The structure of the automobile service, since the beginning of the independence of Ukraine, has changed acutely. The number of private vehicles, the quality of service of which depends on the owner only, has increased. In addition to already existing automobile transport enterprises which has at least some existing production facilities with available cars of post-Soviet production and Russian cars of the middle time of Ukraine's independence, a large number of private small motor vehicles companies without any production base have appeared (in the best occasion with the available storage area), technical condition of the movable composition of which does not meet the requirements of European countries and the main transporting direction of these enterprises was concentrated in the directions of post-Soviet countries.
In order to maximize efficiency, the owners of such vehicles carry out the transformation of power supplies to the system supplied with gas fuel. Despite the sufficient number of advantages, such refurbishment requires the introduction of constructive modifications and adjustments also in the ignition system of motor vehicles. And here, in the absence of systematic state control, many of the car owners in pursuit of maximum economy, trying not to make changes, causing violations in the work of car systems, which leads not only to the growth of fuel consumption and reducing of the effective performance of the engine, but also to increasing of emission of toxic components with the exhaust gas flow of the car engines. In conditions of Ukrainian cities, where emissions of toxic components by transport sources are up to 90% of all harmful effects , the search for ways to improve the system of technical service of vehicles is relevant in order to control and reduce the level of environmental hazards from the operation of vehicles. Therefore, researches that focus on determining the influence of regulation of the ignition system of engines powered by gas fuel, on the example of the spark plug gap influence on the indicators of the content of the components of the exhaust gases, are relevant.
The method of research on the influence of the spark plug gap on the change in the composition of exhaust gases was developed in the paper, the research was carried out on ZAZ Lanos 1.4 engine MeMZ 317, on which is an assembly of gas equipment of the 4th generation Stag 200 GoFast. All experiments were carried out on the equipment of the Training Center for Computer Diagnostics of Vehicles "Lviv Polytechnic – Bosch Academy". A set of new Champion RN9YC spark plugs was used, the gap of which was changed from 0.6 to 1.4 mm with a pitch of 0.1 mm.
According to the values of the gap between the electrodes of the spark plug, with the use of Bosch BEA 460 gas analyzer, the content of the following components of the exhaust gases CO, HC, O2 and CO2 is determined for two engine's crankshaft frequencies.
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