Everything there is to know about MegaTune Auto-Tune

MiseryQ · Post by **MiseryQ** » Mon Sep 05, 2005 4:21 pm

Very Nice! I was hoping for this since I used Pers' RV8Tune.
Went for a drive and it does'nt have the bad habit of leaning the VE on a long decel like RV8Tune did.

I ran the before and after VEXs through a comaparitor.
While I need to check my EGO settings to double check, it looks like autotune will make adjustments outside of the EGO settings, i.e. I should be open loop at 75KPA but it made adjustments over that.

I attached the saved comparison as an HTML and included the datalog of the drive.
I'll drive it again tomorrow morning.

Megatune just got even better! What are you gonna do next? (:

Post by **efahl** » Mon Sep 05, 2005 4:42 pm

MiseryQ wrote:Went for a drive and it does'nt have the bad habit of leaning the VE on a long decel like RV8Tune did.

Q,

But it very well could, I think you just got lucky with the settings that I've got hard-coded right now... It may also be that whatever code you are running now has EGO correction disabled during decel and the old code didn't? (Could be the algorithms, too, I just used Per's concept and didn't really look at his implementation.)

Here's a sanitized version of the code, it's almost too trivial to even mention:

Code: Select all

   if (timeNow() >= nextUpdate) {
      if (atp.insideWindow(vX, vY)
       && atp.nearVertex  (vX, vY, XBIN(iXBIN), YBIN(iYBIN))) {
         double egoCorr = mdb.getByName(S_egoCorrection, 0);
         double veCurr  = mdb.getByName(S_veCurr,        0);
         double steps   = atp.pGain * veCurr/100.0 * (egoCorr-100);
         if (steps != 0 && z->incRaw(steps, iZVAL)) {
            mdb.cDesc.send(z, iZVAL);
         }
      }
      nextUpdate = timeNow() + atp.dT;
   }

While I need to check my EGO settings to double check, it looks like autotune will make adjustments outside of the EGO settings, i.e. I should be open loop at 75KPA but it made adjustments over that.

That is correct, I have not put any real limits on it yet (see above), so it will just keep on correcting down to 0% if that's what EGO correction says to do...

Megatune just got even better! What are you gonna do next? (:

I'm thinking I'll learn to tap dance (I took up unicycle riding about 10 years ago).

Eric

WolfGTI · Post by **WolfGTI** » Mon Sep 05, 2005 5:21 pm

Here's a look at the 3D maps before and after the first run with the autotune on.

WolfGTI · Post by **WolfGTI** » Mon Sep 05, 2005 5:33 pm

efahl wrote:
But it very well could, I think you just got lucky with the settings that I've got hard-coded right now... It may also be that whatever code you are running now has EGO correction disabled during decel and the old code didn't?

Eric

How do you disable EGO during decel? - I have been tryiing to get my ECU to do this.

MiseryQ · Post by **MiseryQ** » Mon Sep 05, 2005 7:00 pm

WolfGTI wrote:How do you disable EGO during decel? - I have been tryiing to get my ECU to do this.

What version of code are you using?
MSNS-E has "overrun fuel cut" standard B&G does'nt.

"Trivial"? (:

On my way to work I'll see what happens with a highspeed decel on the highway. We'll test my "luck".
I'm gonna have some fun testing this.

WolfGTI · Post by **WolfGTI** » Tue Sep 06, 2005 4:44 am

MiseryQ wrote:
WolfGTI wrote:How do you disable EGO during decel? - I have been tryiing to get my ECU to do this.
What version of code are you using?
MSNS-E has "overrun fuel cut" standard B&G does'nt.

"Trivial"? (:

On my way to work I'll see what happens with a highspeed decel on the highway. We'll test my "luck".
I'm gonna have some fun testing this.

I am using MSnS-Extra, code 025n. I know there is the over run fuel cut, I was hoping there was another way other than cutting the fuel completely, unless that method is completely harmless on a naturally aspirated car.

Post by **efahl** » Tue Sep 06, 2005 6:40 am

Full fuel cut is completely safe, it's like stalling the motor. If you are doing it on decel then you won't even know it's happening (try coasting in gear and switch the ignition on and off, on my cars I feel no difference).

Eric

Post by **efahl** » Tue Sep 06, 2005 6:44 am

WolfGTI wrote:Here's a look at the 3D maps before and after the first run with the autotune on.

Well, it sure is uglifying the map... It mostly appears to be leaning things out, but there is that one rich hump left of center at the back.

Do the results look trustworthy to you? (They don't to me.)

Eric

oddcomp · Post by **oddcomp** » Tue Sep 06, 2005 6:50 am

i run the fuel cut and its great especially on my low compression subaru turbo motor

oddcomp · Post by **oddcomp** » Tue Sep 06, 2005 6:58 am

hmm can't get figure out how to get the autotune turned on in msnsextra 025n9