Part of the current IDID study entailed the determination of the solubility of a sodium salt in different fuel matrices in order to enable any possible correlation with this aspect to IDID formation.
The engine test cycle used in the current study included extended periods of running at close to full load / maximum power, as the extreme temperatures experienced under such conditions are considered to promote the formation of IDID. A similar type of test cycle was employed by Bosch in the engine studies they published at Esslingen in 2013.
This represents a conventional IDID test cycle and was used at Laboratory 2.
This was used to determine if the IDID contaminants also had an effect on nozzle fouling by resulting in flow and power loss.
For IDID testing the soak period was extended to 8 hours to allow the fuel system to fully cool to ambient temperature and for the deposit to have sufficient opportunity to become sticky and to adhere to the injector surfaces.
* >6 - Completed more than half the test - IDID resulted in failure to start after some time
* <6 severe and rapid IDID formation resulting in failure to start after a short running time.
This rating methodology of engine test results is still somewhat subjective but the system is reasonable given the varied effects of IDID. Note that any injector post analysis does not affect the rating score, even if IDID are visible.
Laboratory 2 used a Peugeot DW10C engine, as per the CEC IDID test procedure.
In an effort to try and establish possible alternative quantitative ways of rating the degree of IDID formation, an injector test rig was used by Laboratory 1.
Both nozzle opening pressure and mechanical response time would theoretically be altered if IDID were present and had caused needle sticking.
The base fuels were selected to see if there is a significant difference in IDID formation potential of a near-zero aromatic (predominantly paraffinic) fuel such as GTL diesel, compared with a higher aromatics containing fuel.