WS3B LAB SCOPE

MAP sensor pattern against injectors pattern allows comparing the engine load relationship with injectors open time. With higher load injectors duration is getting longer. This is how the ECU adjusts the amount of fuel delivered via injectors. Duty cycle of injectors can be observed correspondingly to the MAP sensor signal.

Where: Vcc-voltage supply for injectors
             T-time for which injector is grounded and fuel is sprayed into the cylinder
             V peak- induced voltage after the injector is disconnected from earth
Having no opportunity to adjust frequency division independently for each channel we could not captured changes in the progress on one photo. There are several photos below which illustrrate that frequency of injectors been opened changed with increase in load.

Oxysensor against injectors.

The idea of this experiment is to watch that the more fuel is injected under load the richer mixture is sprayed into the cylinders. Oxysensor registers these changes thanks to higher level of oxygen flow. It sends the ECU the signal that mixture is rich at the moment. This is how closed loop acts.
 

Primary ignition patterns against injectors.

This comparison expresses close relationship between the two: injection and ignition. At the higher RPM injectors are opened more often and ignition occurs accordingly. These processes go
synchronously. If discrepancy takes place the engine will not run smoothly, misfire is possible or in the heavy cases engine will stall.


 RPM SIGNAL (INDUCTIVE TYPE) AGAINST INJECTORS

NE pick-up stands for number of engine revolutions. The oscilloscope pattern above shows that with RPM increase the injectors’ frequency goes up. Injectors are opened faster and their duty cycle rises. Dynamics of these processes can be analysed in order to determine what is the fault if it takes place.

Ignition primary voltage against ignition primary current

As it seen from the pattern we captured current rises in linear proportinon while the primary circuit is completed. At the moment the igniter is disconnected form ground and magnetic field in the coil collapses current fells down instantly. This failing path of the pattern is smooth, no fluctuations. It's very important and tells us that coil and igniter function correctly. There are no looses due to poor circuit elements conditions or ground problems. The attenuator has been used to convert the measurements from voltage into the current. Having knowing ratio between the two we can calculate what is the current flow in the primary circuit. In this case it's 4 amps. The analysis of both current and voltage brings more information of circuit functioning.