Gopoint BT1 OBD reader

[themanalive]

I have a 2008 SV 125 with the Sigma engine and I recently bought an OBD reader, a Gopoint BT1 with the intention of using it at track with Harry's Laptimer. The Gopoint is supposed to work via bluetooth and an IOS device.

I've tried it on the Caterham with no luck. I gave it a go on the office car and it connected no problem, which leads me to think its the car not the device! Has anyone managed to get an OBD reader working with a Caterham? I thought it should be no problem at all.


Thanks

[LostCroc]

While you have a J1962 plug to connect to, Caterham ECUs do not output an OBDII signal. So it is not your reader but the car.

Not sure what ECU is on a Sigmas? On the MBE ECUs the signal produced through the J1962 plug is CAN so you can tap into it wire by wire and read the signal but an OBDII reader will not do that. I have a wiring diagram of the various wire signals in the plug but that is at home in NYC and I am in London for a while. Maybe try looking at the SBD website they have some good technical information:
http://www.sbdev.co.uk/Engine_Management_Systems/E...

[themanalive]

Thats really annoying. I was hoping to use it with Harry's Laptimer at trackdays. So if there is no OBD II signal, I take it there is no simple easy way to get the speed/rev etc data other than as you suggest and having to get very technical.

poo.

[LostCroc]

If you wanted OBDII data then no. However, I thought Harry's did provide you speed data through phone GPS? If not then look at a free app called Vidometer. This takes video with speed and G force data overlaid but does not do lap times.

[themanalive]

It does, but it has not been very accurate. I have a camera as well so can clearly see the speedo showing the correct speed and the Laptimer showing something different.

I used to use an old Nokia with Racechrono which seemed to be much better in terms of accuracy.

When I saw that Harry's supported the bluetooth Gopoint OBD reader I thought I had done the research and had seen posts about using OBD readers on a caterham (obviously got that wrong). I thought it would be a good way to get the accurate speed and also RPM into the data.

Oh well.

[themanalive]

I have been looking back through my searches of Blatchat about OBDII and it does seem a mixed picture. I did find the thread that actually put me on to Bluetooth dongles:

http://www.blatchat.com/t.asp?id=211081


Is that you LostCroc in the last post? Did you try and then find out it does not work?

[LostCroc]

themanalive said:

It does, but it has not been very accurate. I have a camera as well so can clearly see the speedo showing the correct speed and the Laptimer showing something different.

LOL. The speedo on a Caterham is not accurate either. I have a GPS sensor used on the professional bike racing teams and it shows my speedo off by 10mph in a track environment. For example at an indicated 132-133mph on the speedo(on video), GPS has me at 121mph logged. I think I trust the GPS in this case because it fixes to 8-10 satellites.

That said, the GPS in an iPhone is notoriously suspect as you rightly point out. Not much you can do in this instance. There was that fun night where a group of us experimented with Vidometer in a bar and I managed to achieve 2mph leaning against the bar with a pint in hand!

Does Racechrono still produce its iPhone app?

themanalive said:

I have been looking back through my searches of Blatchat about OBDII and it does seem a mixed picture. I did find the thread that actually put me on to Bluetooth dongles:
http://www.blatchat.com/t.asp?id=211081
Is that you LostCroc in the last post? Did you try and then find out it does not work?

I am famous! Yes I tried and failed. It does not work even when rewiring the J1962 plug to be tapped into. A friend in NYC managed to rewire the plug to match into an AIM data logger. The signal is CAN and is read perfectly by the AIM unit. However, we never could get the bluetooth unit to do the same as it is not outputting as OBDII. It does power up and transmit but my logger was not recognizing the signals coming in as OBDII and could not log them.

The other issue with OBDII that we discovered is that it is too slow. Without getting all techie, OBDII/CAN transmits sequential channels from the MBE ECU. So each data channel waits its turn to report. From the AIM installation we discovered speed might be delayed by 1/3rd to 1/2 a second depending on the number of channels being reported ahead of the speed channel. A speedo is more real time in this case than the OBDII readout. If you do the math, at speed you can cover a lot of distance in 1/2 second and on video this will show up as you accelerating with the data whereas on the video image you are really braking.

So your most accurate option is to really tap directly into the data channels you want for tach, temps, etc. For speed a proper GPS unit is needed.

Does Harry's allow you to bluetooth a external GPS sender? I have used one of these and it works great bluetoothing into the Racechrono Touchscreen:
http://www.pocketgpsworld.com/qstarz-btq818-gps-re...

Where you are heading is something beyond the iPhone but not as involved as a Vbox. I experimented with these two:
http://www.qstarz.com/Products/GPS%20Products/LT-Q...
and
http://racechronosystems.com/lap_timers.shtml

While both have internal GPS it is not accurate hence the external GPS bluetoothed. Both output data on a CSV spreadsheet and you then overlay it onto the video yourself (RaceRender). Racechrono Touchscreen was far and away the best - easy to use, easy to set up a new track, can be used with gloves on, discreet for non-timing events. Downside is that it is pricey because you also have to buy a camera.