So, weve finally solved the noise, synch, etc issues in the duster by going fuel only with a msd ignition. Now i get ti tune.
It idles and free revs prettu well at this point. Idle is rich as hell. Somewhere in the 11s as i can read on the wideband.
I have autotune, but need the basics to start with i guess.
There's no difference really, in tuning fuel only. It's actually one less thing to have to mess with. Just start tuning it.
The whole "just start tuning it" is where the problem is.
Ive never successfully tuned anything efi.
I guess i need a "start here" kind of flow chart....
start with getting it to idle properly and go from there.
If you have your autotune working, then just start driving it around, pausing occasionally to burn the current buckets to flash. I haven't used the new popular Tuner Studio, but in the old MegaTune, it would tune up to some percent of the existing bucket, then go no further. So drive some, stop, flash, drive some more. Do that for a while and you will get a basic tune. Take that, load it up and then smooth it out. Like if one point is high and the points on both sides are low, make all three points in a line, more smooth. Let's say you have buckets at 2000, 2500, 3000 RPM and they are 75, 90, 85. Change them to like 78, 82, 87.
Is there a good writeup to use for autotune? I want to make sure im understanding it correctly so im not creating new problems.
As faras idle goes, is there a good writeup on stepper motor idle tuning?
Im really struggling with the software side of this
Just cant seem to wrap my head around it. Im out of play money to pay someone, so i have to learn if i want to drive this.
You set your target AFR for certain ranges before opening autotune. When you open autotune and start it just drive around, it will automatically adjust the fuel to hit the desired AFR for each cell. When you burn it to the ECU it applies the changes. Do this for a bit making sure you are driving in a way to cover most of the table and you should be pretty close.
Additionally, since im using the tach output on the msd box for rpm trigger to megasquirt, where do i get the signal for the in dash tach? Dont think it'll work from the coil.
Tuning is easy, but there are a lot of moving parts. Get on youtube and watch as many videos as you have time for.
If the car cold starts and idles ok, I would start on your VE table. I cant remember if MS has live table trace, but you should be able to lean out your idle with a couple of "-" keystrokes on your VE table in the appropriate area.
From there you can identify some data points every 500-1000 RPM and use the interpolate function. That will get you 99% there.
I'm happy to jump on the phone with you a bit if you would like.
In reply to EvanB :
Other than afr targets, are there any other settings? This megasquirt has been messed with by a bunch of other people in my efforts to fix it. Just want to make sure its operating the way its intended. When i opened it up last night, i got a light saying something about rpm threshold.
In reply to NordicSaab :
That would be fantastic! Not gonna lie, after the concussion in January im struggling with reading comprehension.....
In reply to Dusterbd13 :
Can't remember, it's been years since I did it.
EvanB said:You set your target AFR for certain ranges before opening autotune. When you open autotune and start it just drive around, it will automatically adjust the fuel to hit the desired AFR for each cell. When you burn it to the ECU it applies the changes. Do this for a bit making sure you are driving in a way to cover most of the table and you should be pretty close.
This is exactly where you want to start- know what a/f you want. This table may look hard, but it's not- I'd bet that the one you have in the calibration is not a bad one- but I honestly don't know what the name of this function is in MS, since I've never used it.
One other thing to add to Evan's post, make sure you start with a warmed up car. Deal with the cold compensations later.
Once you get it running and auto tuning, start with idle and let it settle.- then:
-slow engine ramp up while standing still
-slowly drive the car around, a lot. Give the system plenty of time to re-calculate what it is auto tuning.
- then drive more and more "aggressively"- a few times, use the brakes to do a higher load version of the driving around. Don't do it much, so the brakes don't get too hot.
Until you are really familiar with calibrating, just focus on the one item at a time. As long as it's idling, and not stalling- don't mess with the idle control, yet. Just focus on getting the fuel right.
The more you get comfortable with what the autotune is doing, then the more you can do it yourself. What little I've done in MS, it's a pretty sweet tool for the shade tree mechanic.
How do i make an educated guess what afr to plug into the table? Can we relate it to tuning a carb?
If in air-fuel terms, go with 14.6 at all points other than the top end, where I would start with 12, and blend that into the 14.6.
I'm sure someone can post a table that looks like that.
The afr table on the left side is labeled afr load kpa, bottom is rpm.
Higher kpa values (100, 80, etc): is that low vacuum (heavy throttle) or high vacuum (light throttle)?
Higher kpa is low vacuum, heavy throttle.
Here is a sample chart from the megamanual.
And while that chart has a lot of different a/f listed on it, including rich at idle, KISS, and keep it all 14.6 from 75 and under, 12 at 95 and up, and blend it together.
You can tweak this table later if you need to.
Evan- do you recall if MS allows the fuel to be turned off during closed throttle decelerations? If it does, then the decel lines become pretty irrelevant, anyway.
Cool. Thanks.
Dusterbd13 said:Additionally, since im using the tach output on the msd box for rpm trigger to megasquirt, where do i get the signal for the in dash tach? Dont think it'll work from the coil.
You might be able to split the signal (once the amperage is enough for both inputs - it should be...), or you could set up a tach output on the Megasquirt to drive your tach. If your tach is expecting a spike signal from a coil, you'll need to make a tach driver device to turn the square-wave signal from the MS into a high-voltage spike signal:
http://www.msextra.com/doc/ms2extra/MS2-Extra_Hardware.htm#tachoout
My Corolla uses the Megasquirt's tach output with a high-voltage tach driver. Using the MS output is the more flexible option, if the number of pulses is different on the MSD ignition vs. stock, you could correct that on the MS.
alfadriver said:Evan- do you recall if MS allows the fuel to be turned off during closed throttle decelerations? If it does, then the decel lines become pretty irrelevant, anyway.
It does, there is a checkbox under one of the settings that will cut fuel. I think it is set to cut fuel on closed throttle deceleration by default.
alfadriver said:Evan- do you recall if MS allows the fuel to be turned off during closed throttle decelerations? If it does, then the decel lines become pretty irrelevant, anyway.
It sure does, with fancy fuel & spark return options too. So the decel lines are most useful for setting how much overrun exhaust crackling/flamethrowing you want 
For ease you may want to change all your setting to Lambda. I will make tuning AFR's easier.
So my first attempt at autotune:
Warmed up the car. Set my idle manually with the idle stop set screw 875 RPM. Then I figured out that auto-tune was set to not operate below 1500 RPM so I changed that. Started Auto-Tune. Idle became far less rich. Did my best to hold steady state at various RPMs without moving. Don't know how long I took with that but 10 minutes tops. Then went through the neighborhood attempting to hold steady state in first and second gear while auto-tune was running. Save changes at every stop sign. Then went out onto the main road and ran it up to 4th gear where I tried to hold steady throttle States as long as I could. Saved all the changes when I came off the main road and came home. Maybe 5 miles at all. So where did I screw up? Asking for clarification not because the car is running worse.
Seems fine to me, it doesn't need long to make the adjustments so when i did it i just drove normally then increased load and tried to drive at varying load to hit as many cells as possible. Once you do that you can just smooth out any cells in the table that seem off or keep using auto tune to fine tune it more.
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