New Lubrizol test data demonstrates the effectiveness of 9040 Zer0 in tackling one of today’s toughest fuel challenges – cleaning internal diesel injector deposits. While previous XUD9 and DW10 testing confirm the ability of Lubrizol® 9040 Zer0™ Series to clean nozzle coking deposits on diesel fuel injectors and protect against power loss, including in the latest common rail diesel fuel systems, the new engine test data now illustrates how the product, at reasonable treat rates, also performs deep inside the injector to effectively clean up performance-robbing deposits.
Unlike conventional coking deposits which form on the tips of fuel injectors and within the fuel spray holes, internal diesel injector deposits (often abbreviated to “IDID”) are found within the injector body itself, such as at the armature group, on the piston and nozzle needle and inside the nozzle body. These deposits can slow the response of the fuel injector, or cause sticking of moving internal parts, which may result in loss of control of injection event timing, as well as of the quantity of fuel delivered per injection. Hence, a build-up of these deposits can lead to a loss of vehicle drivability and rough engine running, as well as unwanted variations in power and loss of fuel economy. While European OEMs are principally concerned that IDID formation could hinder future injector developments, many North American heavy duty engine manufacturers have already expressed an urgent concern regarding this issue, with some experiencing recurring field problems.
There appear to be at least two different types of internal injector deposits reported. The first comprises of `waxy’ or `soap’ deposits, while the second type appears to be carbonaceous, or of a lacquered appearance. Many of the problems reported in field use in the United States appear to be of the waxy form, while problems highlighted in European engines focus on the lacquer type deposits.
Examination of older technology fuel injectors used in heavy duty engine testing indicates that internal diesel injector deposits have probably been in existence for some time, as indicated by the image of a cut-away unit injector from the Mack E-Tech V-Mac III 12 litre engine shown in Figure 1. (The engine is compliant with 2004 US emissions regulations.)
However, internal injector deposit build up appears to have been less critical in older designs, probably as a result of greater tolerances between moving parts. A number of theories have been proposed in explanation of the increasing significance of IDID incidences.
Major heavy duty engine manufacturers, have turned to Lubrizol for help with internal injector deposit problems. Through our efforts to better understand IDID causes, its effects and solutions, Lubrizol has conducted in-depth research and testing with these OEMs to tackle the issue. Although speculation concerning the causes of IDID may continue for some time, with the help of advanced Lubrizol 9040 Zer0 Series additive technology, we have been able to successfully remove and prevent the internal injector deposits experienced by global OEMs in their latest most complex engines, both on test stands and in the field.
Combinations of fuel additives such as mono-acidic lubricity improvers and conventional succinimide deposit control additives (DCAs) have been suggested as one of the possible causes of IDID. These types of additives have many years of successful field use and are widely known to be extremely beneficial in preventing wear and deposit formation in fuel injection systems. Lubrizol has recently tested our successful conventional succinimide DCA in combination with a proven mono-acidic lubricity improver in the common rail DW10 engine looking specifically for internal deposits, using an extended version of the CEC F-98-08 method. No evidence was found that these additives contribute to IDID deposits. During this series of DW10 tests, no unusual operating parameters were observed. After the test, disassembly of the fuel injectors showed completely clean internal parts with no evidence of deposits.
A second engine test has also been specifically developed for evaluation of IDID formation factors, using an engine that had suffered from waxy `soap’ deposits in actual field usage in a number of North American geographic locations. The engine is a 6.8 litre common rail model compliant with U.S. Tier 3 off-road emissions standards. An analysis of failing injectors taken from this engine indicated the presence of sodium salts of the fuel corrosion inhibitor dodecenyl succinic acid (DDSA). Operating the test engine in the presence of fuel contaminated with sodium salts of dodecenyl succinic acid resulted in significant power loss corresponding with decreases in engine exhaust temperatures. Disassembly of the injectors from the test confirmed internal deposits, the composition of which was consistent with the presence of sodium DDSA salts.
In subsequent testing, the Lubrizol 9040 Zer0 Series deposit control additive was shown to prevent the formation of these internal deposits and was also shown to remove them when already present in fuel injectors. Testing was also carried out using fuel containing sodium and mono-carboxylic lubricity improver. In contrast to the testing carried out with DDSA, the mono-carboxylic acid treated fuel showed no impact on engine operation and no IDID was observed on disassembly of the fuel injectors, thereby indicating that proposed IDID mechanisms involving this class of lubricity improver are incorrect.
Lubrizol 9040 Zer0 Series offers total deposit control capability. In addition to providing outstanding control of conventional nozzle coking deposits, both in mineral and biodiesel blended fuels, it is also highly effective in the prevention and removal of internal injector deposits. Lubrizol’s market proven deposit control additive offers a true one stop solution for both internal and external nozzle coking issues in both old and latest technology diesel engines.