AC idle tuning
I think i changed my stit, ltit, and ac airflow adder limits all to 3.0 g/s (i'm going from memory here since my laptop crashed). Also you may want to enable stall saver because that will disengage the ac clutch if your rpm drops below a certain point. Oh yeah, I also made my ac idle speed 850 with my normal idle speed at 800. Besides that, i think if you make sure all the normal stuff is good you should be set.
Get your ltit right with a/c off. Then when you turn on your a/c see what the a/c airflow is and what the stit's jump to. You will probably need more a/c airflow. With moderate to big cams you usually will see about 2-4 on a/c air flow, but the stits will rise high trying to add enough airflow. If this is the case you need to add more a/c airflow.
Would someone be willing to look at a log of mine? I can do fresh log tomorrow. I will start car, log, and let sit there until it gets to operating temp.
From what I have noticed for some reason, is I log my idle while driving is that bad?
I notice my Ltit, to be -.08 all the way through, then after car warms up and gets hot it jumps to -.32 or something crazy. Doesn't make sense to me. That is with AC off.
With ac on, my Ltit/Stit goes to zero, and there is something in hp tuners called a/c airflow or something like that. If someone could get me on track would be very much appreciated.
From what I have noticed for some reason, is I log my idle while driving is that bad?
I notice my Ltit, to be -.08 all the way through, then after car warms up and gets hot it jumps to -.32 or something crazy. Doesn't make sense to me. That is with AC off.
With ac on, my Ltit/Stit goes to zero, and there is something in hp tuners called a/c airflow or something like that. If someone could get me on track would be very much appreciated.
So basicly, the ECU keeps track on how much air to add when the a/c compressor engages? This is limited to .5 in the stock tune? In reality cammed cars may see a much bigger spread between a/c-off and a/c-on airflow. If you have perfect idle trims and you turn on the a/c and lets say it requires .75 additional air, once the a/c trim reaches it's max difference ( .5 ) it starts to adjust the stit to the remaining.25. Then when you turn the a/c off, your stit is still at .25? So the a/c additional airflow limit ( .5 ) needs to be upped?
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Originally Posted by GuitsBoy
So basicly, the ECU keeps track on how much air to add when the a/c compressor engages? This is limited to .5 in the stock tune? In reality cammed cars may see a much bigger spread between a/c-off and a/c-on airflow. If you have perfect idle trims and you turn on the a/c and lets say it requires .75 additional air, once the a/c trim reaches it's max difference ( .5 ) it starts to adjust the stit to the remaining.25. Then when you turn the a/c off, your stit is still at .25? So the a/c additional airflow limit ( .5 ) needs to be upped?
You have a pid for a/c airflow. You need to get your LTIT in check with the a/c off. Then turn on the a/c. You will see an a/c airflow amount on the a/c airflow pid. It is somewere around 2-3 stock. When you put in a moderate to big cam, this is not enough airflow. You need to tune it like you do the LTIT's. With the a/c on look at what the stit's do. If they go way positve, then you don't have enough a/c airflow.. This is just like stit's and ltit's. you add airflow until the ltit's and stit's get around 0. I actually like them a little negative (better to more airflow then not enough). Except with the a/c airflow you only use the stit's to see what adjustment you need to make to the a/c airflow.
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Originally Posted by Michael Ozorowsky
Would someone be willing to look at a log of mine? I can do fresh log tomorrow. I will start car, log, and let sit there until it gets to operating temp.
From what I have noticed for some reason, is I log my idle while driving is that bad?
I notice my Ltit, to be -.08 all the way through, then after car warms up and gets hot it jumps to -.32 or something crazy. Doesn't make sense to me. That is with AC off.
With ac on, my Ltit/Stit goes to zero, and there is something in hp tuners called a/c airflow or something like that. If someone could get me on track would be very much appreciated.
From what I have noticed for some reason, is I log my idle while driving is that bad?
I notice my Ltit, to be -.08 all the way through, then after car warms up and gets hot it jumps to -.32 or something crazy. Doesn't make sense to me. That is with AC off.
With ac on, my Ltit/Stit goes to zero, and there is something in hp tuners called a/c airflow or something like that. If someone could get me on track would be very much appreciated.
let me see if I got this straight: What I do is start scanning STIT/LTIT. Look at LTIT, let's say is -.08, then (with hp tuners) I go to my base running air flow, and -.08 from whatever temps necessary. Then, I turn a/c on, and look at my STIT, what table do I modify? Could someone please explain this as easily as possible?
take a look at my writeup on RAF (and many other idle related things) at http://redhardsupra.blogspot.com/200...le-tuning.html
just a quick advice: for Idle tuning, set your scans to g/sec, as the numbers come out much more precise than in lb/min so you get 20g/sec as compared to some 0.07lb/sec or something. same thing, better display.
just a quick advice: for Idle tuning, set your scans to g/sec, as the numbers come out much more precise than in lb/min so you get 20g/sec as compared to some 0.07lb/sec or something. same thing, better display.
from what i have found the RAF has nothing to do with the ac airflow, of course if its in line the better but what all the guys are saying about increasing adapt idle limits is a good place to start at if all your other idle stuff is inline
TECH Enthusiast
Joined: Mar 2004
Posts: 647
Likes: 0
From: Australia
I cant see any specific RAF value for AC on. However, I can see PID airflow decay rates for AC ariflow. Try doubling the Proportional and Derivative decay rates if your AC increases airflow ridiculously high and see if that helps.
FormerVendor
Joined: Jan 2003
Posts: 525
Likes: 0
From: Melbourne, Australia
AC airflow is torque based. You can try increasing the AC torque numbers under Engine -> Torque Mgt, Engine Torque if your STITs are moving too far positve when the AC is on.
Chris...
Chris...
