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Should we be disabling closed loop when tuning AFM like older vehicles?

Posted: Wed Sep 11, 2019 6:42 am
by gtfrede07
If so by what method? I was under the impression the limits we have available are just the max values before a check engine light occurs. My memory tells me there isnt a disable closed loop check box.

Re: Should we be disabling closed loop when tuning AFM like older vehicles?

Posted: Wed Sep 11, 2019 8:22 am
by gtfrede07
I have had a lot of success without doing this anyway.....

Re: Should we be disabling closed loop when tuning AFM like older vehicles?

Posted: Wed Sep 11, 2019 9:13 am
by Spunkster
you should not disable closed loop when tuning.

Re: Should we be disabling closed loop when tuning AFM like older vehicles?

Posted: Wed Sep 11, 2019 2:51 pm
by gtfrede07
Allow me to rephrase. Should we limit the long term trim percentage to zero?

Re: Should we be disabling closed loop when tuning AFM like older vehicles?

Posted: Thu Sep 12, 2019 2:32 pm
by Spunkster
Yes , but only if your are tuning the AFM.

Re: Should we be disabling closed loop when tuning AFM like older vehicles?

Posted: Fri Sep 13, 2019 11:23 am
by gtfrede07
I would suggest adding this to the help file, would have saved me some time. I had a hunch we should be but got the results I needed anyway, just took me a lot longer.

Re: Should we be disabling closed loop when tuning AFM like older vehicles?

Posted: Mon Sep 16, 2019 8:57 am
by Emount91
gtfrede07 wrote:
Wed Sep 11, 2019 2:51 pm
Allow me to rephrase. Should we limit the long term trim percentage to zero?
How do you adjust Long Term trim limits without affecting short term?

I've been adjusting my AFMs based on my short term trim results, and my long term trim moves too when I make that adjustment.

Re: Should we be disabling closed loop when tuning AFM like older vehicles?

Posted: Mon Sep 16, 2019 9:13 am
by Emount91
Spunkster wrote:
Thu Sep 12, 2019 2:32 pm
Yes , but only if your are tuning the AFM.
If i have been tuning my AFMs based on my short term trim trends (AFM.v X short term %), should I make the minimum and maximum for long term 0%?

What would this do to the way the car feels and drives? and would I also want to limit short term in any way?

Re: Should we be disabling closed loop when tuning AFM like older vehicles?

Posted: Tue Sep 17, 2019 4:51 am
by gtfrede07
its under closed loop parameters. limit the long term trim percentage to 0%. I did mine for the last week or so to see what if any effect it had and am about to enable it again. Didnt change much of anything . Just a faster way to calibrate afm when starting from scratch.

Re: Should we be disabling closed loop when tuning AFM like older vehicles?

Posted: Tue Sep 17, 2019 5:27 am
by Emount91
gtfrede07 wrote:
Tue Sep 17, 2019 4:51 am
its under closed loop parameters. limit the long term trim percentage to 0%. I did mine for the last week or so to see what if any effect it had and am about to enable it again. Didnt change much of anything . Just a faster way to calibrate afm when starting from scratch.
Thanks man, what makes it faster?

And shouldnt we do this with short term while tuning AFM.v X short term?

Re: Should we be disabling closed loop when tuning AFM like older vehicles?

Posted: Tue Sep 17, 2019 5:39 am
by gtfrede07
Basically it keeps the global fueling adjustment for closed loop not functioning while you calibrate the afm table. You would want to dedicate a full day to doing this. Not something I would do right before a commute to work or anything as your limiting the ecu's compensating ability.

Re: Should we be disabling closed loop when tuning AFM like older vehicles?

Posted: Tue Sep 17, 2019 6:44 am
by Emount91
gtfrede07 wrote:
Tue Sep 17, 2019 5:39 am
Basically it keeps the global fueling adjustment for closed loop not functioning while you calibrate the afm table. You would want to dedicate a full day to doing this. Not something I would do right before a commute to work or anything as your limiting the ecu's compensating ability.
Gotcha, what I'll probably do is keep tuning with it on during the week, then sometime this weekend turn it off and see how much my short trim mean changed.

Re: Should we be disabling closed loop when tuning AFM like older vehicles?

Posted: Tue Sep 17, 2019 6:53 am
by gtfrede07
That is exactly what I did.

Re: Should we be disabling closed loop when tuning AFM like older vehicles?

Posted: Tue Sep 17, 2019 7:31 am
by Emount91
gtfrede07 wrote:
Tue Sep 17, 2019 6:53 am
That is exactly what I did.
Should I continue adjusting my AFM values based on what I see with L.TRIM disabled?

Re: Should we be disabling closed loop when tuning AFM like older vehicles?

Posted: Tue Sep 17, 2019 8:17 am
by gtfrede07
Yes. Proceed the same way. When happy with the s trim; re-enable l trim. I am personally going to limit mine to 5% +/-. All this would help with is the tune remaining close to optimal should the oxygen sensor start failing or if an exhaust leak would develop later on. Would not let the trims get completely out of whack based on false readings later in the cars life.