PicoScope has recently released a new guided test for diesel engines

Modern diesel engines require quick and accurate diagnostics, and as complexity increases, so too does the diagnostic workload.
Workshops need fast and detailed evaluations of vehicle health to determine the next steps for repair, particularly when no obvious fault codes or symptoms are present.
Mount Auto Equip Services explains that Pico oscilloscopes and the guided tests allow technicians to build an immediate understanding of engine condition, often without needing any component disassembly.
By utilising the guided tests within the Pico7 software, the depth at which engine performance can be analysed quickly can significantly elevate a workshops diagnostic efficiency.
Pico has recently released a new guided test named ‘Diesel Engine Performance Test’ which is an in depth cylinder balance test.
Pico’s Diesel Engine Performance Test is specifically tailored for diesel diagnostics whilst running at idle and is an extremely comprehensive procedure to see how combustion effects the crankshaft speed.
In essence, by scoping the crankshaft sensor, camshaft sensor, and fuel rail pressure sensor, users can observe in fine detail the increase or decrease in speed each cylinder has on the crankshaft, and therefore the engine’s overall performance.
The process begins by capturing the crankshaft position sensor waveform. Once displayed, Pico’s phase ruler function (a highlighted segmentation based on the number of cylinders) identifies individual cylinder events and reveals crankshaft speed variation.
Further insight is provided by using Pico’s math channels: by selecting the correct crankshaft pre-defined math channel, the software calculates engine RPM directly from the crank signal.
Combined with the phasing channel, this allows the technician to accurately assess cylinder contribution, idle stability, and other performance anomalies in great detail.
Mount Auto Equip Services explains that in effect, this functions as a highly detailed cylinder balance test, applicable to virtually any diesel engine.
From here, additional measurements can expand the diagnostic results further.
Introducing a camshaft sensor signal, along with knowledge of firing order, enables identification of which cylinders may be responsible for imbalance or poor performance.
Cylinder identification could also be achieved by introducing an injector current signal; however, the camshaft signal provides the additional benefit of enabling a cam/crank correlation reference to confirm engine timing, further enhancing the accuracy and confidence of the diagnosis, says Mount Auto Equip Services.
When adding waveform data from the fuel rail pressure sensor, the system can also quickly reveal abnormalities in fuel delivery based on injection.
For example, fuel rail pressure should remain stable at idle indicating even fuel delivery by each injector.
Excessive fluctuations or higher or lower pressure events accompanied by declining crankshaft speed may indicate an injection issue.
If this coincides with a slow down of the crank speed, users can use the cylinder identification to direct them to the cylinder to look at first.
By using this approach, the entire test can be performed by probing only three sensors, often without any disassembly depending on engine layout.
Mount Auto Equip Services says in today’s modern workshop environment, having access to this level of equipment greatly improves diesel diagnostic accuracy and reduces downtime.
You can add more detail to this test with a fourth channel by using the WPS500 pressure transducer connected to the exhaust or low pressure fuel line using the same time base providing an almost complete picture of engine health.

For more information, contact Mount Auto Equip Services 02 9905 8055 or sales@maeservices.com.au or visit www.autoequipment.com.au