Vehicle manufactures are significantly increasing the production of Direct Injection Gasoline (DIG) engines to help meet the requirements of governmental regulations and the demands of consumers. While DIG powertrains offer multiple advantages over conventional gasoline engines they can be susceptible to fuel related deposit formation, specifically within the fuel injector nozzle. Fuel injector deposits have been linked to a number of negative effects that can impact the normal operation of the engine.
A DIG deposit test has been developed to evaluate Deposit Control Additives (DCA) and their effect on injector deposits. Multiple metrics for evaluating fuel injector deposits were investigated to determine a suitable method for quantifying deposit formation. Interrogation of the vehicle On-Board Diagnostic (OBD) system was identified as the optimal method for quantifying deposit formation throughout the duration of the test.
Accelerated DIG deposit testing was carried out on a wide variety of late model DIG vehicles on a chassis dynamometer for the purpose of evaluating and discriminating DIG DCA products and candidates. In addition, ongoing testing with a vehicle fleet is being conducted to determine if real-world injector deposits will form while using commercial fuels with DCAs.
Testing has shown that DCAs can be developed to specifically prevent and control deposit formation within DIG injectors. Conversely, DCAs that are formulated to reduce Port Fuel Injector (PFI) deposits may not effectively control DIG injector deposits.