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ISCV control system disassembly

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Old Feb 14, 2019, 11:01 PM
  #406  
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Originally Posted by chamelieon
Hey guys bringing this back, I have collected every known iACV table in the universe from left to right messed with every single one and not one will do what im after, so im under the belief im doing something wrong or just still missing a certain table, so problem is in neutral or clutch in decel, rpms will drop down to 500-700 and then come up, i would like to believe that if 25 steps will hold 1000rpm idle then as soon as the engine revs over 2k it would step to 30 or 35 so when the rpm comes down it will fall to 1200-1500 and then decay down to 1000rpm. IPW turns back on at 2k but idle steps wont budge from whatever is the base setting for idle.

i need a solution to this asap and will compensate anyone willing to help or has the proper XML code that im missing, possibly even the "DECEL fuel resume rpm" tables for 8859 and 9417 roms!

Did you try to adjust BISS and then fiddle with steps ?
Old Feb 14, 2019, 11:44 PM
  #407  
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What's the advantage of setting the BISS according to steps as opposed to adjusting until the trim is at zero?
Old Feb 15, 2019, 08:49 AM
  #408  
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if anyone needs the "Decel Fuel Resume RPM" for 8859 here it is. solved my decel issue.

<table name="Decel Fuel Cut Resume RPM" category="Fuel" address="3030" type="2D" scaling="RPM8">
<table name="Engine Temp" address="6fde" type="X Axis" elements="8" scaling="Temp" />
</table>
<scaling name="RPM8" units="RPM" toexpr="x*125/16" frexpr="x*16/125" format="%.0f" min="0" max="2000" inc="50" storagetype="uint8" endian="big" />
Old Feb 16, 2019, 07:42 PM
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Interesting. What does that table do? Do you have the defenition for 9417?
Old Feb 17, 2019, 09:30 PM
  #410  
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Originally Posted by kaj
What's the advantage of setting the BISS according to steps as opposed to adjusting until the trim is at zero?
Hey Kaj,

In my experience, Trims wont ever settle down. Using BISS i acheived very stable idle.
Old Feb 17, 2019, 09:58 PM
  #411  
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Originally Posted by mines5
Hey Kaj,

In my experience, Trims wont ever settle down. Using BISS i acheived very stable idle.
Thank you! Mine fluctuates, when the cool.down fan comes on (seems like steps would also), but it zeros out once it goes off.
Hmm.
I guess there's more than one way to skin a cat.
Old Feb 20, 2019, 01:21 AM
  #412  
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Originally Posted by kaj
What's the advantage of setting the BISS according to steps as opposed to adjusting until the trim is at zero?
Originally Posted by mines5
Hey Kaj,

In my experience, Trims wont ever settle down. Using BISS i acheived very stable idle.
Having tuned 100s of evos and having done setting the BISS many ways,(the service manual way, the forum way, and zero trim way) I can say without a doubt, the zero trim way is the best.

You do get those fluctuations with any way. Their just a by product of the voltage change.

When you do the trim way, you do use the BISS, so dont know what your saying there.

Also the trims settle down. My have stayed between 0 and +1 for years.

Last edited by Evo_Jay; Feb 20, 2019 at 01:27 AM.
Old Feb 20, 2019, 01:24 AM
  #413  
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Also, as per MRFRED disassembly, the unit of "steps" is incorrect. That was an error done in early development. The way the ECU thinks of it is a demand %.

And looking/tuning at the ROM in steps vs demand is no different. Your looking at the same hex data, just one of them has incorrect scaling and is reading wrong.
Old Feb 20, 2019, 07:47 AM
  #414  
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What do you mean by 0 trim way? Not sure if I ever heard of setting it that way. Can you explain?
Old Feb 20, 2019, 07:49 AM
  #415  
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If I'm not mistaken it's like tuning fuel trims, you adjust the biss to get as close to 0% as you can.
Old Feb 20, 2019, 08:42 AM
  #416  
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Close to 0 steps or 0 demand? I tried tuning for 0 demand adjusting boss according to % and it would always jump down or up. Would never stay close to 0.
Old Feb 20, 2019, 09:10 AM
  #417  
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Originally Posted by nor11384
Close to 0 steps or 0 demand? I tried tuning for 0 demand adjusting boss according to % and it would always jump down or up. Would never stay close to 0.
0 trim not 0 demand.
Old Feb 20, 2019, 09:19 AM
  #418  
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0 trim? **** is that even possible? Looks like I have some studying to do. Do you do this by altering steps table or messing with biss until trims are close to 0?
Old Feb 20, 2019, 09:22 AM
  #419  
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Originally Posted by nor11384
0 trim? **** is that even possible? Looks like I have some studying to do.
well its a representation of what the ecu has learned it has to do to reach its targets, 0 means your tune is so on point the ecu doesn't have to do anything. 0 probably wont happen because static settings can't work for all situations, but the closer to 0 you get the better.


P.S. in this context the biss position would also be part of the "tune". To make a bad analogy, kinda like fuel pressure would effect the injector tune.

Last edited by Biggiesacks; Feb 20, 2019 at 09:34 AM.
Old Feb 20, 2019, 11:07 AM
  #420  
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Not a bad analogy...makes sense. Reason I ask is because I know some people alter the steps table. I was wondering if that was what you guys mess with in this process other than biss.


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