Deposits in common rail injectors

Deposits in injectors of combustion engines very often lead to problems during engine operation. The composition and the development of these deposits are still largely unknown. In this context, the aim of the FVV project was to identify the sources, influencing factors, formation mechanisms as well as design and fuel-related measures for preventing desposit formation. Practical investigations in the laboratory and in the test bed as well as modelling work for depicting the reactions formed the basis of the research work. Common rail injectors for engine operation with diesel and biodiesel fuels were the focus of investigation. Injector leakage temperatures as well as the aromatic compounds, oxygen content and additive content in fuel have the largest influence on deposit formation. This allows concrete recommendations to be derived for fuel management design as well as the design of injectors and engine operation.

» Through systematic and persistant research work, we have reached in the FVV a deepened understanding of the deposit formation mechanisms in injectors. We thus make a significant contribution to the design of combustion engines, especially with regard to an efficient and eco-friendly operation. «
Dr.-Ing. Manuel Boog (MTU Friedrichshafen GmbH)


Deposits in the injectors of combustion engines can lead to breakdowns. These residues are comprised of organic polymers, for which no definitive data is available regarding chemical structure or formation mechanisms. The aim of the project therefore was to complete a thorough analysis of deposits – especially in common rail injectors – as well as to describe their formation and relevant influencing factors. Moreover, the aim was to derive suitable prevention measures based on the new findings.


The research work included investigations both in the laboratory and on the test rig as well as modelling. The focus of the laboratoy tests was on the analysis of the fuels and their additives. The deposits were measured at different temperatures on a newly developed test rig outfitted with real injectors. At the same time, influencing parameters for deposit formation could be calculated using modelling methods of the oxidation process in fuels. The fuels used were fossil diesel and biodiesel (Fatty Acid Methyl Ester - FAME).


The key determinants on deposit formation are injector leakage temperatures, aromatic compounds, oxygen content in fuel as well as the content of certain additives. Measures that reduce the formation of deposits are: Avoiding fuel temperatures above 130°C; optimising the composition of the diesel fuel – paraffinic fuels are preferable to aromatic basic fuels; limiting FAME concentration; reducing the oxygen concentration in fuel; avoiding addivites based on lower-molecule polymer hydrocarbon chains. An extensive catalogue of concrete recommendations on fuel management, injector design and engine operation completes the research results.


Fuel Alteration I | Alteration of fuel properties under extreme conditions - Deposits in Common Rail Injectors | Project No. 1063 | FVV Funds

Fuel Alteration I | Alteration of fuel properties under extreme conditions - Deposits in Common Rail Injectors | Project No. 1095 | FNR/FVV Funds

Fuel Alteration III | Internal deposits of Common Rail Injectors - Prevention strategies with respect to fuel composition and injection system design | Project No 1186 | FNR/BMEL/FVV Funds



Public & FVV Funding

887.958,00 EUR

Time Period
2011-04-01 to 2011-12-31 Part I
2012-01-01 to 2014-09-30 Part II
2015-01-01 to 2017-02-28 Part III

Research Association for Combustion Engines (FVV) eV

Lyoner Strasse 18
60528 Frankfurt am Main

Specialist Agency Renewable Raw Materials (FNR) eV

Hofplatz 1
18276 Gülzow-Prüzen

Federal Ministry of Food and Agriculture (BMEL)

Wilhelmstrasse 54
10117 Berlin


Dr.-Ing. Manuel Boog
MTU Friedrichshafen GmbH

RTD Performer

Chair of Piston Machines and Internal Combustion Engines (LVK) | Faculty of Mechanical Engineering and Marine Technology | University of Rostock

Head of research:
Prof. Dr.-Ing. Horst Harndorf | I-III
Prof. Dr.-Ing. Bert Buchholz | III

Research associates:
Dr. rer. nat. Svetlana Crusius | II
Dr.-Ing. Christian Fink | II+III
Dipl.-Ing. René Junk | II+III
Dipl.-Chem. Kornelia Lau | II
Matthias Nowotny, MSc | III
Dr.-Ing. Beate Richter | II
Dr. rer. nat. Ulrike Schümann | I-III

University of Rostock

Chair of Piston Machines and Internal Combustion Engines (LVK)/Faculty of Mechanical Engineering and Marine Technology

Albert-Einstein-Strasse 2
18059 Rostock

Project Management

Ralf Thee

+49 (0) 69 6603 1349
+49 (0) 69 6603 2349


Lyoner Strasse 18
60528 Frankfurt am Main
T +49 69 6603 1345