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Discussion Starter #1
I'm sure someone will've thought about this before...

I've been trying to find out a bit more about using Dataloggers which frequently use a standard OBD2 interface.

Presumably, our old knackers don't have OBD2 - it only became a requirement in European cars in 2000.

However, they clearly use some kind of OBD and have -at least- the diagnostic socket as an interface.

Can this be interrogated using either logger devices or software on a laptop using a specific cable?

Cheers,
Andy
 

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Discussion Starter #3
Yes mate, EOBD (OBDII) was only mandated for european cars post-2001.

The original OBD may be able to provide the things I was looking for like an RPM signal and road speed, but I achieved most of what I needed with a GPS Datalogger (which I still use today).

I was hoping to possibly record data like steering angle, brake pedal pressure and throttle angle too, but that may not be possible with a vehicle based on OBD1. Most of these things are used as inputs for modern stability control, so this data is all easily available on cars like my M3, but not so easily on the M5.

In the end, I decided that I have more significant factors affecting lap times than my inappropriate brake pedal pressure or steering angle, and decided to work on smoothness, lines, and using oversteer to your advantage instead.

What is the device?
 

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Discussion Starter #5
I'll bring it tomorrow (by which what I mean is, I haven't removed it from the M3!).

It's a Pretec BlueGPS Datalogger. It's a little bit wang chung, but seems to work well.

I connect to it by bluetooth to download the logs and it basically just records a trackpoint every second (1Hz).

It's small and light though, and both the battery and memory last 8 hours, which is loads.

I bought it about 18 months ago (oddly enough, just after I posted this thread), and paid £85, it looks like they are now £100 inc vat at this site:

www.globalpositioningsystems.co.uk
 

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It was just the cables and software to attach a PC to the M5. Do you need more than just cables to PC, is there some black box in between to decode.
I want to be able to check codes, re-set fault codes, see live data and possible have the ability to re-map the ecu.
Any advice on equipmemt required and software.
Cheers
 

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AndyE said:
I was hoping to possibly record data like steering angle, brake pedal pressure and throttle angle too, but that may not be possible with a vehicle based on OBD1. Most of these things are used as inputs for modern stability control, so this data is all easily available on cars like my M3, but not so easily on the M5.
At least in the 3.8 almost all of those data (not sure about the brake pressure) is available: Steering angle sensor is used by EDC, throttle angle from the throttle poti (no simple idle/WOT switch in the 3.8), even 3 g-force sensors are available from the EDC - all of the signals can be read out with the proper diagnosis Equipment, unfortunately it is not that simple as it is with OBDII. Maybe it would be even easier to just fit additional sensors, specific to your recording device.

Brgds
Konstantin
 

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Discussion Starter #8
Kons, that makes perfect sense. I decided that I didn't need the data enough to investigate how to interrogate it, but you're quite right.

It would be quite cool to see graphs of steering angle and yaw over a lap of the Ring, for example!

:D
 

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You guys are like psychics honestly:)

I was just trying this yesterday after getting my car back and was going to post about it. I originally bought a carsoft interface from Ebay which supports OBD1 and 2, and attempted to use this last year but didn't get any luck, it requires fairly exact voltages across the K and L lines (which I understand are connections to the diagnostic circuits) I could never achieve these and the device didn't work. I assumed it was faulty and sold it on. Anyway I recently bought an OBD1 device (yes the M5 is OBD1) this is designed to work with an older version of carsoft KDS. However I found out that most likely the original device was not faulty and it is a problem with acheiving the correct voltages across pins 20 and 15 (from memory). If any device is shorting this to ground, the voltage goes below 10.5v and the diagnostic devices don't work. The new device I bought also doesn't work because of this and it actually reports there's a short on the K or L lines and to unplug the diagnostic modules 1 by 1 until the voltage level is acheived (and to replace whichever module is causing the grounding). I unplugged 2 from under the bonnet and 2 from under the back seat in turn, but it didn't affect the voltage across pin 20, it was still too low. Anyone know where the other diagnostic modules are to disconnect that this device might be talking about?

Just for info- the OBD2 device has a serial cable (from PC) to an interface box, to the round connector that plugs in to the socket on your engine.

The OBD1 looks just like a cable, but the round connector incorporates an IC inside so you are not plugging your laptop straight to the car as the voltages are wrong amongst other things.

Andy how comes you are asking? Have I missed something- do you have an M5 again?
-Greg
 

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Discussion Starter #10
madm5 said:
Andy how comes you are asking? Have I missed something- do you have an M5 again?
-Greg
Naa, this is an old thread that's been dragged back up from the depths of October '04.
 

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For all my own personal data logging, I use a 6 or 12 channel pico logger or similar.
I just glue thermocouples around the engine for under hood temps or drill & tap the engine trans & diff drain plugs for a temp sensor to establish bulk oil temps.
Same with water temps utilising top & bottom hose temps.

I do this type of thing as part of my test work anyhow.
Back in 1997, its how I worked out what the Nissans driveline was seeing under hard usage & its subsequent fitment of extra oil coolers.

I even thought about not replaacing the Turbo charger heatshields when they were rebuilt.
Some strategic placement of thermocouples soon put that idea out the window..huge upheat issues.
Eventually it was all wrapped in Thermotec heat management bandage..amazing stuff for the money.

Cheers
Farrell
 
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