Off car fuel injection testing

The fuel injectors are usually mounted on the intake manifold but some engines have the injections injecting directly into the cylinders. The injectors along with the ECU, fuel pump and fuel regulator controls the amount of fuel that is injected into the cylinders. In an injector there is a needle that is controlled by a solenoid, when the solenoid receives power it pulls the needle back allowing fuel to go into the cylinders and if the power is off the needle moves forward again blocking the fuel entering the cylinders. The injectors are opened and closed by the ECU sending it power accordingly to the engine timing.

Experiment


We did a off car injector test using an injector tester. We connected the four injectors in the tester and switched on the machine. We did a flow test to check that the injectors have the correct spray pattern. Then we did a normal function test to see if the injectors opened and closed correctly and if they functioned at higher RPMs. The last test we did was the hold test to see if the injectors would leak if they were closed.

Reflection


The injectors are cleaned in a ultra sonic bath to loosen any carbon or debris in the injectors then it is washed out by back washing it. If a injector has a irregular spray pattern it needs to be clean or replaced because if it does not spray correctly some of the atomized fuel will condense in the intake manifold instead of going into the cylinder which means there is less fuel in the cylinders to burn and that causes the engine to run lean. If a injector leaks when it is off the pressure in the fuel rail will drop, this means that the injector that is opened will have less fuel passing through it cause the engine to run leaner. The fuel that leaks into the intake manifold will condenses on the sides and will not burn properly when the intake valve is opened this creates more pollution due to the higher amount of unburnt fuel (HC) coming out of the exhaust and it reduces the fuel economy. It also drains the fuel in the fuel rail when the car is off causing the car to take longer to start and it wastes fuel.