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Date of Award


Document Type

Master's report

Degree Name

Master of Science in Mechanical Engineering (MS)

College, School or Department Name

Department of Mechanical Engineering-Engineering Mechanics

First Advisor

Jeffrey D. Nabor


Jeremy Worm


This report details an investigation of the effect of solid deposit formations (SDFs), in the induction systems of Spark Ignited (SI) Port Fuel Injected (PFI) engines, on engine performance and control. The combustion of petroleum based fuels and the presence of lubricating oils in an internal combustion engine creates SDFs in the engines induction system. This report investigates the effect these SDF's have on the performance and control of the engine. Many chemical cleaning products exist on the market today to remove or reduce induction system deposits. It is often advertised with these products that the removal of SDF's will result in improved engine performance. Negative effects on engine performance and control could cause the engine to perform at lower efficiency and produce additional undesirable emissions. It is necessary to understand the effects on engine performance and control, the ramifications, and how to properly address SDF's in the induction system.

Multiple vehicles were evaluated to investigate changes in engine operating characteristics in three different SDF states. In these different states, the quality and quantity of these SDF's on fuel and induction system components were observed and recorded. Three different states were chosen to be "dirty", "chemically cleaned", and "mechanically cleaned". The vehicles were tested on a chassis dynamometer to monitor both engine operation characteristics in steady-state and transient conditions. The steady-state evaluation investigated general engine performance metrics including Brake Specific Fuel Consumption (BSFC), volumetric efficiency, and torque output in correlation to SDF levels. The transient evaluation investigated control stabilization in a tip-in tip-out maneuver at three SDF states.