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Old 04-24-2021, 02:40 AM   #608 (permalink)
Ecky
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ND Miata - '15 Mazda MX-5 Special Package
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Quote:
Originally Posted by serialk11r View Post
300mbar? I thought you said 400 before. 300 is so low!

I feel like you need to run more lean. 1.4 lambda would be a good target to aspire to, you may need to warm the air a little to make it work. IIRC you have it at 1.07 closed loop right? Why not open loop? You can run stoich (or buy a wideband w/ emulator) or a little lean in closed loop at the lowest load, rich at max load, and ultra lean in the middle below say 3000rpm.
A few days ago I noted I was cruising around 280mbar at lower speeds, even with my tall gearing. I'm basically at sea level too.

I expect you're right, I could benefit by running much more lean. I can target whatever I want closed loop, but the OEM K series wideband only reads accurately out to maybe 1.25 lambda. The biggest reason I haven't played with it more is that I don't have access to a dyno and haven't been able to squeeze any broad generalizations about ignition timing trends from the tuning groups I follow.

The Insight's original engine leaned out to around 1.65 lambda in closed loop. It appeared to add something like 20-25 degrees of ignition timing vs stoich. It had a high swirl head, indexed plugs, a tiny bore, an offset crank, and very high compression, so combustion speed was very high.

I haven't a clue about where to start my new engine at. If I leaned out to, say, 1.25, would that be perhaps 8 extra degrees of advance? 5? 12? Even if I wanted to trial an error it to a rough ballpark in some of the more commonly used cruising cells with a lot of A-B-A testing, there are literally no flat roads here - nowhere to just hold throttle steady while adjusting timing live.

If you have any suggestions, I'm happy to give them a shot. I can post the ignition maps I use up here for people to look at.
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