Measurements of time-resolved particulate matter emissions from a high-emitting light-duty diesel vehicle were made using an electronic particulate matter sensor developed at the University of Texas. The sensor, which is threaded directly through the exhaust pipe wall, detects the time-resolved mass concentration of carbonaceous PM in undiluted vehicle exhaust. The sensor works by detecting an electrical current that is created between two electrodes that have a large potential difference across them; a current is created when particles are present. The sensor was used to characterize the PM emissions from a Chevrolet Equinox SUV which had its original gasoline engine replaced with a 1.9 liter Fiat/Opel turbo-diesel. The vehicle was without a diesel particulate filter (DPF) and had transient PM emission concentrations during accelerations as high as 1000 g/m3. The sensor’s output closely followed exhaust opacity. PM emissions were found to be highest for rapid accelerations and were strongly correlated with pedal position, which can be taken as a surrogate for the fuel delivery per cycle. The sensor was calibrated against gravimetric filter measurements of dry PM mass captured from the vehicle’s exhaust in sample bags.

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