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Old 05-09-2011, 10:37 AM   #1
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Default VE analyze autotune and MAT correction table

I know I know, it's been beaten to death, but I want to understand what is going on.

I've received a little conflicting information, but I think it might be due to how I was asking the question. I asked on MSextra if VE analyze takes into account the MAT correction table while autotuning. The response was yes. Reverent I believe, said no. I think Reverent is right, but help me understand what the algorithm IS and IS NOT taking into account while autotuning.

How is the Autotune algorithm handling the ideal gas correction (Gair) and the MAT correction table?

Would someone please spoon feed this to me, and then place it in a useful save post. Not understanding this can completely waste a dyno session.
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Old 05-09-2011, 10:48 AM   #2
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I'm almost positive autotune looks at Gair% when making corrections, but I could be wrong.

Why not create an Anti-Ideal Gas Law table in your MAT corrections table? Cause right now, when you start seeing intake temps higher than 80*F the MS is going to want to pull fuel like a bitch. This oculd screw up your tune and any autotuning.

You'll end up with this:

matcorrectionbobi.jpg?t=1293264325

This pretty much causes Gair to stay at 100% regardless of the intake temps (assuming the MAT correction value is 100%).

I personally think the code is too aggresive, while it may be the laws of physics - in terms of fueling it doesn't seem to be the case.
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Old 05-09-2011, 11:43 AM   #3
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note that you can custom filter for a range of MAT values if you want.
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Old 05-09-2011, 11:56 AM   #4
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Are you zeroing this table while autotuning, or tuning with this table as it is above?

Are you using 100% correction? I have mine set to 50%. I'm not sure if it matters.

My plot at 50% is:

20 -2
60 0
76 0
86 1
103 3
145 6

This was based on countering the Gair value from a zeroed MAT correction table.

Quote:
note that you can custom filter for a range of MAT values if you want.
yeah, I guess I could filter out the range that i would expect to see while sitting at a traffic light since in boost will be much hotter, and cruise will be a cooler. I might play with this.
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Old 05-09-2011, 12:08 PM   #5
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Mine's close to what you quoted, since mine's at 50% as well. I really need to put it on my stim and set it there, making sure it's accurate in canceling it out.

I'm leaving that table as is, when autotuning or not. I'll adjust it at idle for extreme intake temps if need be. But for now, I do not like the ideal gaw law code and how agressive it pulls fuel with higher MAT temps. I see high temps in boost, so it was effecting me on the dyno and hot restarts were lean like what when they went past 80*F.
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Old 05-09-2011, 12:08 PM   #6
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How is this being handled?.......

I'm tuning at 75 degrees ambient, so my IAT is 85 degrees. I want to autotune to full boost and see 125 degree temps at the upper kpa fuel cells.

My cruise cells are now being tuned at 85 degrees, max boost at 125 degrees, and some gradient between cruise and max boost. If I autotune with the MAT correction table nulling the Gair (100%), then I would have to add a correction on top of it to actually take into account the changing temps. Nevermind, because as temp decreases it isn't adding as much fuel, so it is taking into account the air correction.

By zeroing the table and tuning at 125 degrees it is tuning with significant fuel pulled, but it is meeting the afr criteria. If I then change the MAT correction to add fuel at 125 degrees to counteract Gair, then won't it be rich at 125 degrees?
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Old 05-09-2011, 12:12 PM   #7
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I did a lot of testing of underhood temps. I bet your AIT is really seeing 85*F.

In fact, my AIT just off the IC was cooler than a second AIT sensor when sitting behind the firewall, when sitting under my air filter in my cold air box, and when sitting underneath my headlight.

and who's to say you really need to subtract fuel when the temps get that hot?

the best way to judge this would be a hairdryer on your AIT sensor/intake at idle. If the hot temps, with no corrections, make you go rich, then you need some correction...if not, then you dont.

I'll take my chances with it going rich in boost if the AITs get hot enough to require it before I'd want it to pull fuel in boost.


As of now, between 45-80*F I don't need any corrections. My AFR is on target at idle between those intake temps with zero Gair correction.
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Old 05-09-2011, 12:20 PM   #8
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Well then, I will continue to tune with my MAT table in tact. A good way to determine the values for MAT correction table is to zero the table and start datalogging on a cool morning. You will see the Gair that is being applied relative to the AIT. Make sure you get into boost so that you can get the high AIT temps.

This is probably known to most, but since I wanted this to be an educational thread I thought it might be helpful.
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Old 05-09-2011, 12:30 PM   #9
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a stim is easier


or take the table i posted (which was done on a stim), put MAT correction value back to 100% and whamo! I just havent confirmed it myself, someone else did this and posted with an MS2. But my values are more or less half those.
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Old 05-09-2011, 12:48 PM   #10
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Think you could post you non linear correction table brain? (That you use with 50 percent correction value). I havnt ran mine up to extreme hot temps like 140 yet so I haven't set those values yet...but it'd be nice to get it ballpark close. Like everyone else I go crazy lean when it gets even a little bit hotter.

Edit: nevermind just read your above post, ill just use those numbers with 100 correction value
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Old 05-09-2011, 03:35 PM   #11
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im going to try brains at 100. i had to increase mine around 100* to satisfy idle afr, but gair wasnt pulling as much as i am adding.
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Old 05-09-2011, 03:39 PM   #12
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I feel like I am having this same issue, but I cannot find MAT correction on TS, Ive searched through TS with no luck.
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Old 05-09-2011, 03:41 PM   #13
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yeah if you start to add too much, you'll start going rich like whoa in boost. I had that issue the last dyno day we had in Nov. I arbitrially added in correction to help revent heatsoaking at idle and going lean. didn't realize what effect it had in boost.

I probably should have guessed something was up when I was averaging less than 20mpg.

having the stupid voltage offset in TS from my LC-1 didn't help. 1 full point richer from that alone.
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Old 05-09-2011, 03:56 PM   #14
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Quote:
Originally Posted by Braineack View Post
yeah if you start to add too much, you'll start going rich like whoa in boost. I had that issue the last dyno day we had in Nov. I arbitrially added in correction to help revent heatsoaking at idle and going lean. didn't realize what effect it had in boost.

I probably should have guessed something was up when I was averaging less than 20mpg.

having the stupid voltage offset in TS from my LC-1 didn't help. 1 full point richer from that alone.
Did you add a manual offset to get the gauge and TS to read the same? I adjusted mine to where it stays roughly .1 within TS. I'm still not sure if its is a good idea or if I should leave the TS AEM linear calibration alone.

MAT correction table is located under the "extended" tab.
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Old 05-09-2011, 04:04 PM   #15
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yes eventually I figured out that was the issue. my gauge and logworks read the same. TS showed 1 full point leaner. So when I tuned based off that I was 1 full point richer.

When calibrating my AFR table in TS, I use .2v instead of 0v for my 7.3X:1 value. everything matches up well now. Averaging 25mpg city.
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Old 05-09-2011, 05:17 PM   #16
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How about Ego correction? Do you have your closed loop O2 on when running AutoTune on TS?
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Old 05-09-2011, 05:50 PM   #17
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definitely not.

I'm revisiting my VE table using autotune.... I turn off EGO, set accel enrichments cutoff to like 999 revs/sec so it will never kick in, applied the above MAT correction values and tuning from there.

I changed one of my gauges on the lefthand side in autotune to Gair and mine stayed right at 100 the entire time in my last drive.... might have been flipping to 101 every now and then, but that could have been the tail end of warmup enrichments...

Basically I'm under the impression you want to kill all enrichments for VE table tuning... then once it's 90 percent there, add in accel enrichments, switch on EGO control for cruise if you'd like, etc. Just be mindful go easy on the throttle inputs when tuning the VE table... otherwise leanspikes will get compensated for in the VE table from autotune and you don't really want that, you want the VE table to be tuned for steady state conditions, then accel enrichments to take care of the lean spikes.
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Old 05-09-2011, 06:13 PM   #18
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i leave everything on! im hardcore like that.
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Old 05-09-2011, 06:22 PM   #19
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interesting, i thought you were "supposed" to turn the extra crap off initially for VE table, then start adding that stuff in. Shows what I know..
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Old 05-09-2011, 06:22 PM   #20
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VEAL will work fine with EGO enabled. I suspect it keeps track of the current VE value plus the EGO correction value and adds them together to get the new VE target.

I would leave your corrections in place and make a custom filter that addresses them.

you'll have to figure out the right variables to use if you don't already know them by going to the dashboard and viewing "output channel" for the specific gauge (which you may have to create to see). and then add in your filter.

remember that you are filtering for where you don't want VEAL to run. so if you put "rpm < 400" then it will not tune below 400 rpm.

here's what I use:

(tpsDOT > 50) || (rpm < 1900 && fuelload < 67) || (advance < 1 )

make sure to save the filter somewhere because if you hit "cancel" it goes away.

Basically I filter when TPS enrichments kick in, around idle, and when various limiters are enabled (the advance < 1 part)

&& means "AND"
|| means "OR"
() allow you to nest operations

so you could say "( airCorrection > 97 && aircorrection < 103 )
airCorrection is the output channel for Gair.
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