Research of the effect of washing of fuel system engines on traction-speed properties of cars

The results of tests on the Cartec LPS 2510 dynamometer stand (test mode P-max) according to ISO 1585 are presented. Regardless of car model, year of manufacture, mileage and engine size, power unit power loss and a decrease in torque are observed. Flushing the fuel system with special fluids and ultrasonic cleaning of the nozzles allow the restoration of engine power and torque.


Introduction
Traction-speed properties of a car are one of the main indicators of its effectiveness. Their evaluation is carried out by calculating the parameters of power and traction force or by determining the tractionspeed parameters (TSP) on roller stands [1][2][3][4][5][6]. Using the stands, they estimate not only the fuel mixes, but also determine the irregularity of the fuel dosage, estimate the energy and environmental parameters of engines operating on various fuels, including ethanol added to gasoline [7][8][9][10][11][12].
On the power (dynamometer) bench, the power at the wheel and the power of the mechanical losses (power loss to work in the vehicle's transmission) are measured. The engine power on the traction stands is not directly measured, but is calculated as the sum of the power at the wheel and the power of mechanical losses. The change in engine power depends not only on the amount of car mileage, but also on many factors, which include pollution of the injectors, the presence of deposits and carbon deposits on the parts of the power unit. Timely assessment of power, adjustment, troubleshooting of engine components will improve the efficiency of the vehicle.

Experimental part
The test was carried out with cars having different mileage. So, for example, by the time of his research, the Chevrolet Lanos SX (release of 2009) had a mileage of (L) of 100 and 170 thousand km, and a  (Table 1). The power (N) and torque (M) of the engine were determined on a Cartec LPS 2510 dynamometer (test mode P-max) according to ISO 1585 ( Figure 1). The standard regulates the measurement of net powerthe real engine power. For a correct assessment of the N and M parameters recorded at the stand (after removing the initial characteristics of the engine), the injection system (IC) of the vehicles was washed with WYNN`S liquid. The engine was flushed with WYNN`S fluid by supplying it from a single-circuit reservoir (GX-100B) running on compressed air.  Table 1 shows the passport data of gasoline engines of cars and the current maximum value obtained at the stand. It is well known that the loss of power of the power unit associated with the natural wear of engine parts is ~ 10% of the passport parameter (nominal) NH. Indeed, from data analysis ( Table 1) it follows that in most cars the power of the power unit differs from Nnom by 3 ... 12%. The exception was the car Chevrolet Lanos SX: engine power with mileage was 68 ... 78% of the passport parameter Nnom.

Analysis of the results
In figures 2-4 show graphic protocols for testing cars on the Cartec LPS 2510 dynamometer bench in accordance with ISO 1585.
From the analysis of the presented curves ( Figure 2, 3), it follows that the dependencies of power on the crankshaft rotation speed are different for the Chevrolet Lanos SX and Chevrolet Lacetti. Moreover, the dependence of power on the crankshaft rotational speed of the Chevrolet Lanos SX is typical for engines with unchanged intake manifold geometry, in which gas distribution processes are influenced by the installation of camshaft timing [13].
Crankshaft rotation speed, n, min-1   Flushing the engine power system is reflected in its power positively. Its scatter is much lower than the scatter of the values of this parameter recorded before cleaning the injection system (Figure 2 and 4). The amount of power increases after washing.
The scatter of power values, most clearly manifested in the testing of the car Chevrolet Lanos SX, reaches values much higher than the scatter values that were obtained in tests with the Chevrolet Lacetti. So, at n = 4600 min -1 , the power can reach values from 41 kW to 45 kW ( Figure 2). Therefore, not three, but 5 parallel tests were conducted. The correspondence of the taken number of experiments to the required number of measurements (nх) ensuring the representativeness of the sample was evaluated by the expression [14]: (1) where ta is the Student's criterion,  2 is the variance of the general population; Δx is the measurement error.
So, for the values Δx = 2.5 kW, ta = 2.8,  2 = 3.9 kW 2 , obtained by processing the maximum engine power data (before washing the injection system), the value of nx was 5, identical to the number of tests performed.
Error estimation was performed using the expression [6]: where τmax is the maximum relative deviation; xav is the arithmetic mean value of the parameter; xchchecked parameter value; sn is the standard deviation.
According to expression (2), the values of τmax for the minimum (xav) and maximum (xch) power values were calculated by comparing the τmax with the table value.
Data processing was performed using statistical functions and analysis of Microsoft Office Excel package.

Discussion
The presented data ( Table 2) indicate that the maximum engine power with a mileage of 100 thousand km is less than Nном, by 14.3 kW, and with an operating time of 170 thousand km. at 20.0 kW. Flushing the injection system will increase power by 4-6 kW. Unlike the Chevrolet Lanos SX engine, the power of the Chevrolet Lacetti power unit increased by 2 kW (Table 3).
The contamination of nozzles with deposits, varnishes and impurities leads to the need for ultrasonic cleaning [15,16]. Therefore, the nozzles were cleaned with ultrasound, using an ultrasonic bath, which is part of the device for cleaning and analyzing AT & E fuel nozzles (model HP-6B) [17]. Evaluation of the degree of cleaning of the nozzles by ultrasound was evaluated by their performance on the AT & E installation. A solution consisting of water, ethanol, and surfactants was used as a cleaning agent.
The evaluation of the working status of the injectors was carried out in automatic and manual modes for setting the frequency (nτ), width (τ) and the number of pulses (Nτ). The parameters of the automatic mode are presented in Table. 1 (performance in cm 3 ). In the manual mode: 1nτ = 2400 min -1 , τ = 12 ms, Nτ = 2000 pulses; 2nτ = 3600 min -1 , τ = 6 ms, Nτ = 2000 pulses. The first setting simulates a multipoint spray and the working condition of the injectors at maximum load, the second onea multipoint spray and working condition at high speeds of the vehicle. The time spent on testing in all experiments ranged from 30 to 43 sec. In table 2 shows the change in performance (Δ), expressed in cm 3 ·min -1 .
From a comparison of the data ( Table 4) it follows that the performance of the nozzles changes after exposure to ultrasound. Therefore, in order to establish the reliability of the data obtained, tests of SIEMENS DEKA ZMZ 6354 (SIEMENS) and BOSCH 280 150 996 (BOSCH) injectors were conducted with a mileage approximately equal to the mileage of the Chevrolet Lanos SX.
SIEMENS nozzles, unlike BOSCH and GM, were prewashed before ultrasonic cleaning by placing in a beaker filled with a solution (the volume of the liquid phase was 20 ml) under a slope so that only the lower part of the device was washed with a magnetic stirrer. The cleaning process was carried out with the help of a "reanimator"nozzle-Reanimator V2.0 on the objects of study working impulses. Firstly it was carried out for 30 seconds, and then for 1 minute. After each such impact, the nozzles were left (without turning off the mixing) for 10 minutes in a beaker and then measured pH (pH) and electrical conductivity (σ) of the liquid phase. Before measurements, the liquid entering the upper part of the nozzle was taken with a single-channel pipette and placed back into the beaker. The total time of contact of the liquid with the object of study and the temperature of the liquid phase were, respectively, 1 hour and 200 ° C.   Table 5 shows the performance changes of the SIEMENS and BOSCH nozzles. From a comparison of the data (Table 5), it follows that the performance of BOSCH nozzles increases or does not change after exposure to ultrasound. Consequently, the data obtained for GM, indicating a decrease in productivity after exposure to ultrasound, is the measurement error. Test results in which performance does not change should be considered reliable. That is, not all contamination can be removed by exposure to ultrasound. After pretreatment (using the "reanimator"), productivity increases (Table 5, SIEMENS). Data with zero Δ is not observed. The relative error in measuring performance was ± 0.4-1.0%. When calculating the errors in determining the performance, the value of the confidence probability was α = 0.95, and the value of the confidence limit (tα) was 2.262.

Conclusion
The use of ultrasound as a cleaning method has been known for a long time. Therefore the result obtained in the study is quite natural. However, taking into account the fact that the SIEMENS nozzles were subjected to preliminary washing (using a "reanimator"), it should be concluded that it is advisable to monitor the operating parameters after applying this procedure.
From a comparison of the data (Table 6), it follows that ultrasonic cleaning, after flushing the fuel system with WYNN`S liquid, allows the engine to recover another 2 kW.  Thus, from the test results and their analysis presented, it follows that regardless of the vehicle model, year of production, mileage and engine size, the power loss of the power unit and the decrease in torque value are recorded. Flushing the fuel system with WYNN`S fluid and ultrasonic cleaning of the nozzles will allow you to restore engine power and torque. It has been established that pretreatment of the nozzles with a washing solution using a "resuscitator" (Reanimator V2.0) will increase the effectiveness of the effect of ultrasound on decontamination.

Acknowledgments
The publication has been prepared with the support of "Peoples' Friendship University of Russia University program 5-100".