The MAF sensor has been removed from the air filter housing lid and the holes plugged - the horses should be able to breathe now:
[Linked Image]
[Linked Image]

Here's the reason that auto-tune doesn't work at idle rpms:
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There are a number of parameters that affect the operation of auto-tune. Note that there are no menus to configure auto-tune in MegaTune (other than the EGO parameters). All the other data that MegaTune displays in dialogs for you to edit is stored somewhere inside your MegaSquirt; the tuning parameters for auto-tune are just MegaTune-specific data and really have nothing to do with MegaSquirt. This means that you need to edit the custom.ini file to make changes to the tuning algorithm's parameters.

allowAutoTune = on
corrector = egoCorrection
Vertex tolerance parameters
xRadius = 200 ; rpm
yRadius = 7 ; map
Tuning block parameters
xLimits = 1500, 4000 ; rpm
yLimits = 60, 90 ; map
zLimits = 10, 200 ; VE
Controller parameters
initialStartupInterval = 1.0 ; seconds
updateInterval = 1.0 ; seconds
proportionalGain = 0.5
lumpiness = 5 ; percent
The radius (or vertex tolerance parameters) is how near to a vertex the operating conditions must be before the VE will be adjusted. For example, with the above settings, auto-tune will adjust a vertex if the operating point is within 200 RPM and 7 kPa of that vertex. If you increase the radius parameters, which would allow tuning farther from a vertex, then you may be changing the wrong vertex (typically four are involved at any given time, but auto-tune only changes the nearest one). The radius parameters try to minimize this error by only tuning when the nearest vertex has overwhelming influence.

For the limits (or tuning block parameters), "X" is RPM. Y is normally MAP, TP or load. Z is the VE itself. The limit parameters box the tuning points, no changes will be made outside the box. The radius parameters dictate how close the operating point must be to the tuning point for auto-tune to operate, if the operating point falls outside this smaller box, then no action is taken. If you change the limits, then you don't change the accuracy or speed, just the region that is valid for tuning.


The controls are set so that normally AutoTune is disabled in the idle bins because it's better to tune it to
what is working well than a preset air/fuel ratio. But there is a way to deal with the "Tuning point is outside window" message if you want to extend the auto-tuning range:

In "car1" folder, open the mtCfg folder inside this directory. There's a file in there called custom.ini. Open it with Notepad or a similar text editor. You'll see a block that begins with [AutoTune] and a couple of computer-speak if-then statements. You want the block that either begins with "#elif MS_II" or some note that it works with MS-II. Inside that block, you'll see a set of notes like this:

xLimits = 1200, 5000
yLimits = 20, 90
zLimits = 10, 150

The xLimits control the RPM range where AutoTune works, and the yLimits control the range of MAP values where it works. The zLimits controls what it can set the VE table to. Adjust these numbers to put the AutoTune range where you want it to be. However, it's probably better to tune the idle by hand. I might try changing the rpm floor limit if I can't get it to work like I want..... so far, the new VE table (yes, I've generated another) seems fine for idle characteristics.

This time I've told the VE table generator to expect the following:

CID = 181
Cyl = 6
Idle = 650 rpms @ 33 Kpa
HP = 250 @ 5500 rpms @ 150 Kpa (~7 psi)
TQ = 275 @ 5000 rpms @ 150 Kpa (~7 psi)
Redline = 6000 rpms

It's scary that I'm beginning to understand the relationship of the VE table to the other data. <img src="/forums/images/graemlins/lol.gif" alt="" /> I do think the MS manual could be better written. As an example, I've found my initial concern about EGO correction to be valid and a sign that something is out of kilter. On the first VE table, I was getting a surging idle and showed 170% EGO correction with a VE value of around 30. After I generated a new VE table with higher values around 60, EGO correction was reduced to about -0-... just a small hunt within 1-2% each side of the target AFR of 13.5:1 that I set in the AFR table. I don't see why the writers of the MS manual couldn't suggest that you first tune the VE table based on limited EGO correction, before tuning for lowest MAP. <img src="/forums/images/graemlins/evil.gif" alt="" />

Frank