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Some Can bus OBD2 ports will supply 20-100+ samples per second. Some cars are lucky enough that there are open source tuning solutions to monitor and/or reflash the factory image/program. Aftermarket engine management systems such as the megasquirt build a VE table automatically from the wideband sensor and other constants such as the fuel injector size and pressure, as well as variables such as the current calculated injector on time ( duty cycle). Over time just driving the car the VE table is 'auto tuned' from a target A/F ratio.
Another aspect that could help is measuring the power output of the engine without a dyno. There are mobile phone apps as well as windows apps that will do a pretty accurate chart of your power output. The fudge factors are the aero and rolling resistance corrections. Tbhe way these work are for the mobile phone, it just records the sound of the motor, and uses the frequency of the sample + a clock to figure out the rate the engine is changing. The windows one works similar, except you can use the line in port on the side of the laptop with a simple 5 component circuit to protect your laptop from voltage spikes / transients and take a direct ignition signal in as if it was an audio signal. The the computer, audio is just a data stream to deal with. StreetDyno is the program name that comes to mind off the top of my head. Avoid the apps that use an acceleraometer as the input as they are not that accurate. the output of the StreetDyno was within 5% of the numbers generated at the same time on a dynojet.
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