Sniper_S2K

Hi ,
I few weeks ago i was interested in monitoring various sensors on my S2000 and i didnt have a clue where to start....

ODB-II it stands for "On-board Diagnostic" what is it? Its a standard that manufacturers have adopted to allow fault finding by using debug software using ODB-II protocol. Quite simply it allows you to view what the ECU see's from its sensors.

All cars built since January 1, 1996 have OBD-II systems. Manufacturers started incorporating OBD-II in various models as early as 1994.

There are three basic OBD-II protocols in use, each with minor variations on the communication pattern between the on-board diagnostic computer and the scanner console or tool. While there have been some manufacturer changes between protocols in the past few years, as a rule of thumb, Chrysler products and all European and most Asian imports use ISO 9141 circuitry. GM cars and light trucks use SAE J1850 VPW (Variable Pulse Width Modulation), and Fords use SAE J1850 PWM (Pulse Width Modulation) communication patterns.

All OBD-II cars have a connector located in the passenger compartment easily accessible from the driver's seat. The S2000's is in the pasenger footwell against the
transmission tunnel under the plastic dash.

So what can i do with ODB-II?
well diagnostic readouts can be examined from an ODB-II port with suitable hardware
interface cable and PC or PDA with ODB-II reading software.
The ODB-II port will also allow you to reset the MIL (Malfunction Indicator Light) in English the check engine light when an error occurs.
Its usefull when making changes to your cars standard equipment or diagnosing faults. i.e you can check how that intake is performing or if that thermostat really is opening at low temperature etc.

There are lots of sensors that can be examined but for example
ECT - Engine Coolant Temperature
IAT - Intake Air Temperature
Adv - Spark Advance for number 1 cylinder.
Vss - Vechicle Speed
Rpm - Revs Per Minute

What about those other standards I have seen?
I have seen CAN Bus and Mobydic interfaces what are they?
CAN stands for Controller Area Network. CAN is a new means of communicating with the car for diagnostics used by car manufacturers such as VW, Audi, SEAT, and Skoda. CAN is considerably faster than ISO-9141 (500 kpbs vs. 10.4 kbps).
mOBydic its a device that allows the supporting of nearly all the current flavours of
interfaces under one device. I beleive the software on the PC or PDA has to support mOByDic in order to work however.

Ok down to business how much and exactly what do i need?

Hardware
-----------
Well for a basic setup which is what i have you need a ODB-II interface
I bought an ELM 327 interface for under 30 pounds off ebay. They come
in 9 Pin or USB variety ( Note most modern laptops use USB these days
and have no 9 Pin sockets )
This interface came with a 9 pin cable i could plug into my laptop
You need a way of displaying the data so you will need a PDA or LAPTOP

Note: if you have a PDA and you buy a USB to 9 Pin type converter this
requires a specific driver installation for your device and probably wont
work on your PDA without that driver.

Software
-----------
There is quite a few software programs about to help you read your cars sensors
showing min / max and average some let you log the data and create complex graphs and some even will give you a estimated BHP/Torque readout using car weight , gearing and acceleration.

some programs i have tried are:

scantool.net
Digimoto
PCMSCAN
Scanmaster
Diagnose

These where all PC Laptop based tools i have tried but some of these might
be available for PDA.

I hope this gives you an insight into ODB-II.

Some information was provided by ODB-ii.com

Sniper.


anyone still awake...?

P 1

Yes. Good post.
This is something I've been curious about but never got round to researching.
Thanks for saving me the trouble - I've learnt something tonight

motogp1

excellent

Amuse Boy

Great info. Will you be posting some of your readings withe tool. Would be interesting.

I may also look into getting one of these.

Sniper_S2K

over the next few weeks I will be posting some information i have gathered with this tool

mikey k

Good timing
I'm looking to get this sort of info out of my S before I bolt the Supercharger on.
Have you actually tried this from an S?

Badger

Can't be changed as far as I know.

(well, that showed me)

Bibbs

OBDII just enables you to get all the inputs to the cars ECU. I use the same port with my custom ECL reader (paperclip) to get the diagnostic codes. I know this is also how companies like BMW reset their service lights for example (through their ODBII interface).

You could get an Apexi iMoni and it gives you a reader etc all in one.

or

You can get all the bits and bobs off ebay and wire it up to an old iPaq/Laptop.

I'll be looking at doing something like that, when I get my Zeitronix wired in. So then I'll have the OBD datalogs, and then the external data logs for Wideband 02, EGT, boost etc. Will then allow me to check everything is running okay.

There are issues with some aftermarket ECU's where they are not ODB complient. This is a problem for the Yanks as they need to be by law.

Sniper_S2K

Bibbs,
That APEXI device you mentioned looks like it might be useful
FYI I think the PCMSCAN software supports wideband, might
be worth a look.
I settled on PCMSCAN in the end as the software has a detailed analysis built in plus logging facilities i wanted. Plus the developer seems keen to push the software
further.
Digimoto on the other hand has less detailed readouts has that trick BHP/Torque thingy, Generally is very pretty( ODB bling? ) reminds me of Fast and Furious tbh.

S.

mytse

Interesting.

Thanks for the info Sniper, something I'm very interested in.

Can you post a link of the EML327 product you bought? The ones I've found on ebay are over 60quid, not sure if it's correct.

cheers,