PicoScope 7 Automotive
Available for Windows, Mac, and Linux, the next evolution of our diagnostic scope software is now available.
The sensors seem to work fine with the engine off - no noise. But I'm interested in what happens when the engine is running. If the sensors are fine but something is causing interference with the sensor signal and causing the computer to read incorrect values, I want to find out, and fix it.Technician wrote: ↑Thu May 14, 2020 7:21 pmDo you need the engine running to test the TPS and Vane Air Flow meter?
With the ignition on manually test the sensors and see if noise is still present.
Thanks. I'm not sure what you mean by "mass" though. Could you clarify that?vasek wrote: ↑Thu May 14, 2020 9:23 pmHi.
The noise that is present in the signals does not affect the problem with the engine operation in your example.
Such noises may be caused, as indicated above, the operation of the generator, drives the coils and injectors, fuel pump, electric motors, etc.
To more precisely, you need the file itself, not just images of fragments.
If there is a file, you can measure the noise frequency and relate it to the frequency of electronic components in the control engine.
In addition, the presence or absence of this type of noise depends largely on where the oscilloscope is connected to the mass.
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The ECU does not receive such interference to the signal, since it uses the mass of the signal from the sensors.
You can also change the connection point of the oscilloscope to the hardware mass.
The signal will immediately become much cleaner.
You will calm down, and immediately start looking for the problem in another place (spark generation system, fuel supply, air boost stability, and so on).
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If you connect the mass to the negative terminal of a battery, the noise can be very strong in amplitude.
If you connect the mass of the oscilloscope to the mass of the sensors, the signal will be noise-free.
For example,compare two signals that are taken from the same engine,but the mass is connected at different points.
Mass - ground (machine translation ).
Connect the oscilloscope ground to ECU sensor ground.
If you are sure that spark formation is all right, you need to look for the reason for sporadic lean mixture at a partial load.
OK maybe this is a stupid question, but I don't think I really understand what "sensor ground" means. This ECU has one common ground reference for all sensors (for all sensors that have a ground; some don't). These ground pins are all connected together (I just checked with an ohmmeter on a spare ECU). When I connected my scope, I connected it to one of these pins. I didn't think it mattered which one, since there is nothing between them except a few centimetres of copper trace.vasek wrote: ↑Thu May 14, 2020 9:52 pmMass - ground (machine translation ).
Already corrected it.Connect the oscilloscope ground to ECU sensor ground.If you are sure that spark formation is all right, you need to look for the reason for sporadic lean mixture at a partial load.
And this - is not noise on the sensors signal.