What exactly can be done with it? I know the important thing, A/F, requires you to get an analog sensor.

What kind of parameters can we see and are they meaningful to someone that is not a tuner?
What kinds of things do I need to watch out for if I were wanting to check the "health" of the tune?

Are there any resources that explain this stuff specifically to our cars?

 

You could datalog short term and long term fuel trims to see how accurate your tune is at idle/part throttle before your car goes into "open loop", "WOT", or wide open throttle. This is when your car should be at 14.64 air fuels, and your fuel trims will tell you to what percent the Mass Air Flow Transfer Function is off.

So datalogging SHORT TERM FUEL TRIM BANK 1 AND BANK 2 as well as LONG TERM FUEL TRIMS BANK 1 AND BANK 2 would be a great start. Make sure when you choose which PID's you're going to be monitoring, to choose the ones in capital letters.

As well, you could datalog FUEL SOURCE, SPARK SOURCE, SPARK, SPARK ADVANCE, MAF AD COUNTS, AMBIENT TEMP (INTAKE AIR TEMP), ENGINE COOLANT TEMP, RPMS, LOAD, AIR FLOW, TORQUE SOURCE, THROTTLE POSITION, etc.

These are all nice to have. If you end up having an issue, it's easier to narrow down with the more things that you datalog. Again, make sure you use the values in capital letters when selecting PID's. Those ones I said above are all the basic ones to datalog.

Wideband air fuel is always a great help, though. As you mentioned, it takes an analog input OR monitor it with something different. There's nothing wrong with getting a Dynojet Wideband Commander from us and using it to log. Just record, and then go into Livelink and start recording. Just make sure your laptop has a decent amount of memory and a decent processor. Any questions, feel free to call.

Chris Rose
Tillman Speed, Inc.
www.TillmanSpeed.com
610-497-5776

 

Thanks Chris. That is pretty much exactly what I was looking for. I'm highly considering a mail-order tune because of all the good things people are saying about them. It has been around for some time and I've not heard too many bad things.

 

Good info here as well:

http://www.tricktuners.com/advanced_sct_datalogging.htm

John

 

Awesome! Good luck Randy. Try one of our tunes out! You'll be happy!

Chris

 

That guy has some nice writeups explaining things in pretty plain english.
So we can take the fuel trims and multiply by stoich (14.64) and get the AFR. That is the non WOT AFR and basicly the same as using a narrow band gauge. ???

 

Yes, it's like non-WOT air fuel, you take your average fuel trims, and with a little bit of math, you can find out how far out your fuel trims are. That's about it!

Chris Rose
Tillman Speed, Inc.
www.TillmanSpeed.com
610-497-5776

 

Does the same rule (STFT * 14.64) work for WOT runs at the track? Thus making 13.0 AFR about 0.9 based on datalogging parameters? From what I've read is the Long Fuel Trim is the gradual changes while Short Fuel Trim is the immediate changes. This becomes confusing as one document I read said to add 0.5 to the LTFT number and above 1.0 is lean (actual above 0.5 is lean) and for STFT that below 1.0 reading is lean.

If we're multiplying the STFT reading by 14.64 then wouldn't above 1.0 be too lean? (Unless we're talking WOT then above ~0.9 would be lean?)

 

If you datalog fuel trims and go WOT, it will only show you what the COMMANDED air fuel is, and not the actual wideband air fuel ratio.

Our tunes will go to a flat .875 at WOT or 12.81 is what we command. It will not show, however, what you're actually seeing. You'll notice they go perfectly flat.

Remember fuel trim values at part throttle are shown in reverse, so to speak. You have to take the numbers from bank1 and bank2 at their high and low points, add them together, average them (divide by 2) and then you need to take that number and subtract it from 2 to find out the correction factor.

Chris

 

I see. Making a bit more sense now. A few months ago I quickly logged a 0-60 and my "commanded" trims were around 0.87 ... Seeing yours around the same number helps me be slightly less confused about it.

Thanks for the info

Late Edit:
Has anyone logged A/F at WOT on a completely bone-stock s197 GT? Just curious what they were designed to do from the factory (and I don't really feel like re-installing my stock midpipe and intake in the snow to find out )

 

They command .859 which is like 12.58-12.59 air fuel at wot. They usually see as low as 12.3 from what I've seen here.

 

Thanks! I'm hoping the readings I get are accurate. I've considered installing a wideband sensor & gauge, but if these are fairly reliable I can stick with the datalogging.