Data Log Analysis - Motorgen - Automotive Events, Meets, Cruises and Forums

Vettezuki · 03-30-2011, 12:59 AM

So I got my cheapy ELM327 BlueTooth ODBII connector and (free) Android Torque app. Logged my trip to the gym tonight and it seemed to work out fine. See attached. Two things strike me, one of them makes sense.

One, holy shit coolant temp spikes like a mofo when you shutoff. A nearly instant 10 degree carry over is pretty intense.

Secondly, the MAF seems to be reading some odd seuqences, but I suppose it could be related to throttle position, which I didn't log. Check it out let me know what you think.

Shaolin Crane · 03-30-2011, 09:49 AM

How confident are you in the accuracy of a free app?

SkunkLookingCar · 03-30-2011, 10:20 AM

I didn't see a time scale or a sample rate so it's hard to tell what kind of time frame we are dealing with. I'm guessing the temperture spike is from heat soak after the water stops circulating the coolant but I can't tell how fast it is spiking. The MAF readings seemed to have a fairly linear relationship with engine load. At the couple of points I looked at it looked like every ~10% of engine load correlated to about ~30g/sec more maf reading.

SkunkLookingCar · 03-30-2011, 10:42 AM

I just did the math in Excel and it works out to 3.00g/s for every 1% of engine load over the 807 datapoints where the car is running.

Vettezuki · 03-30-2011, 12:13 PM

Quote:

Originally Posted by Shaolin Crane

How confident are you in the accuracy of a free app?

Now days, quite. Plus, this is just reading data from the ECU and logging it.

Vettezuki · 03-30-2011, 12:16 PM

Quote:

Originally Posted by SkunkLookingCar

I didn't see a time scale or a sample rate so it's hard to tell what kind of time frame we are dealing with. I'm guessing the temperture spike is from heat soak after the water stops circulating the coolant but I can't tell how fast it is spiking. The MAF readings seemed to have a fairly linear relationship with engine load. At the couple of points I looked at it looked like every ~10% of engine load correlated to about ~30g/sec more maf reading.

That's kinda what I figr'd, it makes sense with load. The device time gives scale but I'm not sure what that is. If I turn GPS on it gives clock time as well.

blackax · 03-30-2011, 01:19 PM

I've always have had issues with Torque and they way it exports the cvs files. It doesn't seem to put the right data in the right column. I was able to fix it by hand but still a pain.

Still one of the best apps out there

Ryridesmotox · 04-01-2011, 01:32 AM

If you need to data log something let me know. I have HP tuners and you can borrow my laptop on the next meet at GMR. It has a real badass readout and can be customized for literally any readings you want. MAF (HZ), MAP, engine load, rpm, coolant, speed, baro pressure, timing, wideband sensors, cam angles (for my variable valve timing), injectors... basically if your car's ecu controls or records it I can log it on HP. And it can clear codes and stuff... any chevy, dodge, or ford.