Tune 'n' 'charge 'n' tune

[Loren]

Turn OFF all of the enrichments until you've got a decent base map put together. Throttle response won't be great, but you should be able to get very good drivability even with the enrichments off. KISS. Fight your demons one at a time.

Idle tuning can be a big ol' gnarly demon to figure out. I can probably save you some time.

[twistedwankel]

can't let go of the gas

Right Steve. Never trust a fart.

[Native]

MS idle tuning is like rocket surgery.
https://www.youtube.com/watch?v=bZe5J8SVCYQ

"...which is called 'error'."
Lol. That part I understand!

[Native]

Fight your demons one at a time.

Right on. Base map demon first. I'll tell the others to form a single file line...

[Native]

Made a little progress today. Adjusted a couple other settings I missed, and got some low load AFRs reasonable. Idle and start are a little better, too.

[Loren]

Winning.

[Native]

Covered more ground:
I think I've got a pretty good basic tune laid down. General normal driving, and a bit of hooning, all give good AFRs, good throttle response, and smooth power delivery. Feels seat-o-the-pants strong, actually. Need to tweak a few areas, like start and Idle; throttle tip-in needs to be smoother; high load, low rpm (like floored in 5th at 2k rpm) is way too rich; gotta turn on and adjust lift-throttle fuel cut. Good progress and a nice success so far for me!

But I think next I'll finish mounting the computer itself, and swap that clutch slave.

The SC install is getting closer!

[Loren]

Awesome sauce.

[Solar]

The SC install is getting closer!

I guess a year closer, is closer.

[Native]

Lol. It looks so choice decorating the shelf in my garage.

[twistedwankel]

Not to worry, Steve.
We must be up to double or nothing against Brian by now?
I'm close to two ball ripping cars by now?
Oh that's right even Phillip "the alternate alien" cannot handle one of them.

I smell money.

The Mayor

[Native]

Well, the latest and greatest is just dull - hard-mounted the MS box itself. Properly routed and secured the vacuum tubing. Installed the new header blanket. Didn't make it to the clutch slave...
Still progress, though!

[Native]

https://www.youtube.com/watch?v=K8E_zMLCRNg

[Loren]

Go, Steve! Make stuff happen! Run your Megasquirted, Supercharged and custom-tuned Miata next season!

[Native]

^^^I'd like to...

Changed the oil today (it was time).
Oh, and I got the clutch slave done last weekend or maybe the one before - maybe now it won't lose fluid.

i've got the basic fueling pretty good, thanks to autotune. Pretty basic AFRs - 13.5-14ish around idle, 14-15 cruise, down to 12 under load. Fairly consistent. I haven't turned on fuel-cut under decel, so it actually goes a little rich, like 13.5-14 when coasting in gear. Good enough for now!

So, today I started futzing with the throttle tip-in. I did all of this sitting in my driveway in neutral, and fully warm. What I'm trying to fix is that upon first touch of the gas pedal, especially at idle or lower rpm, it momentarily goes quite lean, say, 17-18, or worse, and may want to stall. Kinda a pain moving off from a start - gotta rev a bit before applying clutch... Slower throttle application is worse than a sudden stab or just stepping on it 75% (yeah, I know, just floor it all the time and no problem...). I turned on acceleration enrichment, aimed to add fuel more quickly so the motor can do something with the extra air it gets when the throttle starts to open. Well, I didn't exactly fix anything. In fact, I made matters worse, in that touching the gas pedal leaned it out so much it died. And the idle got worse, too - lots of pulsing. I tried lots of different combinations of available settings.

So, I cancelled all the changes I made, turned off acceleration enrichment, and went to my ignition table, to mess with advance. As it sits, at idle, it's running about 17 btdc,and idles around 850 or so. I set it back to as low as 12*, which lowered idle rpm about 100. Then I went to messing with acceleration enrichment again, to only the same result - stepping on gas pedal from idle makes it lean out and want to die.

After about a half hour or so, I had enough, and the battery on my computer was about done. So, I put it back to where I started, and will do some more research, as obviously I don't have it quite figured out yet . Perhaps a richer idle to start with...

[Loren]

Bring it over sometime, Steve. I can help with that kinda stuff. It's hard to explain, and I don't feel like writing a novel, but I can walk you through it.

[Native]

Thanks.
I've read a bit more, and it seems as if it's a common issue, and everyone has a different solution.
But, I have some ideas to try - fuel, timing (I think you mentioned that before). I'm gonna muddle along a bit more before I hit you up!

[Native]

So, I jump-started the car Friday, and drove it around for a bit, if for no other reason than to charge the battery.
I then retarded the timing in idle cells, and this time just added fuel in the same cells. Imaging that, it now idles closer to the 750ish I'm looking for, and is much steadier and less dip when I lift off in neutral. But it now idles at an AFR of 11ish. Seems richer than it should be, but I decided to leave it for now.

Earlier I posted this:

What I'm trying to fix is that upon first touch of the gas pedal, especially at idle or lower rpm, it momentarily goes quite lean, say, 17-18, or worse, and may want to stall.

So, I data-logged it for all the world to see:

The top graph is the interesting one: yellow is AFR, white is rpm, and red is throttle position (the white trace in the middle graph is rate of throttle change, and red is "load"). Not that it matters, but I'm coasting in second gear fully off the gas, approaching a speed hump, with AFR 14 ish. The first major throttle jump is me adding gas as the rear wheels climb the hump. What you can see is that as soon as I open the throttle, load goes right up, and the AFR goes way lean, like almost 20:1, then goes super-rich, like 9:1, then comes up to the expected 12ish as I accelerate away from the hump.

That lean spike is pretty reliably reproduceable, but not always as extreme. It'll do it just revving from idle sitting still in neutral. I chose that section of my log as it was cleanest to see.

I'm going to take another look at my fuel and timing tables, and see where I'm at in low rpm-higher load cells, as a start anyway. Fun stuff - truly - I wish I could create more time to mess with it.

[Loren]

What you can see is that as soon as I open the throttle, load goes right up, and the AFR goes way lean, like almost 20:1, then goes super-rich, like 9:1, then comes up to the expected 12ish as I accelerate away from the hump.

You may be misinterpreting "load" in this context. I don't know why they label it that. One of the first things I do when I start playing is change that to "MAP". MAP is manifold pressure measured in kPa and is DIRECTLY related to throttle position. If you're NA, the more you open the throttle, the closer manifold pressure gets to the atmospheric pressure of 100-101ish. If you're boosted, obviously, it can go higher.

"Load" is EXACTLY the same reading, just translated to a "percentage". Kinda confusing if you ask me.

So, you're tipping in, it's going stupid lean, and then going stupid rich. Assuming your fuel table is well-tuned, that's probably a matter of tuning your throttle enrichment. If you've got enrichment disabled, what you're seeing is normal, especially if you have some O2 correction going on. Lean tip-in is normal if you don't have anything correcting it. The O2 goes lean, and if you have correction enabled, it adds more fuel, which causes things to go rich... and eventually it settles out.

This is just me guessing... don't know what you've got going on in your tune.

Once you get that tip-in fuel issue sorted out, you can greatly improve tip-in throttle response by playing with timing. Even when you go boosted, you can do some pretty significant timing enhancements in low-rpm, high-kpa situations. Then have it taper back down to "boost safe" levels as the revs come up.

Glad you're finding some time to play with it!

[Native]

If "throttle enrichment" is the same thing as "acceleration enrichment" then it's currently disabled. I had started to mess with that before, and only succeeded in making it worse. Will keep at it!