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-   -   NA car, WOT, how lean is OK (https://www.miataturbo.net/megasquirt-18/na-car-wot-how-lean-ok-27082/)

woodc 10-13-2008 12:40 PM

NA car, WOT, how lean is OK
 
My target AFRs are 12.8-13.1 at 89-101 kPa on my track only NA car.

I see other folks with as high as 14.7 (although they are boosted) at the same map levels?

I am looking for max power thus the 12.8 to 13.1 numbers but am just curious as to how lean is OK before I need to start worrying should it magically start running leaner on track... (and it seems to vary based on what gear I am in and high RPM/high gears have not seen much action on the street).

Matt Cramer 10-13-2008 12:45 PM

Your AFR values sound reasonable to me. I generally don't recommend 14.7:1 at 100 kPa, boosted or not.

apariah 10-18-2008 10:16 AM

Would that mean hitting 17plus while off, or slighty pressing the throttle is really bad. Under load, I'm below 13.4, but often when off throttle (Understandably) or just barely pressing the gas I'm getting 16-17 plus

Arkmage 10-18-2008 10:38 AM


Originally Posted by apariah (Post 321175)
Would that mean hitting 17plus while off, or slighty pressing the throttle is really bad. Under load, I'm below 13.4, but often when off throttle (Understandably) or just barely pressing the gas I'm getting 16-17 plus

that's fine for cruising speeds, it's only heavy throttle and wide open throttle that you need to stay a bit rich at.

johndoe 10-18-2008 12:00 PM

16-17:1 might be ok if you're running the proper advance in those bins, otherwise your EGTs might be a bit high

patsmx5 10-18-2008 12:17 PM

My 99' likes her fuel. I run it 12.5 at lower RPMs at 101kPa and it tapers to 12.0:1 at higher RPMs.

apariah 10-18-2008 01:25 PM

I'm currently stock except for MS, and deleted AFM. I was trying to keep things economical until I get to go turbo.

patsmx5 10-18-2008 01:32 PM

Running 16:1 without an egt gauge to verify safe temps could cause burned valves. 17:1 can cause burned valves with a perfect timing table depending on the engine. 17+ you're gonna break your shit. And rebuilding a head is not exactly economical.

apariah 10-18-2008 02:57 PM

Without someone to drive the car for me is there a way I can adjust fuel to fix this, other than a dyno.

johndoe 10-18-2008 02:57 PM

Megalogviewer

kotomile 10-18-2008 03:08 PM


Originally Posted by johndoe (Post 321232)
Megalogviewer

+1

MLV is your friend.

apariah 10-18-2008 03:35 PM

The analyze feature, thats What I did previously, will using it multiple times refine the settings? I'm still very unclear on manually adjusting the Fuel tables.

johndoe 10-18-2008 04:31 PM

yeah, it takes time. You need to log for at least 20 minutes for it to be worthwile.

apariah 10-18-2008 04:54 PM

Thanks I did that last night, but thought I did it too long for it to be worth while. Does it matter how I drive, lat time I got a alert about using VE for higher RPM tuning.

hustler 10-19-2008 12:10 PM

http://i37.tinypic.com/wlp18x.jpg

apariah 10-19-2008 12:24 PM

Thats not how my table looks

hustler 10-19-2008 12:26 PM


Originally Posted by apariah (Post 321250)
Thanks I did that last night, but thought I did it too long for it to be worth while. Does it matter how I drive, lat time I got a alert about using VE for higher RPM tuning.

lol, I know of 3 MS cars which used 121 for road tuning now, lol.

apariah 10-19-2008 12:45 PM

Their are 3 of us around here now? BTW, my VE Table shows whole numbers nothing with a decimal, or anything that I recognize as a A/F Ratio Hustler where did you go to get that table?

apariah 10-19-2008 01:26 PM

Last night may have been more eye opening than I thought it was, I found out I have to remove my A/F gauge, and I based on what I just read in regards to burnt valves I think I may have to rebuild my head. We noticed last night my car sometimes smells of raw fuel, I thought this was because I was running rich, but I never even considered a burned valve could allow raw fuel into the exhaust. This could suck.

johndoe 10-19-2008 01:47 PM

maybe you should post a screen shot of your AFR table before you get ahead of yourself.


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