Dumb Boost Targets Question

[NigeT]

Finally felt confident enough in my car to upgrade to firmware v1.4.1. I got the 33 warnings others have asked about - I am perplexed and confused by them. I used the TunerStudio firmware update utility but after the update I'm unsure whether to replace my existing (old) ms3.ini with the one in the 1.4.1 zip?


Nigel

[NigeT]

Attaching current tune.

[NigeT]

Interesting that the post firmware update load of the existing tune file appeared to create the Boost Control Bias Duty Table from the old Initial Values Table.

[nathaninwa]

You need to use the matching firmwares ini

[NigeT]

Thanks Nathan, I foolishly assumed that the TunerStudio firmware updater had handled what was needed since it loaded / updated the old tune.

[nathaninwa]

Im on the current beta in both cars, so I haven't used the uploader yet

[NigeT]

Before the update I did some logged boost runs and figured out rough values for boost duty for 3 of the 4 boost targets (not so easy with targets as % and MAP as absolute - have to remember to start logging before starting the engine...). I had set my initial values tables to these values (and interpolated the missing one) then did the update. The new bias table was set up with those values.

I noticed that my highest boost target was never being reached with the max duty in the tune. As I am unable to contact the tuner that mapped my car originally I decided it was safer to just lower the boost target to roughly what I was seeing actually be achieved, rather than leave it and increase the maximum duty (which does seem to lift the obtainable boost).

The update has changed the tune from "Advanced" to "Basically Mode". What do I now need to do to make sure that is working well and the tune is safe?

Thanks.

[nathaninwa]

I'd run boost in setup mode, you'll find that where the advanced/basic mode is. This run the bias table only based on target boost by allows you to tune the delta offset which will spool you faster. Rerun each target just to make sure the targets are flatlined then roll into basic mode to let day to day changes be handled by closed loop

[NigeT]

Thanks. I guess this would also let me confirm the bias values are right.
The delta must have been defaulted as part of the TS firmware update utility processing of the tune file, I think I remember you suggested a wide delta to start with?

[nathaninwa]

Yes. If the bias values are low and boost falls below the delta limit/boost target it ramps 100% duty back on causing oscillations. I've asked for setup mode to only use 100% on the initial hit and just follow bias table afterwards but users thought that was dunb

[NigeT]

How perfect do I need to get the duty bias values? Is it better for them to be slightly high or low?

The default delta seems to be 100 - is that a good starting point? It seems to give the feedback algorithm a lot of work to do.

Your suggestion makes sense to me.

My recent limited testing suggests my max duty is set to low. I also suspect from the duty values that my minimum duty is probably to low also, probably not been set at all. What is the safest approach for me to determine the true values for these settings?

I know that my boost targets have been set to not overstress the internals of my sick Mazda MX-5 NA 1.8 engine. I was wondering about just creating target tables with above 50% TPS populated with each target I bed and export then too file. Then load one, do a loved boost run, load the next, do a run etc. Does this risk overstating my engine for the highest targets which are only used in the normal tables to counter torque drop off at higher revs?

Thanks.


Nigel

[nathaninwa]

You know the boost limits the tuner set in place, so we can always go back to that

Reset the values to 0-100 for the tuning of the bias table

Delta of 100 would rely a lot on DC being close to even spool in time, so I'd make it around 50 for starters since we have a table that is close

Tune each boost target doing 3rd gear type dyno pulls and working each target level. I'm happy when I'm with in 5kpa plus/minus target but shoot for the touch lower side

Making the bias table as close as possible will make closed loop boost job easier in the end and PID tuning that much simpler

Once all of the boost bias table targets are tuned you'll see the new Lower and upper valve limits that you can set to with a little wiggle room each way

Do you run different targets per gear or a blanket X KPA for all gears?

[NigeT]

Thanks Nathan.

I don't think my 1998 mk1 / NA MX-5 (Miata) had the tech in it to be able to derive the gear ratio. Not even the most basic ABS and the speedometer is mechanically driven. So it is blanket boost.

Do you think I should limit my two higher boost targets (175 and 180 now) to the higher rev range for their bias running runs?

[NigeT]

Is there any general rule or guideline for how boost control duty varies with throttle position for achieving the same boost target? I'm guessing 50% throttle might need considerably more duty cycle than 100%?

[NigeT]

I started trying to tune my Boost Duty Bias Table today. Not terribly successful for two reasons:

1. Not feeling terribly with it and forgot to switch from Basic to Setup Mode until the last couple of boost runs.
2. Having checked the log I appear to have been running with Boost Target Table 2 active without knowing it (switch set for Boost Target Table).

Anyway it looks like 60% duty is giving me an average of about 185% boost (I'm calculating this as (MAP / (average engine off MAP)) * 100) based on the last couple of pulls (the ones actually in Setup Mode).

In Basic Mode I experienced over boost fuel cut several times on partial throttle. I wasn't really expecting that, so I lowered the Duty Bias to 30 for the 140% target. Of course then the boost runs that I was expecting to be at the 140% target were not. Interestingly I just noticed that when I wasn't in Setup Mode my maximum boost target, even on wide open throttle, was 140%. It was only after switching to Setup Mode that I saw boost targets of 160, 175 and 180% (from Table 2).

Should I be calculating a boost % as I described above to compare the value achieved with the boost target (which is I believe a percentage)? Or should I just pretend that the MAP absolute value is a percentage so can be directly compared? The MAP average for the steady 60% duty periods was approximately 181 kPa.

I would have attached the log but even zipped it is too big.

Thanks.

[NigeT]

Just a note to self really - Boost Targets are absolute kPa not percentages. I'm not sure where I picked up that idea from.

This means my estimated boost bias values seem to actually be pretty close and I'm getting loads of instances of overboost fuel cut in Basic Mode.

[NigeT]

Saw a strange thing in a log - duty cycle dropping to 0 but I can't see why. Any ideas?

[nathaninwa]

You need to post a bit more of the log. Some before and some after. All the info in jumbled behind the min/max numbers in mlv

But from what I see there isn't a problem. Duty stays 44% until you lift. You did overboost. Do you have a target of 160 with overboost set at 170?

Post longer log and your msq

[NigeT]

Thanks Nathan, the log is quite huge (40+ minutes) so I was trying to make it more specific. Target would be max 160 on that table and I have tolerance at 10. Why did I miss the overboost - it was the first thing I looked for? I'll post more log and msq tonight. Thanks.

[NigeT]

Bigger subset of the log and what I believe is the matching .msq. It looks like I had boost in Basic Mode by mistake which would, in my current experience, lead to much overboost fuel cut, but in this case it hasn't (quite) reached 10kPa over target.
Thanks.