Evaluation of the Powertrain Condition Based on the Car Acceleration and Coasting Data 2018-01-1771

Diagnosis of the car is a necessary means for early detection of developing malfunctions. A technique for diagnosing on a short road based on the acceleration in the second and third gears and coasting from 50 or 40 to 20 km/h is proposed. The results should be compared with the reference values calculated, taking into consideration the speed rolling resistance dependence, described by the square trinomial, the speed air resistance dependence with the variable exponent, the losses of the transmission idling mode and the progressive total resistances decrease at speeds below 25 km/h. The general speed dependence of the total resistance is described by a sixth-degree polynomial but not the second-degree one, as many researchers believe. The experimental check was performed on a subcompact sedan with 1.6 atmo engine. Weight of 1370 kg. First class road with an average rise of 0.0182, asphalt in good condition. There was no wind.

Measuring and recording equipment: GPS receiver Magellan Triton 300, digital cameras Canon, an anemometer. The processing of video recordings was carried out in the Virtual Dub and MS Excel programs. The evaluation based on the acceleration and coasting times showed the engine technical condition better than the nominal one. According to the records of the II, III and IV gear’s torque curves were restored. The curves are far from the nominal steady-state curve, but are close to the chassis dynamometer curve. The reached torque value exceeds the maximum passport one by 5-10 Nm. So, the on-road diagnostics with simple equipment provides true information, suitable both for the vehicle condition assessing and for research.