## 2 Materials and Methods  
### Materials  
To have proper control of the fuel injection process during the highway driving cycle, it is necessary to know the engine operating parameters (engine speed, timing of injection, and pressure of injection) of the Isuzu4 JJ1 engine. To achieve this, an online data acquisition and analysis system will be implemented using the PAD V Launch equipment and a Micsig mini TO1104 oscilloscope. These tools allow to collect data on the fuel delivered to the combustion chamber. Tables 1 and 2 show how to use the equipment characteristics, including the injector activation time and injection pressure, under different working conditions. This analysis covers all operating conditions from an idle to full engine load.  
Once the vehicle data are obtained under real operating conditions, they will be transferred to an injection diagnostic bench, in which the values of injection pressure, operating voltage, injector energization time, injection pulse width, injection frequency, and the angular speed of the high-pressure pump are modified according to the performance characteristics of the 4 JJ1 engine. Flow data will be collected for each injection. Once the flow rates and injection volume are tabulated, a gravimetric balance is used to verify the value of the mass of fuel delivered by each activation of the injector. These variables will allow the injection rate to be calculated.  
To check that the injector works under identical operating conditions to those in the real vehicle tests, the injection pressure, energizing time, injector voltage, amperage, and operating temperature will be recorded using a current clamp and oscilloscope. These tests are carried out with 4 injectors, whose geometries are the most used in the study area in the different pick-ups. Figure 1 shows the scheme of the work methodology and the definition of each number is included in Table 3.  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Brand** & **Model** & **Engine** & **Fuel** & **Cylinder** & **Cylinder Number** \\ \hline Isuzu & D-max & 4 JJ1 CRDI & Diesel & 3.0 L & 4 \\ \hline \end{tabular}
\end{table}
Table 1: Vehicle characteristics.  
\begin{table}
\begin{tabular}{c c} \hline
**Number** & **Denomination** \\ \hline
1 & Diesel injector test bench \\
2 & Electronic Control Unit \\
3 & Injection pump \\
4 & Common Rail \\
5 & Injector \\
6 & Nozzle \\
7 & Clamp meter \\
8 & Oscilloscope \\
9 & Beaker \\
10 & Gravimetric balance \\
11 & Personal Computer \\ \hline \end{tabular}
\end{table}
Table 3: Detail numbers Figure 1.  
\begin{table}
\begin{tabular}{c c c} \hline
**Equipment** & **Brand** & **Model** \\ \hline Scanner & Launch & X-431 PAD V \\ Laptop & Dell & G3 \\ Oscilloscope & Missing & tBook mini TO1104 \\ Amperometric clamp & Fluke & 362 \\ \hline \end{tabular}
\end{table}
Table 2: Equipment characteristics.  
The characteristics of the fuel greatly influence the injection behaviour. Properties such as density, viscosity, and injection system (such as pressure and temperature) influence the characteristics of the hydraulic movement of the injector (they circulate with more or less difficulty within a hydraulic circuit). In turn, these properties affect the degree of atomization and, therefore, the air-fuel mixture that will take place in the cylinder. To study the influence of fuel in this work, two fuels were used, whose physic-chemical properties are detailed in Table 4.  
Viscor 1487 AW-2 fuel is a fuel fluid that is used to calibrate injection pumps and injectors, so it was used to calculate the injection rate, since, with this fuel, one can know the real operation of the injector and how it behaves with different nozzles according to the manufacturer's characteristics. On the other hand, diesel was used, because it is the typical fuel used in compression ignition engines.