So I admit it, I’m a geek for data. As an engineer by education, I no longer do technical work in my day to day work.. So this allows me to satisfy that craving

Those who are doing the 1000HP builds and other high-end stuff, all this is probably a big ho-hum.. but for those who are still learning about our cars, this may be helpful..

One of the things that I liked about my UMW tune and logger is the data provided and the full explanation (if one cares to know) behind the data. I’ve learned a ton from analyzing the datalogs and talking to Kevin.

I’ve been using datazap.me to graph data along the x axis for the different parameter.. useful for looking at load, timing, boost, IATs, etc..
Herse an example of injector duty cycle..






I wanted to take it a bit further and started playing with a new graphing tool – MegaLogViewer HD.. I forget what I paid for it, I think about $30..

All these graphs were from datalogs generated from multiple 3rd gear pulls from ~50-100+ in similar conditions.


In addition to the normal data graphing that datazap.me can do, it also can create histograms..

One of the things I learned from Kevin is that the ECU uses a torque model; engine load is the primary element.

Here’s one, showing engine speed on the X axis, Engine Load on the Y axis. The load values are plotted on the table; the darker the shading the more “hits” or higher frequency of that particular data value. I have filtering turned on so I only see data at WOT (Throttle >90) and RPM in a range I want to see,,





Here’s one I’ve been looking at that shows ignition timing vs rpm & load.. When Kevin sends me a new tune I can compare to see what timing has changed vs the other parameters. See how the timing increases as RPMs increase?





Now look at the timing of my old OTS FVD tune.. looks much different, with some random values scattered about, not smooth and linear like Kevin’s.





As you can imagine, there’s a wealth of info to be gleaned.. How about boost vs load?





The tool supports a Z-axis delta, which means it will subtract two values for you and plot them on the “Z” axis.. What would that be useful for, you ask?

Well here’s a log of lambda deltas (Lam1 – Lam2) which is an indicator of O2 sensor responsiveness.. The closer to zero, the better.

This log was taken before I did my wideband O2 sensor change.. check out the rather random dispersion of values – as RPM picks up, I get some decent sized deltas.. again, this is filtered to only look at WOT. There were some variations while load was building.





Now here’s a log I just did a few days ago after my new widebands were installed.. notice how the deltas are all bunched together nice and tight?

This was from a 2007TT with 44K miles and no CEL.. No wonder Kevin tells people to change their O2 sensors at about 10 years..







Finally, have you ever wondered how higher octane fuel effects the engine? Let’s look at the data..

My car was almost empty so I put in 10 gallons of 100 octane unleaded.. Normally I run 93. Ugh this is an expensive test..

Same method for both runs, 3rd gear pulls from 50ish to 100. Plots only look at data at WOT.

I have 3 pairs of plots, KNOCK, timing, and IATs. KNOCK is just a simple SUM of ALL 6 cylinder timing retards at a given instant. 93 octane first, 100 octane 2nd..

Notice how the 100 octane plot has much lower KNOCK values across the rev range..

93 KNOCK





100 KNOCK



Next is the timing, how does this affect timing? Well, because of the lower KNOCK, we have a slight increase in timing across the board..

93 Timing



100 Timing


So this translates to more power, correct? Well, not tonight as I noticed my LOAD was not quite as high with the 100 octane runs.. turns out I had slightly higher IATs this evening (70F vs. 60F OAT) that kept the load down just slightly.. My vbox verified there was no discernible change in my 60-100 times.. I need to repeat the test again when the weather is cooler...

93 IAT



100 IAT


Anyway, I’m still learning but the MegaLogViewer certainly helps to make sense of all those numbers..

Cheers!

 

Man, that's pretty detailed. Nice work though. My data logger is in the mail...

 

Nice tool Seems like that old OTS FVD had a 5 degree timing jump at transition LOAD between 47-48 at 4782 RPM and 4976 RPM... I have never tuned a 996 TT before as I not have software to do it, but I have tuned other cars and have never experienced that big timing jump from a so small jump in load.

 

pretty cool

 

Very nice looks like fun!

 

Interesting that you have so much timing pull on pump gas. That 6.7 60-130 that I ran on pure 93 that has been called overly aggressive by some who can't hit similar numbers had zero pull on any cylinders. Obviously zero timing pull on E85. If you see any significant timing pull on ethanol, you've got some serious issues

 

^ It must have been a really cold day when you did it then, eh?

Here's the latest with a blend of 100 & 93 and IATs between 18-22C. Very low, but not zero..


I don't think ive ever seen ZERO timing pull on ALL cylinders in my logs before..When I logged it stock it was surprising how much timing pull there was..

A 6.7 60-130 is impressive.. I'm working up to those My vboxed 60-100 is 3.29