Datalogging and data analysis - How do you get the most out of your datalogs?
I'd like to start a discussion of data analysis - how you take the datalogs from whatever engine management system you're using and turn all that data into information that you can use to correct / improve your tune. I'm hoping some of the experienced tuners (professional or amateur) can chime in with their methodology for analyzing datalogs, tips or tricks they use to help them pull the pertinent information out of the thousands and thousands of lines of data, etc.
I've had a Tweecer RT on my '89 for years, but have never really taught myself to do much actual tuning. I've used the datalogging feature on many occasions, but I don't feel like I'm able to effectively turn those datalogs into useful updates to the tune. I have EEC Analyzer, and I've used the functions there, but I haven't gotten much out of that - seems like the changes that it makes are pretty small, which would lead me to believe I'm not feeding it the right info / good enough data.
In a thread a month or so ago, someone commented about having 4-1/2 minutes of datalogging, and was told that wasn't enough for a tuner to do anything with. So, how much data is enough? I'm sure that varies depending on where you are in the tuning process (just starting vs working on fine tuning a "mature" tune). How do you go about determining how much data is "enough" for those different scenarios? And how does one ensure that you get the right kind of data as you're driving (hitting the right load or the rights part of the MAF curve or whatever)?
Once you have the datalog, how do you go about processing the data to pull out what you need? When I drive around and take a ~20min datalog with the TweecerRT, that results in about 14,000 lines of data. It's a lot to look at, and I kinda get lost.
- If I put the data into Excel, there are a variety of ways I can use Conditional Formatting to highlight data - turn all the OL lines one color, CL lines another color; if MAF is > some value, turn it a color, etc etc. But even if I do that, I'm still left with tens of thousands of lines in the spreadsheet, so it's not easy to see trends at a glance. So, if you're looking at a spreadsheet, what tools do you use to pull out the data you're trying to focus on?
- If I put the data into Excel and graph it, I end up with a massive graph (again, tens of thousands of data point), which makes it pretty much impossible to pull out small changes or short duration events. So, if you graph the data, how you do it in a manner that allows you to see what you're trying to find?
For those of you who are experienced and good at doing this, these are probably stupid questions. But I have a feeling that I'm not alone when it comes to figuring out how to effectively use datalogging to help me improve my tune, so I'm hoping that some discussion here can help us all make the most of whatever engine management we're using.
'89 GT convertible, N/A 357W, MM front susp w/425# coil-overs and Koni D/As, MM TA/PB rear setup (Koni Yellows, 390-430# springs), Stoptech 332mm / 12" Baers, MM 6 point rollbar, Maier 1.5" flared fenders & quarters, 18x9.5" front/18x10.5" rear Enkei RPF-1s (street), 18x10" CCW C-10s (track), etc...