MicroSquirt.com read only forum (Jan.15,2018)

MS2/v3, code 2.33, megatune 717, LC-1 wbo2

I'm glad i got it all together and it works, but to the point.

autotune got my ve table setup, car runs smooth, but ve table tooks bad.

generally speaking, there are suddent spikes and dips in the ve table, some values of 7-8%.
as I said, car suns smooth in that area, but I would like to know whether it is normal ?

secondly, with the wideband sensor, which areas of the tale can be tuned safetly with autotune function ? can I tuns with wbo as low as 30kpa ? (engine idles ~35kpa, cruise 40-50 kpa) ? can I tune low rpm regions, such as 1200-2000rpm (low speed cruise) ? what about other areas ? or maby which areas are not recommended to tune by autotune ?

My wbo readout is not very stable. at some points ir varies +-0.2 or 0.3, but at some others as much as +-1 or 1.5. (all steady engine rpm/load, ego correction authority=10%) LC-1 has a function of producting the output averaged over 1 second. is it a good idea to use it (havent tried it yet). all tho at stable speeds it should be great, but on sudden moves it might be bad, i suppose. anybody can comment on that ?

I'm very happy it all works, but whenever I try to adjust ve table manually (i'm just trying to smooth it out few bins at a time), it produces worse results, misfires, jerkiness, etc.

see attached datalog for wobbly aft readings (and my rpm spike at 4.5krpm, which I still have to trace).

Thanks in advance.

mops wrote:autotune got my ve table setup, car runs smooth, but ve table tooks bad.

Well, tuning an engine is definitely not about making the VE table look pretty, it's about doing what the engine wants. If the table is lumpy and bumpy, because of resonance effects and such, that's normal. Artificially smoothing it out just to make it aesthetically pleasing is definitely not the thing to do.

secondly, with the wideband sensor, which areas of the tale can be tuned safetly with autotune function ?

This is all boils down to knowing what the correct AFR is for various running conditions. If you don't know that the idle wants to be 12.2:1, then how could you use auto-tune to tell it to "fix things?" Certain parts of the table are "safe" to tune any way you like, but unless you actually know what works best, you are still guessing. (This is the big reason I don't like auto-tuning algorithms, they assume that you know proper AFRs and that usually isn't the case.)

For example, if I want to tune for maximum cruise MPG, what is the correct AFR? I have no idea, but I do know that it is the leanest I can go before I start getting lean misfires. So, in this case the correct AFR is dictated by the power delivery capacity of my ignition, not anything to do with fuel...

Auto-tune is good for getting a rough table, but if you want optimal tune of any aspect (idle quality, cruise MPG, maximum power), then you'll need to do manual tweaking, paying attention to a lot more than the output of that lambda gauge.

Eric