered. The closed loop targets and WOT Enrichment Target AFR table then depicts the actual target AFR by increasing fuel by a percentage, but we depict this as AFR to make it easier in the software. We actually choose to run closed loop more than factory does, even at wide open throttle in some circumstances, because of the sheer neglect of the industry leading companies that create intakes for these without properly designing the MAF housings to be used without additional tuning. Closed loop can actually help prevent codes and overly lean/rich situations from coming up.

It is a catch-22 situation, though, as it's not a perfect system. While on the non-Si a certain brand intake may be 7-10% off on the housing, which the ECU is able to catch and assist with on KTuner because we utilize closed loop much more, that same brand on the Si is off up to 30%, which the ECU can't quite compensate for all of the time even with closed loop active. It wouldn't be hard to guess which brand that is.

BTW you can watch the AFR Target / Actual AFR and Short Term/Long Term fuel trim relationship in logging.

 

[PowerPerLiter]

The MAF curve is used to achieve a perfect stoichiometric AFR given the amount of flow registered. The closed loop targets and WOT Enrichment Target AFR table then depicts the actual target AFR by increasing fuel by a percentage, but we depict this as AFR to make it easier in the software. We actually choose to run closed loop more than factory does, even at wide open throttle in some circumstances, because of the sheer neglect of the industry leading companies that create intakes for these without properly designing the MAF housings to be used without additional tuning. Closed loop can actually help prevent codes and overly lean/rich situations from coming up.

It is a catch-22 situation, though, as it's not a perfect system. While on the non-Si a certain brand intake may be 7-10% off on the housing, which the ECU is able to catch and assist with on KTuner because we utilize closed loop much more, that same brand on the Si is off up to 30%, which the ECU can't quite compensate for all of the time even with closed loop active. It wouldn't be hard to guess which brand that is.

BTW you can watch the AFR Target / Actual AFR and Short Term/Long Term fuel trim relationship in logging.

Holy hell in a hand basket!!! Thank you!... even if it's just information this is the kind of stuff I need. Intelligible interaction!!! Seriously just for this im going to buy your product and see what I can do with it. No bull. Your winning a customer.

 

[KTuner]

The drivability is completely different (and adjustable on multiple levels). If you do give us a shot I'd definitely be curious if you decide to stick with us after the experience.

 

[PowerPerLiter]

I'll keep you posted as soon as I order. Im signing on a new home currently but as soon as this calms down I'll be ordering. Would you suggest the lcd with or no? Will I be able to use my phone as display like now or do you think the will come a time when 2018s are supported to the head unit? (ultimate goal)

 

[KTuner]

Will I be able to use my phone as display like now or do you think the will come a time when 2018s are supported to the head unit? (ultimate goal)

I certainly think there will come a time when it works (Like tomorrow perhaps), but you can still use a phone if you want!

 

[Toolz]

The MAF curve is used to achieve a perfect stoichiometric AFR given the amount of flow registered. The closed loop targets and WOT Enrichment Target AFR table then depicts the actual target AFR by increasing fuel by a percentage, but we depict this as AFR to make it easier in the software. We actually choose to run closed loop more than factory does, even at wide open throttle in some circumstances, because of the sheer neglect of the industry leading companies that create intakes for these without properly designing the MAF housings to be used without additional tuning. Closed loop can actually help prevent codes and overly lean/rich situations from coming up.

It is a catch-22 situation, though, as it's not a perfect system. While on the non-Si a certain brand intake may be 7-10% off on the housing, which the ECU is able to catch and assist with on KTuner because we utilize closed loop much more, that same brand on the Si is off up to 30%, which the ECU can't quite compensate for all of the time even with closed loop active. It wouldn't be hard to guess which brand that is.

BTW you can watch the AFR Target / Actual AFR and Short Term/Long Term fuel trim relationship in logging.

Great info thank you, very satisfied v1.2 customer!
Regarding the STFT and LTFT, when datalogging and watching it live, what range would you consider acceptable?Thx!

 

[KTuner]

It will definitely vary based on the situation, but if you want to keep long term trims as closed to 0 as possible. That's not saying that the sways in short term aren't important, but long term is the trend, generally. We've seen stock sway short term quite far for correction, even. That is NOT the tune.

 

[PowerPerLiter]

Since this is getting so much valuable info. I'll ask this without creating another thread. If the target boost command does not match the actual boost pressure or map pressure is this the turbo being maxed out? Im referring to high rpm. I have a hard time allowing my target boost command curve tapering to 1.8 bar from 2.58 not even 1300 rpm before. But if the turbo is maxed it's maxed. I just wonder if the ecu is doing something I don't know about to keep a taper without me knowing.

Can these turbos create a legitimate (albeit warmer) 21-23 psi until 6400 or is that asking too much?

 

[KTuner]

Commanding too much will show IATs climbing pretty quickly, generally. At that point you're just blowing inefficient hot air.

If the target is still set higher and you don't see the wastegate position closing in logging that's a pretty good indicator that it's just not able to hold. On the Si it liked to taper down on the top end or it lost power pretty severely.

 

[PowerPerLiter]

Yeah I noticed that on the log files with my custom boost maps which did have taper in the calibration from 23 psi down to 21 from 4700-6000+ but it still didnt match target and was down to 17psi by redline...I ll have to review it again and watch the wastegate command and duty cycle. what I did instead thus far is take the pressure ratio target to just under what the turbo seemed to "want" to output and increase timing cells up top by .95 degrees.

MBT seems to be ~ 0 -5 degrees at peak torque is that a solid assumption?

 

[KTuner]

Are you by chance not at sea level?

 

[PowerPerLiter]

I am not. Anywhere from 500-1k ft. above during my commuting locally.

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