Malfunction localization in the intake of UMZ engines

The research findings on 30 GAZ brand motor vehicles (GAZelle and Gazelle Next) with UMZ-4216 and UMZ-A274-60 EvoTech engines, respectively, are discussed. When performing technical diagnostics, it was found that 23 vehicles had malfunctions directly in the air supply system to the combustion chamber leading to a violation of the composition of the fuel-air mixture. According to the findings, the frequency of leaks in the intake tract of these vehicles was determined which is 0.76/1 and 76.6% while these malfunctions were found in more than 2 locations. Diagnostics was carried out using specialized technological equipment, and it was determined that the main areas of leak localization were as following: interfaces of pipelines made of rubber materials with fittings with a frequency of 60.80%; damage to pipelines made of rubber materials with a frequency of 65.21%; coupling of the throttle assembly and receiver with a frequency of 47.82%; coupling of fuel injectors and cylinder head with a frequency of 47.82%. Theoretical distribution of the probability of occurrence of this malfunction was performed in terms of 100 conventional units of GAZ motor vehicles with UMZ-4216 and UMZ-A274-60 EvoTech engines using Bernoulli’s theorem which showed the equality of the relative frequency determined theoretically and experimentally and the probability of leakage. When recalculating experimental data for 100 vehicles with a theoretical probability of leakage of the intake tract, provided that Bernoulli's theorem is fulfilled, there is a direct dependence of the increased number of vehicles.