Tool Briefing p This screenshot from a lab scope shows the cranking vacuum using a transducer before (left) and after (right) the intake was cleaned. gases and oil residue are not “washed” from the back of intake valves. Heat from EGR systems, or heat generated from exhaust valve timing, may bake the residue into hard carbon deposits. The carbon deposits then create turbulence in the air flow entering the engine through the intake valve and can cause an uneven mix of the air and fuel. If the carbon deposits are significant, a vacuum gauge will show both a lowerthan expected reading and may show slight pulsations of the needle. A more precise tool to perform this test is a lab scope and a pressure transducer. Since you are able to set the time of the waveform, you can see the vacuum pulsations more easily with the lab scope. Connect the transducer to a manifold vacuum source and to your lab scope. Disable the fuel pump and/or the ignition and crank the engine. The waveform will show uneven amounts of vacuum as well as some “hash lines” indicating turbulence in the intake system. 5 DETERMINE THE EXTENT OF CARBON One of the best ways to determine how severe the carbon issues are, and therefore the best way to repair the issue, is to use a borescope. Using the borescope to look inside the cylinders through the spark plug hole may not show much carbon. Typically, most carbonization issues occur in the intake valve, while the tops of the pistons remain fairly clean. Accessing the back of the intake valve to observe how much carbon is built up on the valve stem and back of the valve usually involves removing the intake plenum, then inserting your borescope into the intake valve area. If significant carbon is detected, there are a few different options available to remove it. 6 REMOVE THE CARBON 74 PTEN OCTOBER 2016 www.VehicleServicePros.com The best way to remove carbon is to follow the vehicle manufacturers’ recommended procedure, which can usually be found by looking at TSBs or service campaigns in your vehicle information source. There are both induction and fuel injection cleaners available to the aftermarket. Cleaners can be a chemical additive or a chemical that is introduced to either the fuel system or intake system. Fuel system cleaners are commonly known as fuel p Accessing the back of the intake valve to observe how much carbon is built up on the valve stem and back of the valve usually involves removing the intake plenum then inserting a borescope, like the ATS IC Inspection Camera, into the intake valve area. p Examples of major (top image) and minor (bottom image) intake valve carbon buildup, taken with a borescope. Images provided by: Automotive Test Solutions Images provided by: Automotive Test Solutions injection cleaners and work well to clean fuel injectors as well as intake ports and valves on PFI systems engines. However, even though fuel system cleaners will work to clean fuel injectors on GDI systems, they will not help clean carbon deposits in areas where fuel does not reach. Intake system cleaners, more widely referred to as induction cleaners, are introduced into the intake manifold or throttle body where they can be distributed throughout the air induction system and reach areas where a fuel additive could not get to on a GDI engine, such as the back of the intake valves. Some of the established de-carbon methods include using approved solvents and delivering them through the intake system using an apparatus to dispense these fluids, such as the OTC 7448 or 7448A Fuel Injection Cleaner Canisters. We have had years of success using BG Products, such as the BG Fuel Injection Circle 216 on card, or enter at “e-inquiry” on VehicleServicePros.com
Professional_Tool_And_Equipment_News_October_2016
To see the actual publication please follow the link above