Abstract: A device and corresponding method for enabling a user to accurately control, monitor, and evaluate performance of a vehicle. A portable programmable computer device that a user can readily plug into a diagnostic connector port of the vehicle for providing the controlling, monitoring, and evaluating functions. Accurate detection of the start time of first movement of the vehicle is made based on data from an accelerometer, independent of the onboard diagnostic system and its diagnostics port. A clock is started for measuring time such that the precise time taken to reach the time-stamped first velocity value from the engine computer via the diagnostic port is determined. Data from the accelerometer and diagnostic port is analyzed and selectively used for accurately and reliably correcting for errors in velocity data from the onboard diagnostic system including latency error and errors due to the vehicle exhibiting wheel spin.

Abstract: A system, device, and corresponding method for enabling a user to accurately control, monitor, and evaluate performance of a vehicle. A portable programmable computer device that a user can readily install by plugging it into a diagnostic connector port of the vehicle. The system includes a detector for detecting the start time of first movement of the vehicle independent of the on board diagnostic system. Velocity data from the onboard diagnostic system is time stamped by a clock in the device and stored. Velocity curves are generated from the velocity data and time stamps. Wheel spin is accounted for by smoothing the velocity curve to determine a point of inflection in the velocity indicative of termination of wheel spin and creating correcting velocity and acceleration curves by solving equations from the inflection point backwards on the curve down to time zero. From the corrected curves, an accurate distance is calculated.

Abstract: A device and corresponding method for enabling a user to accurately control, monitor, and evaluate performance of a vehicle. The system includes a portable programmable computer device that a user can readily install by plugging it into a diagnostic connector port of the vehicle for providing the controlling, monitoring, and evaluating functions. The present invention enables a user to perform performance tuning of the engine, provides dynamometer type functions such as horsepower and torque measurements, and provides a virtual drag strip function for accurately measuring acceleration data. According to an alternative embodiment, a monitor mode is provided for enabling the user to monitor selected characteristics of the vehicle and a diagnostics mode is provided for providing for the identification and display of diagnostic trouble codes (DTCs) with informative text descriptions. The present invention also enables the clearing of selected DTCs without requiring expensive customized equipment for that purpose.