Focus piece: Waveform library
PicoScope Automotive includes a great feature that allows the Pico community to benefit from each other’s experiences. Under the File menu on the toolbar you will see Waveform Library Browser, this feature enables you to search and make use of a global database of waveforms uploaded by PicoScope users from around the world, and contribute yours to share with others.
The waveform library currently* has around 3900 reference waveforms you can use to help verify your own diagnosis. It is completely free to use for all PicoScope Automotive users.
To gain access to the library you need to have:
When you have logged in to the Waveform library, you can use a number of search options to find waveforms relevant to a specific manufacturer or model. You can also filter waveforms based on labels like “known good” or “known bad” which can give you an idea of the waveform pattern you are looking for and to compare directly with your own waveform. You can download the waveforms to open, view and use them as reference in PicoScope Automotive.
Information is key in our industry. End users need an understanding of how the sensor signals may look, as waveforms for different vehicle manufacturers and even models will differ.
We were called in to assist on a vehicle with a lack of acceleration which occasionally cut out at junctions, where the waveform library was invaluable in determining the fault:
The diagnostic fault codes pointed to a MAP Sensor fault, but that was not the whole story. Below is the waveform from the offending vehicle, and a donor waveform from the Wavefrom Library:
The reference waveform we downloaded from our waveform library showed a subtle difference in timing. The error was only ½ a crankshaft tooth which equates to a timing error of 3 degrees of crankshaft rotation.
With the rotation rulers in position, we used the time rulers to indicate not only the time, but the degrees of rotation as well.
The timing chain set was replaced and timing reset. A final check to the fix was a new capture of the cam and crank sensors, which verified the fix: