Hey guys, lets talk about AFR tables...

[the poi]

Dunno how many people are on the new MSnS code, but I cranked this out in about 5 minutes by guessing randomly on what seems like a good AFR. I have overrun fuel cut turning on under 40 kpa, so im not even bothering with an AFR for a kpa that low...
[code]
TechEdge Vlin table

Afrs
250 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0
225 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0
200 12.5 12.5 12.5 12.5 12.5 12.0 12.0 12.0
150 13.0 13.0 13.0 12.5 12.5 12.0 12.0 12.0
100 13.5 13.5 13.0 13.0 12.5 12.5 12.5 12.5
85 15.0 15.0 15.0 14.0 13.0 13.0 13.0 13.0
65 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0
50 17.0 17.0 17.0 17.0 17.0 17.0 17.0 17.0
1000 2000 3000 3500 4500 5000 5500 6500


plot this:
250 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50
225 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50
200 1.75 1.75 1.75 1.75 1.75 1.50 1.50 1.50
150 2.00 2.00 2.00 1.75 1.75 1.50 1.50 1.50
100 2.25 2.25 2.00 2.00 1.75 1.75 1.75 1.75
85 3.00 3.00 3.00 2.50 2.00 2.00 2.00 2.00
65 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00
50 4.00 4.00 4.00 4.00 4.00 4.00 4.00 4.00
1000 2000 3000 3500 4500 5000 5500 6500
[/code]

This is copied from an excel worksheet I made, its for use with the TE Vlin output, the plot table just hacks away at the chosen AFRs and makes the right voltage numbers. So if anyone wants it I guess I can email it to you or soemthing. In any event, real question is, how do my chosen AFR's look? This is gonna be a 60/63 turbo with a turbo cam to give anyone a rough idea...

[PetesDustyVolvo]

total nub question here.... but.... "fuel cut".... i thought only lh users had the pleasure of such problems???how would you still get fuel cut with MS?

[Hank Scorpio]

Not bad. It varries, my motor doesn't like running more than 12:1 AFR's (it actually pings if I do), some like more.

Over all, looks about right to me. What I do is:

0-5psi, 14:1
5-10psi: 13.5:1 (depending on CR)
10-15psi: 12.5-13.:1
16+ 12.5:1 or richer

[The Aspirator]

That looks great to me, roughtly the same as what I would do. Though for mileage I think I'd have it leaner at 100kpa, and maybe 13-13.5 at 125.

From memory and watching the wideband display while driving, I like 85 kpa to be about 14.5, and 100kpa to be about 14-14.5. Then richen it up for boost. The way I see it is if you want to tune for mileage, figure out where you spend most of your time cruising while daily driving. Probably 50-110kpa, and make it as lean as you can through there before it bucks. Above there is boost, give it what it needs. Start at 13.5 and go richer as you go up the scale.

What about when you decellerate? Wait, you've got an auto, does that change things???? When I decellerate in gear the wideband display goes full lean (45L), and when the engine is cold it stubles after every time I let off the gas. I'm wondering if I can do a warmup decel enrichment?

John

[The Aspirator]

Originally Posted by Snoop Dougy Doug

Not bad. It varries, my motor doesn't like running more than 12:1 AFR's (it actually pings if I do), some like more.

Doug how does your car do during warmup? When mine warms up it's pretty damn rich, sometimes 11:1 at idle. That might be too much, but it's doing alright, nowhere near good though during warmup.

John

[Hank Scorpio]

well mine likes to idle around 13:1. My warmup values are LOW (course it never gets that cold here).

It seems to start up just fine cold.

[The Aspirator]

Yeah warm idle mine really likes 13-13.5, but cold idle sucks, just tries to die unless I give it a bit of throttle. So maybe it is too rich when cold?

John

[Matt Dupuis]

Looks pretty lean at 1000 RPM. My car doesn't like it that lean at idle, for sure. In fact, nowhere does it like being at 17:1. 16.5 is about the limit for smoothness, and anything over 16:1 is starting to get into pretty lean territory, where you might be losing fuel economy and adding emmissions. I know you and I went over this on MSEFI, but I thought I'd bring it up here again.

Also from 5000-6500, in any load row, you don't change your target AFR at all. That means you could set the last bin to 5000 and use the other two somewhere you need it, like around 2400-3100 for lean cruising. Same goes for 1000-3000 RPM, and your 225 and 250 rows - you could stop the table at 225 and use one more row for off-boost cruising, where I suspect you probably spend 80% of your time or more.

Sorry, nothing against your choices... I just see a table so heavily biased towards top end load and RPM on a car that's supposedly used on the street and I wonder why all that space is wasted on an area that: a) doesn't change very much; and b) rarely gets used.

I, personally, would set them up something like this:

200 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0
150 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.0 12.0
100 13.0 13.0 13.0 13.0 13.0 13.0 13.0 12.5 12.5 12.5
90 13.5 13.5 13.5 13.5 13.5 13.5 13.5 13.0 13.0 13.0
80 14.0 14.0 14.0 14.7 16.0 16.0 14.7 14.2 14.0 13.8
70 14.0 14.7 14.7 14.7 16.0 16.0 14.7 14.7 14.4 14.0
60 14.0 14.7 14.7 14.7 16.0 16.0 15.2 15.2 14.7 14.7
50 13.7 15.0 15.0 15.0 14.7 14.7 14.7 14.7 14.7 14.7
1000 1300 1800 2200 2400 3000 3300 3800 4500 5000

Remember, once you leave the edge of the table, it carries the last value, so everything above 200 kPa will be at 12.0:1, and everything above 5000 RPM would be the same AFR as it was at 5000. At least that's the way it works with the VE table, so I assume that's the way it works with the AFR table.

Also remember, your VE table must follow your AFR table, in it's current iteration. By that I mean you must set up your VE table so that at each of these rows/columns your engine would naturally run at close to these AFRs anyway without EGO correction. That's why I don't like the current setup, and why I'm hoping James changes it.

Until he does, I just set my VE table to do what I want it to do, and turn off my EGO correction. I'm not going to try implementing the target AFR table at all.

[the poi]

good points matt, if i were paying attention i may have even caught the redundancy myself...but i doubt it the egocorr shuts down at 1300 rpm.... but ill richen up those lower points. Ill see if this thing is worth its mustard

[kyle242gt]

Hey guys, funny you should ask, I was just working on mine... But before I get into it, let me share an interesting tuning method I'm trying out. I use an egoCorrGauge in Spark Tuning instead of an AFRgauge. With the EGOcorr intervals as 32 ign cycles 2% changes per step, I can see the EGOcorr start at 100% with any rpm/map bin. If you hold it steady, it will cycle to 102%, then 104%, then 106%, or 98-96-94. If the EGOcorr goes up, richen that bin and those around it a tick or two. If EGO goes down, lean it a bit. A shotgun approach works really nicely assuming you have a reasonable map to start with. I also find it a lot easier than reading the AFR, remembering what I'm aiming for at that rpm/map, and adjusting the VE accordingly... maybe I'm slow, but by the time I remember which way I want to go, I'm usually on to another bin. Much easier to see if you're consistently getting 100+% EGOcorr as you drive around.

Another thought I had was making your AFR targets leaner than your map. As you zip up through the rev range, it'll use the rich map VE's and you'll get more power and smoother acceleration. But if you're accelerating more slowly, the AFR targets take over as you slowly move through the bins. I'm not sure this is really ideal, but an interesting opportunity.

Anyway! Here's what I'm running.
180 12.5 across the board
130 13.5 across the board
110 14.0 14.0 14.0 14.7 14.7 14.7 14.7 14.7
100 15.0 15.0 16.0 16.5 16.5 15.5 15.5 15.5
075 16.0 16.0 16.5 16.5 16.0 16.0 16.0 16.0
050 16.0 16.0 17.0 17.0 17.0 17.0 17.0 17.0
040 16.0 16.0 17.5 17.5 17.5 17.5 17.5 17.5
020 16.5 18.5 19.0 19.0 19.0 19.0 19.0 19.0
__ 1500 2000 2500 3000 3500 4500 5500 6000

My car runs great at 16, not so well at 17, so just this evening I started aiming for 16 instead of 17 under any kind of load (75Kpa). At 50, it's barely creeping along, so 17 should be fine, likewise for 40 and 20. My car seems to lurch and lug a bit at the 2000 rpm area, so low-load is set to be a little richer. Cruising speed is at 3000 so I aim to keep it lean. I frequently see 100Kpa on the freeway as the turbo is starting to spool, so a lean spot there as well. I'm not boosting a whole lot, but for those long 3rd gear pulls, my numbers seem to be working well.

The AFR targets are too damn cool.

Other points - Matt addressed the overlean condition, and I'm with him on it... I'm richening things up as I go, but I want to err on the lean side.

Cold start and cold running... 11:1 is way too rich, fix that up, yo! I managed to get much improved cold start (fires almost instantly and idles rock steady from the first rev) by playing with the startup pulsewidths. Afterstart enrichment is key, and with MSnS-E you can set it to seconds instead of ignition cycles.

[The Aspirator]

Thanks Kyle, Matt, and Poi (okay, Chris, but you're Poi to me). This is helping me out! Which reminds me I've still got to read Matt's article about using MStweak....

Warmup stuff:
So let me see if I get this straight. I was under the impression that you wanted it richer during warmup, hence my rich conditions. BUT, is it just that the car requires more fuel while cold to achieve the same AFR as when warm? So if I'm idling at 13.5 when warm, I want it to idle at 13.5 when cold too? But it'll take more fuel to do so (hence the warmup and afterstart enrichments)???

Also, what exactly does overrun mean? Poi mentioned it above, and the other guy asked about fuel cut, so I wanted to know.

John

[Morten VJ]

13.5 AFR at idle sounds preatty ritch to me.
My setting is currently around 14.1 AFR at 900 rpm.
I dont think you can target a specifik AFR ratio when cold.
Basic you give it what it wants, And it's yousally wery ritch, because of fueldropuot, incomplete combustion, stiff oil, and other tings.
Overrun is when the engine is driven by the weels in gear not the fuel and air miksture.
Fuel cut is simply cutting off the fuel to the engine when on overrun.
About the stumble vhen getting out of overrun, i had them to. I removed them by setting my ve map ritcher at 40 kpa like 12-13 AFR below 2000 rpm.
My current overrun settings is enable belov 28 kpa and above 1500 rpm.
Otherwise i get som stumbeling driving dovnhill at wery low speeds.

Just my 0.50 kr

Morten

[The Aspirator]

Originally Posted by Morten VJ

Overrun is when the engine is driven by the weels in gear not the fuel and air miksture.

Suprisingly, I didn't know that. At least I didn't know it was called that. Makes tons of sense, thanks for explaining it to me!

About the stumble vhen getting out of overrun, i had them to. I removed them by setting my ve map ritcher at 40 kpa like 12-13 AFR below 2000 rpm.
My current overrun settings is enable belov 28 kpa and above 1500 rpm.
Otherwise i get som stumbeling driving dovnhill at wery low speeds.
Morten

Good advice, I'll definately try that next time I tune my car.

Just my 0.50 kr

[Matt Dupuis]

Originally Posted by kyle242GT

let me share an interesting tuning method I'm trying out

That's similar to what I had in mind for my next go-round, except that I'd be datalogging and I'd filter out RPM and MAP bins I'm looking for and let Excel average the EGOcorr% for me, so I know how much I have to richen or lean the VE table to achieve the AFR I'm looking for. Very similar to MST3K, except it's not looking for crossover points and discarding all the rest of the information. I really prefer tuning while parked, and keeping my eyes on the road when I'm driving...

I can share my little excel file so that you can import your datalogs, if you like.

[the poi]

Originally Posted by Matt Dupuis

That's similar to what I had in mind for my next go-round, except that I'd be datalogging and I'd filter out RPM and MAP bins I'm looking for and let Excel average the EGOcorr% for me, so I know how much I have to richen or lean the VE table to achieve the AFR I'm looking for. Very similar to MST3K, except it's not looking for crossover points and discarding all the rest of the information. I really prefer tuning while parked, and keeping my eyes on the road when I'm driving...

I can share my little excel file so that you can import your datalogs, if you like.

please do matt! I ahve in fact ben waiting a day to ask you to do just that Im essentially back to tuning form scratch now, with the new cam and new injectors... really ahve to do some hardcore tunign I think before some AFR table magic will work, I'm runnign 10.5-11 AFR's pretty much everywhere

[kyle242gt]

Hi Matt - that would be cool, please post a link, I imagine lots of us would like that.

In other news, I've rearranged my target AFR's a we bit, might as well share for posterity.

Most guys seem to err on the rich side, I'm erring on the lean side

180 12.5 across the board
130 13.5 across the board
110 14.0 14.0 14.0 14.7 14.7 14.7 14.7 14.7
100 15.0 15.0 15.5 16.0 16.0 16.0 16.0 16.0
075 16.0 16.0 16.0 16.0 16.0 16.0 16.0 16.0
050 16.0 16.0 16.5 16.5 17.0 17.0 17.0 17.0
040 16.0 16.0 16.5 17.0 17.5 17.5 17.5 17.5
020 16.5 18.5 19.0 19.0 19.0 19.0 19.0 19.0
__ 1500 2000 2500 3000 3500 4500 5500 6000

More or less, everywhere marked in bold was richened a half-point. The jury's still out on if that's rich enough, only just now getting the VE table set to match.

But it's awesome so far, some of the points are just nailed down. Driving around, the EGOcorrgauge shows 100-102-100-98-100-102-100-98. Love it. From what I can see 1VE is about 2% on the EGOcorrgauge, at least with my setup.

It's also worth pointing out that it's very helpful to have changes in your AFR targets correspond with your VE bins. pretty tough to tune 100Kpa=15.0, 110Kpa=14.7. 130Kpa=13.5 without a VE map at 110Kpa.

I think it also bears mentioning that there's really not much use in the target AFR's at the high RPM end of things; regardless of what you really want there, you don't spend enough time at 5,500 RPM to let MS make its adjustments. I get the feeling that you could probably safely chop off the highest three and (lowest one) RPM bins and thin out some of the VE table's middle VE values (ie, keep 50-60-70-80 and dump 65 and 75, etc) to get to an 8x8 target AFR table that matches the VE bins.

Sorry to go on so long, but I really the target AFR's. I almost (gasp, sacrelige) like it more than the 12x12 maps.

On the subject of cold start and drivability, set the cranking PW's so it fires up almost instantly, then set the afterstart enrichment so that it stays running smoothly, then set the warmup enrichments to get away from lugging/lurching, then set the cold accel enrichments to get smooth acceleration. Keep an eye on the WB and make sure you're not running to rich to fire; I'd aim for 13+ as much as possible. Here's mine, but bear in mind that "cold" here means about 40F.

*edit - you also need to go into Code Config | Advanced code options and change After Start Enrich Counter to "Sec" - otherwise it defaults to ignition cycles, which ain't enough time. about one second if I do my math right.

[Matt Dupuis]

I won't be able to post a link to my little excel file until later tonight, but you can easily duplicate what I did without seeing it if you think about it a little.

It's really quick and dirty - nothing fancy at all, and it's such a memory hog that occasionally it hangs up for a few minutes sorting through the data. I'd really prefer to have someone do something like MST3K, except instead of going through the hassle of telling me what VEs I want, I'd rather it tell me exactly what AFR I'm running at which point.

That's really what I did that excel file for in the first place - so I could choose an RPM vs load and it would tell me what AFR I averaged over that datalog. It could easily be changed to return an average on EGOcorr% or EGT or whatever else you want from the datalog.

[the poi]

woo, too much good stuff in here. I think im just gonna knock back my reqfuel until the majority of the map is correct, and then fix the idle (again ). What injectors is everyone running? I went from greentops to CFI's and the idle behavior is extremely differnt, my idle VE points are quite high compared to the rest of the map...nothing that cant be tuned out, jsut curious if other peopel had similar issues

[The Aspirator]

Matt, I too would like to see that Excel file!

Kyle, thanks for the tips on warmup tuning, I'll get around to it eventually and report back. It's probably stupid easy to do, but I haven't even touched Megasquirt in the last 500 miles.

Poi, I'm using the "400" CFI injectors with a 3bar FPR. From memory I idle at about 40-45kpa at 900-1000rpm. Months ago I remember I used to idle at 30-35kPa, I'm not sure what changed. Cam stayed the same, pretty much only bigger turbo and injectors. Ohh and 405 head, maybe that has something to do with it. I could probably get it to suck more at idle than 45, but I haven't really tried that hard. It's smooth enough for now.

John

[Matt Dupuis]

Originally Posted by the poi

woo, too much good stuff in here. I think im just gonna knock back my reqfuel until the majority of the map is correct, and then fix the idle (again ). What injectors is everyone running? I went from greentops to CFI's and the idle behavior is extremely differnt, my idle VE points are quite high compared to the rest of the map...nothing that cant be tuned out, jsut curious if other peopel had similar issues

Your CFIs are probably taking longer to open than the greentops, necessitating a higher VE at low pulsewidths.

[the poi]

Originally Posted by Matt Dupuis

Your CFIs are probably taking longer to open than the greentops, necessitating a higher VE at low pulsewidths.

aye, tahts what I figured. I set the openign time to 1.3ms (great error message when setting it above that, heh) and it has seemed to flatten out clsoer to where Id expect it to be

[Matt Dupuis]

http://members.shaw.ca/UglyDuck3/ms/

It's in there. I don't have time to do a write-up on it, but if you cut and paste one of your datalogs into Sheet 2, you should be able to enter stuff into sheet 1 and pull out AFRs, IF you're using a Techedge WBO2, AND you're using the WBLIN.

On sheet 3 is the filter command - it's really crude, I told you that already. If you want EGOcorr or whatever, change the appropriate column.

Gotta go - off to work. More later.

[Paul_VR6]

Originally Posted by kyle242GT

Most guys seem to err on the rich side, I'm erring on the lean side

180 12.5 across the board
130 13.5 across the board
110 14.0 14.0 14.0 14.7 14.7 14.7 14.7 14.7
100 15.0 15.0 15.5 16.0 16.0 16.0 16.0 16.0
075 16.0 16.0 16.0 16.0 16.0 16.0 16.0 16.0
050 16.0 16.0 16.5 16.5 17.0 17.0 17.0 17.0
040 16.0 16.0 16.5 17.0 17.5 17.5 17.5 17.5
020 16.5 18.5 19.0 19.0 19.0 19.0 19.0 19.0
__ 1500 2000 2500 3000 3500 4500 5500 6000

More or less, everywhere marked in bold was richened a half-point. The jury's still out on if that's rich enough, only just now getting the VE table set to match.

I would still richen up the bins from about 75kpa-110kpa, at least to 13.5:1. If you leave it that lean around there, your asking for lean onset knock if you try and run any amount of timing there. Shouldn't effect your off boost mileage much either at that MAP value unless you're running a REALLY small turbo.

FWIW, I wouldn't even run an NA car at 15.5-16:1 at 100kpa.. around stoich you're asking for trouble, so set it at least a little richer then that.

Have you checked your plugs lately for signs of detonation? What's your spark table look like?

[kyle242gt]

Hi Paul, thanks for the feedback.

Here's my spark map


Can't run more than 35 at any kind of load, can't say why for sure, but the car just bucks like a muhfuh. And looking at it offline, I'm tempted to toss in a few more degrees at cruise (2500-3500 50-80Kpa)

at 75 Kpa, I'm crusing on the freeway, very light load, no reason to dump extra fuel in... and it's very easy to get to 100Kpa because the turbo's all spooled up (and ready to blow), so it's easy to see 100Kpa at very light load as well. I could probably stand to move the 3500RPM+ bins to stoich or beyond, but if the engine's under that kind of load, it's well into boost.

I'm trying to tune for economy, which is ironic since my speedo cable is busted but that's also why I only want to hit stoich at 110Kpa (1.5PSI). You'll see that things richen dramatically past that point, both in the interest of not-blowing-sh!t-up and making max power.

If I was NA, I'd be going for 13.5 at 100Kpa, but I think 100Kpa means totally different things to a NA car versis a boosted one. Am I wrong?

What's "lean onset knock"? I'd guess knocking and hestitating from an overlean/overhot/overadvanced mixture? If so, that's why I've gone richer at the bold AFR bins.

*edit - haven't pulled the plugs lately, haven't opened the hood lately but I've been meaning to check... I sure am running this thing crazy lean...

[740Weapon]

"If I was NA, I'd be going for 13.5 at 100Kpa, but I think 100Kpa means totally different things to a NA car versis a boosted one. Am I wrong? "

its only different if the compression is different as far as i can see