Internal Injector Deposits: Correlation of the Delphi Test Rig with Production Engines.

摘要

Shortly after the formation of a Deposit Panel within the CRC Diesel Performance Group, the EMA approached the Panel and requested initiation of an urgent effort to evaluate the causes of a new internal injector deposit problem. The panel identified two proposed rigs, evaluated them, and concluded that, neither, in their present state, could discriminate among deposit forming and not deposit forming fuels. Subsequently, another rig developed by Delphi was evaluated by this panel and proved to be able to discriminate among fuels. This report provides a detailed description of a follow up project to compare the Delphi rig test results to those generated by actual engines, Cummins and John Deere, to determine if this more practical shorter-duration test rig is able to predict injector sticking tendency of fuels, eliminating expensive longer-duration engine tests using very large diesel volume. Deposit levels were dependent on the test fuel level of contamination. The Delphi rig was able to identify non-sticking fuel vs. a fuel that clearly would cause injector sticking. Regardless of the test (rig or engine) unadulterated fuel resulted in less internal injector deposits than adulterated fuels tested. Correlation between the Cummins engine and the Delphi rig was excellent. Correlation between the John Deere and the Delphi rig was poor, although it was in the direction of differentiating fuels causing injector sticking vs. those that do not; a possible explanation is that Cummins and Delphi used non filtered fuel while John Deere had a fuel filter present.