Wow... Patience guys
. I just wanted to compare some of your .msq's to see if it lined up with our findings over the weekend. I had some more testing to do before I could share anything that would be universally helpful -- but I think I can do that now, hopefully.
I can tell you that Ken and James both feel pretty confident it's not a code issue. We had a scope out in the parking lot for a while, along with using the trigger monitor tool in MegaTunix to view the triggers watching for anything funky in the ignition triggering. They couldn't find anything out of the ordinary there. James drew out the wheel pattern and traced it out, and we did change the wheel decoder settings at one point to what he felt may be the better way to set it up, but it didn't change the 'slight misfire' issue for me. It continued.
They kept going back to something in the config/tune. We checked out dwell, played with it a bit, it didn't seem to be the issue for me. Though for someone else it could cause a similar issue. It was running around stoich at idle, mid 14's really. Richened it up a bit to high 13's, better but still missing some. Tried 16deg ign adv, also 12, and 10, no change. Found something that should have been set long ago differently-- I had originally grabbed someone's map off the forums for the base settings back probably 6 months ago-- it was set to 1 squirt, simultaneous. That often isn't best on most motors-- generally 2 squirts alternating is better. We set it to that, and immediately the issue went away on my car. Purred like a kitten.
Looking at the 2 .msq's I recieved (yep, that's it) in response to this thread-- one of them had a REQ_FUEL setting in the recommended range of 6-15ms, and the other didn't. This can make idling a challenge if you're outside of this range. Both users DID have 2 squirts, alternating. So immediately I knew more experimenting was going to be needed. James and Ken are pretty confident this isn't a code issue-- and pretty confident it is a tuning issue, but I know they do want to see it resolved for people. What we found in VA was that going to 2 squirts alternating fixed it for me. The only other change we made was the wheel decoder settings, which I'll be glad to share. That could be related too though in my case it didn't seem to make a difference. On paper it sortof made sense why it could play a role, and in an intermittent sort of fashion like had been reported, and if that's it the new settings should resolve it.
Going further on the theory that worked for me. Different setups are going to have slightly different needs. If you're running different injectors, with different opening times (real opening times, not what's been guesstimated into MT), as well as vastly different size meaning vastly different REQ_FUEL numbers you're just going to have to play with this a bit. The theory is that in a batch/bank fire setup like this, particularly with 1 squirt simultaneous, you pretty much are always running two cylinders potentially lean as the fuel is firing at the same time on all 4 cylinders, but only 2 are close enough to firing time (at idle speed) to get good even fuel atomization in the cylinders-- the other two cylinders, especially the last one in the cycle, is getting fuel that's had time to 'settle' a bit, isn't as well atomized, etc.
But the stock ECU idles just fine right? Why not the MS? Well... it will idle just fine. What we have here I believe is something in the config/tune. On a stock car it's easy to nail-- my car now idles like stock. Purrs like a kitten. Every time. AFRs are now in the low 13's at idle once warmed up.
I leaned it back out to 14.7:1 and it started missing again. Hmmm... that's strange. No other changes, still 2 squirts alternating. So what the heck is the stock ECU commanding at idle-- well that's easy to check. 10 minutes later the stock ECU is in the car, I fire it up, let it settle in fully warmed up, and it's idling at 13.2-13.3:1. Rev the crap out of it, let it settle.... right back to 13.2-13.4:1 range. Leave and come back 10 minutes later (letting it idle), still at 13.2-13.4:1. Purring like a kitten.
The stock computer commands low 13's at idle too. My MR2 on the stock computer liked low 13's. Talking to Justin who works here now but is an ex-Subaru tech he said Subarus on the stock ECU idle in the mid-13's. This is pretty common as I've seen it repeatedly on different makes of cars. Engines make just a bit more power there than at 14.7:1, it makes for a smoother idle, which also makes for better recovery in the event of a stumble for any reason, or increased load, etc. All of which overall contribute to the bottom line of a smoother idle....
My belief-- after spending a good bit of time on this and working with the coders and hardware designers themselves on it (I should have taken a picture, Ken, James, Bruce, DieselGeek, Peter Florance, Dave (megatunix), myself, and several others all standing around this car with a scope, two timing lights, and multiple laptops.) is this--- we just need to tune a bit different here. 2 squirts alternating (for some 4 may work better), I'll get you the new wheel decoder settings in case that does play a role though it didn't seem to for us, and richen your mixture to the 13.2-13.3:1 range at idle once the car is warm.
As for the wheel decoder settings-- pic below-- make sure to check your base timing after changing this just in case it moves!