Understanding Idle AFR

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mustang70

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I'm on my phone so I can't look things over, but would it be because the idle VE table needs to be adjusted? I have mine turned off so the idle uses the main VE table.
 

a91what

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If I remember correctly you are tuned MAF, so there are three ways to take care of the problem.
1. Use the ve1 trim table and reduce the value in the range in question.
2. You have a secondary trim table setup, the solution is the same as above.
3. This one starts by zeroing the ve1 trim tables and any other ve based trims you are using.
Now we need a datalog to work with, keep in mind the ve tables have to be zeroed already.
Let's create a few fields.....
MAF millivolts = [MAF volts]*1000

MAFcorr2 = [Field.AFR]*[Field.egoCorrection]*[VE2]/(10000*[AFR 1 Target])*100

Now this can be used to build a scatterplot to correctly adjust the maf curve, once you have it very close you can go back and setup your other trim tables.

Some of this information was courtesy of

From <http://www.msextra.com/forums/viewtopic.php?f=134&t=49504&fbclid=IwAR3hTq6BbgdPEaFA40RtjqfD0qxZUCTLuol_yaQQTebNpbY-1gWvKajLj1g>
 

Blown88GT

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Your response didn't answer the questions asked:
...
Is this why?
EGO Control is only active above 1200 rpm...so ignore readings below?

From the datalog, it appears that it never uses the VE2 trim table, even though it is enabled as Alpha-N.
 
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a91what

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The question was how do you reach target... you do that by adjusting the ve correctly.
Ego can be used to pull some fuel lower the rpm threshold
 

Blown88GT

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The question was how do you reach target... you do that by adjusting the ve correctly.
Ego can be used to pull some fuel lower the rpm threshold
That was a statement, not a question.
"Ego can be used to pull some fuel lower the rpm threshold"
Is this 2 things to do or 1?
1. Ego can be used to pull some fuel.
2. lower the rpm threshold. (This answers the question.)
OR
1. Ego can be used to pull some fuel by lowering the rpm threshold. (This also answers the question.)
It's been at 1200 rpm, forever. Probably should be at 600 rpm, let it correct all the time. Idle is closed loop at 850 rpm.

Small changes in words change the whole meaning.

I know you're on vacation without a laptop, responding on a dumb phone, using 2 thumbs.
Time to Repair the Phone.
 
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Blown88GT

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I guess the "thumbs up" means go for it.
I found a thread on the Corral that addresses this.

Probably need to adjust the PID settings, too.
I have no explanation why I'm still on the default settings after 5+ years.
1578053240741.png

Still having random issue with the LC-2 wideband controller. Sometimes takes 5-10 minutes for the controller to become active.
 

a91what

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You will want to set it to something like..
P=30
I=45
D=0 [1-4 works will to calm small oscillation]

Then work on mainly the P term first until it starts to swing then back it down...
Use I term to get the AFR to target not enough and it will never reach the target value.
The D term is like pumping the breaks as you get closer to target, use this sparingly if at all.
 

Blown88GT

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Working much better with these settings.
Also able to drop the target rpm to 800.
The too rich smell at idle is gone.
Should help the fuel economy, too.
Put the ignition on before starting to insure that the WBO2 heats up & it's controller goes online.
They say this is bad for the sensor (cold fuel on a hot sensor), but I did it for a long time with no adverse results, then stopped when I heard that it was bad. I bought a spare sensor when I thought the original was bad.
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