Dumb Boost Targets Question

[NigeT]

Is it OK to do the wot pulls in 2nd year? I'll have to find a quiet stretch of road to do them as the track to my house is too bumpy and too short between blind bands. I still cannot work out what wideband is least flawed. I would get the AEM X series inline controller with the Bosch sensor, but that has no gauge option currently. The AFR500V2 seems to come from a series of controllers that don't get criticism and get a lot of praise, and the NTK sensors seem to be considered more robust. More expensive but if it doesn't break them maybe with it.
Thanks for any advice.


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[benckj]

Reading through your thread as I am looking into MS boost control on my 3sgte. I'm still running a separate EBC system until I get my car tuned correctly. Just don't need another variable now.

Most of the cars & Tuners I know of run the Innovate O2's and Bosch LSU 4.2 sensor due to stable and reliable operation under all sorts of fuel conditions. I bought the MTX model including gauge & sensor for $132USD from an ebay site with free shipping. Might be worth a look.

Keep the thread going with updates.

Jim

[NigeT]

I of course meant can I do the 2000-7000 rpm (rev limit) pull in second gear (I've switched to an iPad and am having a real fight with the horrid touchscreen and keyboard apps - I'm surprised I've not launched it into the field yet).
Is there a way to figure out the minimum and maximum duty of the boost control valve that my tuner fitted (he replaced the one supplied by MS-Labs that I had fitted).
I am probably going to go with an X series AEM wideband controller with the MS-LABS CAN module so I can use the digital output from the controller for the MS3. I have spent many hours researching wideband controllers and sensors with Google and Innovate have very mixed feedback about reliability, but then so do almost all of the manufacturers at the budget end of the market. If I wasn't looking at the digital output I'd probably lean towards the AFR500V2 or NTK or 14point7 controllers, the former with the calibration grade NTK sensor.


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[nathaninwa]

Second gear just won't provide the load to get accurate tuning done

I'm a huge fan of Aem widebands. 4 of my projects run them and any install I do gets one

[NigeT]

Thanks Nathan, I'll have to find a private road or something I guess.

[nathaninwa]

To give you an idea, my car, which weighs 3700lbs has a very built 2jz with an efficient precision 64mm turbo. The duty cycle that will net me 32psi by 4300rpm, only produces 18psi near redline in first and 23psi near redline second, but will spool and make all sorts of power in third and flatline boost for about 2500 rpm

[NigeT]

I'm looking for much less on my stock internals 1.8 MX-5 (Miata) with GT2560R with FM manifold, elbow and downpipe, 200 cell cat and 2.5" system. It has Fab9 COPs and RX-7 yellow injectors (tested and cleaned). I guess it weighs around 1000kg. Because of the stock internals boost is limited to limit torque to around 200 left (201 on the hub dyno chart) on the higher boost and higher advance settings ( I have switchable boost and ignition tables for different conditions and fuel quality - for the latter I prefer Shell 98 but have the other setting for other super unleaded fuel).
Does any of that make any difference?


Nigel

[NigeT]

Is the Maximum Duty setting a function of the solenoid valve, the wastegate actuator or the whole system? Trying to understand why it is set to 60. Valve is a Pierburg 7.01024.02.0, actuator the standard unit on a Garret GT2560R. Thanks.


Nigel

[nathaninwa]

Maybe somewhere Along the way it was changed and stuck in your tunes. Typical range is 10 to 90% on a boost valve. I'd raise it if 60% isn't reaching your max target. Iirc the code will still use 100% till the delta at which point any limits will be applied

[NigeT]

Daniel Elias (Ardler Automotive) tuned the car on the dyno. He changed the boost control solenoid valve from what MS-Labs supplied with the Megasquirt and changed Solenoid Frequency, Control Interval, Maximum Duty and Algorithm (and the PID settings) from what was in the base map that was supplied. Unfortunately I have no idea why he picked the values.
The higher boost target table has maximum of 185 in it, but that is not directly related. I guess I need to look at the Initial Duty tables - these only have values greater than 60 for rows (boost_target_1/2 %) of 220, 240 and 260. I would think these rows are superfluous for my setup given my max target of 185, no? Having said that target of 185 would call for an initial duty between 60 (from the 180 row) and 70 (from the 220 row), which would be above the Maximum Duty(%) setting, assuming that these duty percentages are absolute and not a percentage of the range between Minimum Duty(%) and Maximum Duty(%).
Out of curiosity is the "boost_target_1/2 %" legend correct, are these percentages of some boost target value? Or is it the help for the Boost Control Target tables that us wrong, saying "For closed-loop boost, sets the target kPa (boost) vs. TPS/RPM. Should it say "sets the target percentage (of barometric) vs..."
Thanks for your help and patience.


Nigel

[nathaninwa]

Back when I was on 1.3.x firmware I too limited the valves upper range to keep oscialtions down when tuning the pid stuff

[NigeT]

Thanks Nathan, is, that something you left permanently in place, or only used while getting the PID parameters honed? Would you expect it to be left set that way, especially when the tune calls for a (albeit slightly) higher value.

[nathaninwa]

I always left it at the lower setting. I remember now tuning the open limit so it would hurt spool. Maybe you only needed 60 on the dyno, but on the street you need more

[NigeT]

Again thanks. Does all this become irrelevant if I update to 1.4.1? Is the way to determine true minimum and maximum values to do boost runs at the different duty percentages and review the boost levels achieved with each?

[nathaninwa]

I'd make it 90 to 100%. Once the bias table of tuned the code is always using that as an initial lookup for the next rpm level and closed loop is only making minor adjustments. Where as before it was working overtime based on the first initial value

[NigeT]

Is there a way to derive the bias tables from my existing Boost Control Initial Duty Tables? At least to get a start point to work from. My boost target tables seem to be quite simple, the lower boost table had the same target across all rpm buckets, the other has a lift above 5000rpm to counter the natural torque drop off. I understand that there is a deliberate restriction on the boost targets to keep the torque down to protect the engine.
I don't really understand how the Initial Duty tables work. Imagine a boost pull from 2000-7000rpm. I have rpm "buckets" every 1000 rpm starting from 1500, which of the Initial Duty values will get used? Just some interpolated value between the 1500 and 2500 "bucket" values?


Nigel

[nathaninwa]

I'm bbq'ing right now. I post my 2j tune for you to look over.

You don't need bins below like 2500 unless you spool incredibly quick

But yes, your initial values can get started in the right direction

[NigeT]

Bbq sounds good - you really shouldn't be answering my dumb questions. Enjoy. No rush on the tune or anything, it will be some time before the new wideband setup arrives and I can get it fitted so I am just trying to learn in preparation. Thanks so much for your help.


Nigel

[NigeT]

Perhaps naively I simply switched Boost Control Enabled to Off, to disable boost control, but with it set this way the engine will not start. At start the boost is non existent and controlled by the actuator spring, anyway, so why would the engine not start? Confused.

[NigeT]

Thanks to some extreme support from Reverant my car seems to be working a bit more normally again. I did a WOT almost to the red line pull, uphill in 3rd gear with boost controlled by the actuator spring. Here's a link to the log.
https://www.dropbox.com/s/duzqhs4f6x179 ... 1.msl?dl=0