FUELS

TESTING DIESEL INJECTORS

in this practical, i was required to test four diesel injectors.

the tasks that i completed were observing the spray patterns, checking for leakages and repairing any faulty ones.

we used a spray pattern tester which used a hydraulic fluid to simulate diesel

above is one the four diesel injectors used. to perform the test i fitted the injector onto the tester like below

the tester was already preset for this test but it is adjustable to how you want to perform the test.basically the tester applies air pressure to the injector like in a car and the spray pattern which the fluid forced out has shows if it is good for further use. of the for that i tested only one had a pattern that was off,more like a squirt and i changed the needle valve to fix the problem

below are the results i obtained during the test

Injector1	Failed the spray test. Disassembled the injector and refitted needle valve and worked 132 bar
Injector2	Passed spray test 209 bar
Injector3	Passed spray test 174 bar
Injector4	Passed spray test 165bar

EMISSIONS




40% of the planet's air pollution is attributable to the burning of fossil fuels (Petroleum). It is said
that the motor vehicle produces 50% of man-made hydrocarbons, 60% of the carbon monoxide
and 40% of oxides of nitrogen. The modern approach is to reduce the exhaust emissions while still
retaining the maximum fuel efficiency from the engine.(UNITEC-4843 Theory Emissions pdf)
The four main gases looked at for emissions are Hydrocarbons, Carbon Monoxide, Carbon Dioxide and Oxygen


Because of this,regulations have been put into place to reduce emissions and motor vehicle manufacturers are required to follow these. These requirements include catalytic convertors which,without going under change itself converts gases emitted from the engine exhaust into more environmentally friendly gases, e.g carbon monoxide converted to carbon dioxide.

Oxygen Sensors which are mounted to the exhaust manifold calculate the amount of oxygen in the exhaust gases calculates the air-fuel ratio and passes this information to the ECU. Oxygen reacting with the ceramic material that makes up the sensor at high temperature. This what determines if the mixture is rich(low Oxygen,higher fuel) or lean(higher Oxygen,lower fuel).

Positive Crankcase Ventilation(PCV) which routes the gases back into the intake system and to the combustion chamber to burned up.It is a one-way valve placed in the valve

cover or side of the block. It is connected by a tube to engine vacuum at the base of the carburettor or intake manifold.

TESTING FOR EMISSIONS

we carried out emissions tests on a car with a carburetor and EFI. The 4 Gas Analyzer test measure the levels of the emitted gases after combustion.

the pictures were taken as the tests where carried out and the results for the Carburetor and EFI engines are listed after.

TESTING EMISSIONS ON A CAR WITH A CARBURETOR

ACTUAl before adjustment                                                    INDUSTRY STANDARD

H.C.        233 ppm                                                                       5 to 30    H.C ppm

C.O.       1.921 %                                                                    0.05 to 0.5   C.O %

CO₂       8.56 %                                                                         13 to 15.5   CO₂ %

O _{2          7.50} %                                                                        1.00 to 3.00   O ₂ %

Now test an EFI vehicle and record the results

ACTUAL                                                                               INDUSTRY STANDARD

H.C. 159 ppm                                                                           H.C 100 ppm

C.O. 0.720 %                                                                              C.O 0.300 %

CO₂ 14.07 %                                                                                        CO₂ %

O _{2 0.  83}  %                                                                                             O ₂ %