A task force studying cases of liquefied-petroleum gas vehicles stalling has seen no engine stalls in the vehicles it has checked so far.

Twenty-eight vehicles have joined the testing scheme since its launch on January 11. Six LPG minibuses are set to join it soon, the Electrical & Mechanical Services Department said.

Over the past month the task force conducted site inspections at Sinopec's LPG terminal and five LPG filling stations, as well as workshops for LPG vehicles, to examine their operation and maintenance practices.

It also convened a hearing to gauge views from the trade and collect data. It will analyse information collected to identify causes of the incidents and to recommend improvements.

On the LPG samples taken after the incidents from a number of locations including terminals and filling stations, the department has received all the laboratory test results conducted on the Mainland and some of the results conducted in Germany. With a multitude of parameters for checking LPG quality, the testing took time and results of a number of LPG tests in Germany are not yet available.

When it receives the remaining test results from Germany, the department will submit all test results and analysis to the task force for a scientific investigation into the engine stalling incidents.