Driven by increasingly stringent tailpipe CO2 and fuel economy
regulations, gasoline direct injection (GDI) engines are enjoying rapidly
increasing market penetration. Already more than 50% of newly produced vehicles
in the US and western Europe employ direct-injection technology and many markets
in Asia are also seeing an increasingly rapid uptake.
However, with the adoption of GDI engine technology, which is able to push the
boundaries of engine efficiency, new challenges are starting to arise such as
injector nozzle deposits, which can adversely affect performance. Multi-hole
solenoid actuated fuel injectors are particularly vulnerable to deposits formed
when operated on some market fuels. In order to address this challenge, the
development of a reliable industry test platform for injector cleanliness in GDI
engines is currently underway in both the US and Europe.
This study shows the successful application of a mass produced GDI bench engine
test platform (VW 1.4 L TSI 90 kW; engine code CAXA; engine family EA111) to
differentiate different fuel formulations, at a 99% statistical confidence
level, based on an engine metric correlated to injector cleanliness. In this
study, a European (EN228 compliant) market representative test fuel was used
throughout the entire investigation -i.e. no pro-fouling dirty-up fuel
components were required to accelerated deposit formation within a reasonable
test duration. The study makes two cross-comparisons between three different
fuel formulations and the bench engine deployed is shown to be a highly
sensitive test platform to differentiate fuels with different levels of deposit
control additive (DCA). Fuels formulated with appropriate DCAs help restore
fouled injectors to their original performance level.
