Debraj has been developing a project to read the OBD information through CAN bus. His design is based on the dsPIC33FJ128MC802 (3.3V) and MCP2551. He is using a factory stock OBD cable and feeding the data into a jack on the project board. The data is displayed on a 16×4 LCD and includes engine RPM, throttle, vehicle speed, etc.
The description, hardware schematic, software description, code can be found at hobbydebraj website.
Via the contact form.