What is AutoTune?

[Fastest95PGT]

You could set the auto-tune up to do something like this, which would work irrespective of whether you were running closed- or open-loop:

Code: Select all

[OutputChannels]
   ...
   lambda    = { 1.5 - 5.0 * egoADC/255.0               }
   afr       = { lambda * 14.7                          }
   targetAFR = { vexInterp(rpm, map, 0, "afrtable.vex") }
   AFRcorr   = { (afr / targetAFR) * 100.0              }
   ...

[AutoTune]
   table = veTableMap
      corrector = AFRcorr
      ...

Just make up a vex file "afrtable.vex" and you're off to the races.

Is that code put in the custom.ini?

Is the AFR Vex for use while in open loop because it wouldn't be reading the table? (or something?)

Is there a site that's explaining how this AutoTune works? I'm sure there's some 20 page thread somewhere, but one page that puts in the main points would be great if there is one.

[ochizon]

There are 2 functions for autotune?

1. Autotuning the VE table: Sets the VE output based on the wideband acheiving the desired output.

2 EGO correction: Once the VE table is set in stone, the wideband functions only for minute alterations to maintain the desired AFR output.

Well... Actually both simultaneously. Your MS will compute EGO correction and apply that internally. MT's auto-tune algorithm is watching that EGO correction and minimizing it by messing with the VE table. Obviously the MS does its EGO correction all the time (assuming closed loop is enabled), but MT can only do its bit when you have MT connected to a running engine.

Eric

So basically with the MT it sets a long term fuel trim, and the closed loop feekback sets short term fuel trims contiuously when not connected to MT. Got it! Thanks!

[efahl]

Is that code put in the custom.ini?

Yes, partly, it's an example, some of which already appears in the base ini file (the afr and lambda are defined in most code variants, you'll have to come up with your own vex file for AFR).

Is the AFR Vex for use while in open loop because it wouldn't be reading the table? (or something?)

No, that's just one way to use auto-tune without using the closed loop algorithms inside MS.

Is there a site that's explaining how this AutoTune works? I'm sure there's some 20 page thread somewhere, but one page that puts in the main points would be great if there is one.

I just added a list of links to this post, should get you to some my posts on how to use it and how to avoid its shortcomings.

http://www.msefi.com/viewtopic.php?p=71130#71130

Eric

[woh]

Eric

How about making this jump destination a sticky. I'll never find it again when I most needed.

[Fastest95PGT]

Thanks Eric, I think I understand your example now of the custom.ini code snippet. I'll have to look in to those threads you linked in the other thread more tomorrow.

[flyguyeddy]

along the same lines, can you set a specific afr target for ego correction at a certain map/prm? example: i would like to run lean at cruise, and i dont want closed loop to richen me up at certain parts in the ve table. can i tell it to work at certain values at vertain parts of the ve table?

[Fastest95PGT]

It is my understanding that if you're using a NB O2 then you shouldn't use the target AFR tables. So I don't think you can really target a leaner cruise AFR than the usual 14.7 and get good results.

[flyguyeddy]

well, what if you are running a wideband?

[Fastest95PGT]

Then you could set your lower MAP (cruising MAP area) to have a leaner target value then stoich.

[efahl]

along the same lines, can you set a specific afr target for ego correction at a certain map/prm?

Yes, if your wideband and firmware support it. Usiing my example above, you really only need a wideband, that would work with any firmware, so long as you can get the WB data signal into MT, you are all set.

Eric