The Potential of Using the Ion-Current Signal for Optimizing Engine Stability - Comparisons of Lean and EGR (Stoichiometric) Operation

Research output: Chapter in Book/Report/Conference proceedingPaper in conference proceeding


Ion current measurements can give information useful for controlling the combustion stability in a multi-cylinder engine. Operation near the dilution limit (air or EGR) can be achieved and it can be optimized individually for the cylinders, resulting in a system with better engine stability for highly diluted mixtures. This method will also compensate for engine wear, e.g., changes in volumetric efficiency and fuel injector characteristics. Especially in a port-injected engine, changes in fuel injector characteristics can lead to increased emissions and deteriorated engine performance when operating with a closed-loop lambda control system. One problem using the ion-current signal to control engine stability near the lean limit is the weak signal resulting in low signal-to-noise ratio. Measurements presented in this paper were made on a turbocharged 9.6-liter, six-cylinder natural gas engine with port injection. Each cylinder was individually controlled by a cylinder control module (CCM). A high turbulence combustion chamber was used to be able to operate with highly diluted mixtures. Comparisons between lean and EGR (stoichiometric) operation were made to investigate the potential of using the ion-current signal to control engine stability (cylinder-to-cylinder and cycle-to-cycle variations). A much stronger ion-current signal was found with EGR compared to lean operation, for the same load and comparable emissions.


Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Energy Engineering


  • Spark Ignition, Control, CNG, Natural Gas, Ion Current
Original languageEnglish
Title of host publicationSAE Special Publications
PublisherSociety of Automotive Engineers
Number of pages13
Publication statusPublished - 2003
Publication categoryResearch
EventSAE 2003 World Congress and Exhibition - Detroit, Michigan, United States
Duration: 2003 Mar 32003 Mar 6

Publication series

ISSN (Print)0099-5908


ConferenceSAE 2003 World Congress and Exhibition
CountryUnited States
CityDetroit, Michigan

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