richmc

The ECU is working at a much faster rate than the OBDII, so does anyone do a unit to tap into the ECU data? The guys that make aftermarket ECUs would know.

EDIT- you are going to need at least 0.1s resolution.

lovegroova

Just ordered an Scan Tool LX and will report back!

chrispayze

Thanks Mark, that would indicate approx 4Hz from the obd port. Groova, let me know how you get on, that's the one I'd pretty much narrowed it down to. I spose if I just logged revs from the ecu, and GPS speed & acceleration from the phone, it could be enough take a rev counter on track day videos just about worthwhile at 4Hz.

lovegroova

Get a 10 Hz GPS unit (I use a QStarz 818XT) and then you get good speed readings at least (and they are more accurate than the speedo of course)

http://www.amazon.co.uk/Qstarz-BT-Q8.../dp/B005GDIPMG

chrispayze

Yup, that was another plan of mine, although I'm not sure (and can't find out anywhere) what the update rate is on my new S5. Wanted to date check it wasn't more than 1Hz before I stuck a 10Hz unit on my Xmas list!

mdb_75

I use a Qstarz BT-Q818XT and a cheap ELM 327 adaptor for my logging. I think my rpm and throttle position update rate is fine. Does it look ok?

Have a look HERE

lovegroova

Looks much better than mine

chrispayze

I'm wondering if that's an update rate or smoothing that's making it smooth? But it does look decent. Perhaps the Chinese copies vary a lot (wouldn't be a surprise) and you got a decent one. If so, Lovegroova's should work fine.

mdb_75

What apps are you using, maybe that makes a difference? I use Race Chrono.

lovegroova

Mine was Torque for those.