loscooby

Hi !

I am trying to build myself a car-PC that can among other stuff display engine params and fault codes.
I do not yet know enough about all the parameters that are available through the OBDII-protocol of my STI 8.

I have not found any parameters that has to do with turbo boost pressure apart from a parameterPID 0B) 'Intake Manifold Absolute Pressure' meassured in kPaA.

Does anybody know if this is the parameter or if the turbo boost is available when using OBDII?

/L-O

dnb

Manifold pressure is the same as boost pressure!!
It's just that it's measured relative to a vacuum.

If you read atmosperic pressure at the same time, and subtract it from manifold pressure, then you get "boost pressure"

dnb

I'd be interested in what you know about ODBII. I only have experience with older cars and the Subaru "select protocol"

loscooby

Hi,

I am mearly a beginner in terms of OBDII but I have at least gotten a OBD2-freeware(scantool) to actually communicate with my STI8s ECU and I have also gotten my on VB-code to communicate with the ECU.

There is quite alot of info on the net regarding the OBDII-protocol and also hardware to connect a laptop to the diagnostics port. Everything from very expensive pro-tools to the simple tools.
My choice was a board based on the Elmscan-chip which lets you communicate via the RS232-port at 9600Baud.
The chip then converts and transfers the cleartext OBD2 commands.

The protocol is fairly well documented since many cars must conform to the standard in order for workshops to diagnose a car without actually being a brand-specific workshop.

All car makers that conforms to the OBD2-std must implement support for basic engine parameters like vehicle speed, RPM etc and also some of the error codes in the OBDII-spec.
There is also a vendor-specific part of the protocol that specifies vehicle specific errorcodes and engine params.

Hope it gives you some inf, at least the links should...

/L-O
A few links...

http://www.obd-2.com
http://obddiagnostics.com/obdinfo/info.html
http://http://www.scantool.net
http://www.elmelectronics.com

dnb

Thanks. I'll have a play with my mother-in-law's new car when she's not looking

greasemonkey

dnb - sorry for hijacking the thread, but I'm currently in the very early stages of working out the Select/OBD protocols of the MY99/00 ECU's. Do you have any links or other sources of reference that could save me some of the guesswork? Thanks!