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Lamda lag factoring

Road Tuning

Discussion and questions related to the course Road Tuning


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Hi my question is on smoothing with my ecu i have spent a lot of time making sure i don't have voltage noise in the system but i'd like to know how to confirm that for sure, but that's a side note. the main concern is i see a Lamda difference in my data logs of .934 .968 spikes when i'm centered in the cell (Haven't doneany steady state tuning yet it's just been auto tuned) that's is with NO smoothing how do you know you have the smoothing set right and its not to much filtering on AFR?.. My ecu is Megasquirit.

Thanks

Change your commanded lambda while driving and then change it back. That will you a good idea of how long from a change in fuel output to its seen by the o2 sensor. Also note this lag factor really is more then one value, its depends on airflow and load.

I've had very little experience with megasquirt at this point so I can't answer your question specifically unfortunately. It's pretty typical to see the lambda trace jump around slightly. In some ECUs you can filter or smooth this to give a more stable trace while others don't offer this option. It's usually relatively easy to mentally smooth or average the lambda trace in your head though and this is the only option in some ECUs.

If you want to try smoothing the signal, I'd suggest adding a little filtering/smoothing if the signal is quite erratic but the danger of doing so is that the smoothing will also slow the response of the sensor reading so you want to use as little smoothing as possible.

Hopefully that info is of some use to you on the Megasquirt platform.

yes that pretty much sums up what i was able to find my self. Thank you!

The smoothing factor on Megasquirt is pretty straight forward.

100% = no smoothing

10% = heavily smoothed (average over the 10 previous reading)

Personally I keep it at 100%.

(BTW, You can smooth the log later on megalogviewer if you want to)

I can help with most any generic Megasquirt question. If you post your data that I can down load, I will show you how to "see"/determine if you have noise issues using MLVHD.

Andy