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Closed Loop Proportional Idle

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Old 01-20-2005, 05:05 PM
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Default Closed Loop Proportional Idle

Has anyone learned anything about this??? I searched and searched and everyone seems to be really stumped about it...

I wanna know if adjusting these settings can improve rich/lean conditions at idle...
Old 01-20-2005, 10:23 PM
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Originally Posted by txhorns281
Has anyone learned anything about this??? I searched and searched and everyone seems to be really stumped about it...

I wanna know if adjusting these settings can improve rich/lean conditions at idle...

It depends.

The proportional tables determine how much fuel to add or remove to make the O2 sensors switch from rich to lean (and vice versa).

Think of it as a thermostat for heating and air conditioning to keep your room at 70 degrees. It has more to do with closed loop stability than making the engine run rich or lean.

The rich lean tables determine where the AFR at closed loop should be.
The proportional tables determine how much to quickly add/remove to get there.

When the VCM makes a change, it expects to see the change.
That is what the integrator delay table is for. If the change does not happen below those table times, the VCM will add or subtract fuel to try and center itself on the rich lean tables.

Most of the time you will not need to adjust these tables unless your race car has a radical cam and is letting air into the exhaust to show a false lean condition. Or you have increased the injector size substantially.


Ken
Old 01-21-2005, 09:24 AM
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the lower the lobe seperation the more it is affected, like 108 ls or 110 114 and higher normally arent a problem.
Old 01-21-2005, 10:13 AM
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I changed the O2 mV switch points in order to lean out the target AFR slightly and it worked. I started playing around with the proportional table in order to stabilize the AFR better. It was more of a hit or miss thing. Watch the O2 mV in scanner and determine how the changes increase or decrease the overshoot. You want to see the keep O2s flipping high and low without too much clipping. Perhaps clipping more low for higher AFR and clipping high for lower AFR. Hope that made some sense.
Old 01-21-2005, 05:25 PM
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Originally Posted by SSpeedracer
I changed the O2 mV switch points in order to lean out the target AFR slightly and it worked. I started playing around with the proportional table in order to stabilize the AFR better. It was more of a hit or miss thing. Watch the O2 mV in scanner and determine how the changes increase or decrease the overshoot. You want to see the keep O2s flipping high and low without too much clipping. Perhaps clipping more low for higher AFR and clipping high for lower AFR. Hope that made some sense.
mmm a little... but perhaps you could try and give an example of what you're talking about... What exactly would i be looking for as far as the effects of the CLIdleProp?

Originally Posted by wait4me
the lower the lobe seperation the more it is affected, like 108 ls or 110 114 and higher normally arent a problem.
Also, my cam isn't "radical" but it is on a 111 lsa so does that mean that I coudl benefit from playing with this??? In case you haven't been following the "MAF table/VE screw up" thread I have a rich condition at idle and low TPS/low rpm driving... I have tuned out my VE to be consistent and my MAF table is also dialed in well, but when commanding stoich AFR the computer seems to have trouble at the above mentioned driving conditions... It's getting really annoying... Just wondering if the CLIdleProp is something that can help this problem... Any suggestions?



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