Hi all,
I'm new to arduino hacking, and of course I've set myself an ambitious project! I'm eager to learn though!
I drive a 1986 Toyota Celica Supra (note: that's Celica Supra, not Celica OR Supra ;)); its 5M-GE engine has a primitive but quite well designed fuel-injection system, and being a 30-year-old design, is very well understood by now. I was diagnosing some ignition problems using the technical manuals, which list expected resistances and other values for almost every component in the engine bay. This got me thinking - if I can read these values with a multimeter, why not electronically?
I first considered using an RPi for this but I'm starting to think an arduino might be better. Here's the design I'm thinking of:
-Read analogue values from several sensors in the engine bay (air temperature, coolant temperature, oil pressure, airflow, battery voltage, intake O2, exhaust O2) by tapping the lines to the ECU, and digital from the dash cluster (RPM, speed)
-Hack into the car's wonderful digital dashboard and hijack borrow the 3-digit 7-segment digital speedometer VFD to display the value in the correct units
-Have some kind of pushbutton to enter diagnostic mode and change the displayed value
-Hopefully find a way to quickly enable the ECU's integrated diagnostic system (blink codes), and display the code on the VFD
Obviously I'll have to do a lot of research into how to convert the units and such, but I believe this is quite doable and would transfer well to other cars without OBD. I had a look around the forums and didn't find much about car diagnostics, and most of those involved OBD. What I want is a seamless integration with the car, so nobody notices it's there.
The arduino appeals for a few reasons:
-Boot-up times - looks like it would be infinitely faster than booting Linux on a Pi
-Simpler - no Linux OS to deal with
-Wide voltage tolerance
I'm thinking if boot-up times are as fast as the Learning guide implies, I could wire it (fused!) into the ignition-powered circuit so it comes on with the key. This would hopefully give me the ability to show data generated while starting the engine - I've had a lot of trouble recently with starting the car. Logging the data, either on the device or via Bluetooth to a smartphone, also appeals for future versions.
Is there anything I've overlooked? Should I go out tomorrow and buy a board to hack around with? If so, do you guys recommend any particular board, or are they essentially all the same in different packages?
Thanks!
PS. I am also aware the modern arduino is probably as powerful, if not more so, than the car's own engine computer!