Influence of Fuel System, Fuels Types and Spark Plug Types on CO Gas Exhaust of Motorized Vehicles

Fuel system, type of fuel and type of spark plug, are the determining variables in producing exhaust gas in motorized vehicles. Pollutants produced by motor vehicle emissions include Carbon Monoxide (CO), carbon dioxide (CO2), Sulfur Dioxide (SO2), Nitrogen Monoxide (NOX), Hydrocarbons (HC), Lead Particles (PB), smoke and ash. These pollutants can cause interference in humans, animals, plants and other objects. The study was conducted to determine the effect of the main variables of the fuel system variables (Carburetor and EFI), type of fuel (Premium octane 88 and Pertamax octane 92) and the type of spark plugs (standard spark plugs and spark plugs Iridium) on CO gas exhaust. The test tool used to determine the value of the percentage of vehicle exhaust is a Gas Analyzer and the test vehicle used is a 4-step motorcycle. The research method uses factorial design and variable analysis using Yates's algorithm. The test results show that the effect of the fuel system is -1,272 (Carburetor), the effect of fuel type is -0,268 (Premium), and the type of spark plug is -0,018 (standard spark plug), so the most influential variable on CO gas output is the fuel system using the Carburetor.


Introduction
The fuel system, the type of fuel and the type of spark plugs, are important of a motorized vehicle. Changes to the fuel system from the Carburetor to Electronic Fuel Injection (EFI) are technological changes in setting the amount of fuel and air entering the combustion chamber. Comparison of the volume of fuel and the air entering the combustion chamber, greatly determines the output of combustion (exhaust gas).
The development of premium fuels (octane 88) and pertamax (octane 92), as well as the types of spark plugs Standard and Iridium, are technological developments, one of which is to improve vehicle efficiency and be environmentally friendly.
Tests are carried out to determine the greatest effect on exhaust gas Carbon monoxide (CO), from the vehicle fuel system, the type of fuel used and the type of spark plug used.
Gas CO is a gas that is very dangerous for health. If a person breathes CO gas in low levels, that person can experience shortness of breath and pale. But if in a high levels can cause fainting, even death. Gas that is colorless, odorless, tasteless and non-stimulating, therefore carbon monoxide gas is difficult to detect.
Community knowledge of variables that produce CO gas is very necessary. This is to anticipate the possibility of an accident due to exhaust gas CO. With this knowledge, it is expected that people can choose the type of vehicle and the type of fuel that will be used

Fuel System
On the Otto engine there is a fuel system consisting of a fuel supply system and a fuel gauge system. The fuel supply system functions to deliver fuel from the fuel tank to the fuel gauge system. Whereas the Fuel Gauge system on the Otto engine that uses a carburetor or fuel injection system functions as follows:  Measure the amount of air and fuel to obtain a mixture of air fuel that can be burned quickly and perfectly in the cylinder.  Atomizing and spreading fuel in the air flow or known as Air Fuel Ratio (AFR).
The parameter is called Air Fuel Ratio (AFR), which is the ratio of the amount of air to fuel in weight. The theoretical comparison value for the perfect combustion process or also called stoichiometric AFR for the Otto motor is around 14.7. The fuel system must be able to produce an air ratio of the fuel needed to be cylinder in accordance with the engine operating conditions. For example at cold start times, a mixture that is rich in fuel is needed. In the condition that the engine is still cold automatically, the fuel that evaporates is only partially so that additional fuel is needed to obtain the mixture which is ready to be burned in the cylinder. The construction of the carburetor is simple and has been used in almost all of the engine Otto in the past. But lately, in order to fulfill the demand to clean exhaust gas (exhaust emission), the use of fuel that is more economic, improved driving capability and so on, the current carburetor must be equipped with additional equipment to make the carburetor system complicated.
To replace the carburetor system, then the EFI (Electronic Fuel Injection) fuel system is used, which is injecting fuel done electronically equipped with sensors to detect engine working conditions and ECU (electronic control unit) to determine the duration of fuel injection and set ignition time.
The differences between the carburetor and efi systems are as follows a) How it works to mix fuel with air.
In the carburetor system, mixing fuel and air is caused by the vacuum of the combustion chamber which occurs due to the step of suction piston. If on the EFI injection system, mixing fuel and air is done by the injector on the orders of the ECU which considers signals from sensors that spread throughout the engine and exhaust. When the engine temperature is cold the engine requires a rich mixture of gasoline to start the engine. In the carburetor system, to enrich the gasoline mixture, choke is activated so that the fuel ratio becomes rich. For the fuel injection system, the temperature sensor will report the cold engine temperature so that the ECU instructs the injector to enrich the gasoline mixture.
c) At the time of acceleration. At the time of motor acceleration requires a mixture of fuel that is quite rich around 8: 1 AFR. The carburetor system is assisted by an accelerator nozzle which functions to increase the supply of fuel to the engine when the gas throttle is opened suddenly. If the throttle position sensor injection system will send a report to the ECM that the throttle is opened suddenly and the ECM will instruct the injector to enrich the gasoline mixture. d) At high rpm. At high rpm, the main jet carburetor and jet pilot systems are fully open to produce a large amount of power. If the fuel injection system, the throttle position sensor and vacuum sensor in the intake manifold both send a signal to the ECM to slightly enrich the mixture.

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Influence of Fuel System, Fuels Types and Spark Plug Types on CO Gas Exhaust of Motorized Vehicles

Emissions
Exhaust gas emissions are pollutants that pollute the air produced by vehicle exhaust gas (Wardan Suyanto, 1989: 345). The vehicle exhaust gas intended here is the remaining gas from the combustion process which is discharged into the air through the vehicle's exhaust line. The four emissions are Hydrocarbon (HC) compounds, Carbon Monoxide (CO), Nitrogen Oxide (NOx), and particles that emit from the exhaust gas. a) Hydrocarbon Compounds (HC).
It occurs because the fuel has not been burned but has been wasted with the exhaust gas due to incomplete combustion and evaporation of fuel. Hydrocarbon compounds (HC) are divided into two namely unburned fuels so that it comes out into raw gas, and the fuel is broken down because the heat reaction turns into another HC group that comes out with the exhaust gas. C8H18 → H + C + HC (1) b) Fire produced by spark plugs in the combustion chamber moves very fast but the temperature around the walls of the combustion chamber is low. This results in a mixture of fuel and air in the low temperature area that is quenching zone. The unburned fuel mixture is then pushed out by the piston to the exhaust c) At the time of deceleration, the gas valve (throttle valve / valve) closes so that the engine brake occurs even though the engine speed is still high. This will cause a large amount of fuel suction, the mixture becomes very rich and many unburned fuels are wasted. (on the carburetor fuel system) d) Overlapping steps (the inlet and exhaust valves together open) are too long so the HC functions as a rinse / cleaning gas (occurs especially at low speed, carburetor fuel systems). HC compounds will have an impact on the eyes, resulting in throat pain, lung disease and cancer. Graph of the relationship between air-fuel mixture and HC can be observed in the figure below. Figure 3. Relationship between Mixtures Air-Fuel and HC e) Carbon monoxide (CO), created from fuel that is partially burned due to incomplete combustion or due to a mixture of fuel and air that is too rich (lack of air). The carbon element in the fuel will burn in a process as follows: CO, which is released from the remaining combustion products, is largely influenced by the ratio of the mixture of fuel and air sucked by the engine. To reduce CO the comparison of this mixture must be made thin, but this method has other side effects, namely NOx will be easier to arise and the energy produced by the engine will decrease. CO is very dangerous because it is colorless and odorless, resulting in dizziness, nausea, breathing disorders, and even death. The graph of the relationship between a mixture of air-fuel, CO and CO2 can be observed in the figure below.

Methodology
The method used in the study was using factorial design and Yates' algorithm.

a. Factorial Design
Factorial design is a method that is very important to determine the influence of several variables that affect results. Conventional experiments only measure one influence of one variable to find out the results. The factorial design can combine several variables in the same factorial test, besides that it can reduce the number of unnecessary experiments. With factorial design values can be known.

Basic principles
(Example) If there are 3 variables Temperature T, Concentration C and Catalist K, will be analyzed, where each variable has 2 specific values (-and +), to determine the effect of each variable, then factorial design 2 3 .

b. Yates's algorithm
Yates's algorithm is a method for determining the main effects of each variable and the effect of a variable relationship. After the results of the factorial design test were obtained, then processed these values with Algorithm Yates's, as follows:

Testing Results and Analysis
The percentage of CO exhausts gas test results: