Injector cleanliness is well characterised in the literature [1,2,3,4] as a key factor for maintained engine performance in
modern diesel cars. Injector deposits have been shown to reduce injector flow
capacity resulting in power loss under full load; however, deposit effects on
fuel economy are less well characterised.
A study was conducted with the aim of developing an understanding of the impact
of diesel injector nozzle deposits on fuel economy. A series of tests were run
using a previously published chassis dynamometer test method. The test method
was designed to evaluate injector deposit effects on performance under driving
conditions more representative of real world driving than the high intensity
test cycle of the industry standard, CEC DW10B engine test, [1]. The efficacy of different additive
levels in maintaining injector cleanliness and therefore power and fuel economy
was compared in a light duty Euro 5 certified vehicle.
Full load power loss in low or non-additised fuels was observed (~3%), whereas a
keep-clean dose of a deposit control additive (DCA) fully maintained
performance. Furthermore, a statistically robust link between injector fouling
and an increase in specific fuel consumption (~0.7%) at steady state was
established.
In addition, mechanisms were proposed for the link between injector fouling and
changes in fuel consumption derived from in-cylinder measurements throughout the
test duration, as well as exploration of how fuel consumption effects change
across the operating range outside of the test cycle.