Px40 pressure transducer
The Px40 in-cylinder pressure transducer is used for testing of petrol engine mechanical faults using an oscilloscope. Px40 allows you to perform quick cylinder pressure diagnostics and obtain an accurate pressure analysis in a range of −0.9 to +45.5 Bar (−13 to 660 psi). The Px40 is designed to work with the USB Autoscope IV oscilloscope as well as with other oscilloscope models.
Featuring a modern design, the Px40 pressure sensor is housed in a durable stainless-steel case that ensures long service life in demanding workshop environments. Its compact form factor, extended pressure measurement capability of up to 40 Bar, and enhanced sensitivity make the Px40 a powerful and convenient solution for advanced engine diagnostics.
The Px40 is robust high-resolution pressure sensor that enables precise visualization of in-cylinder pressure waveforms directly on the screen of an automotive oscilloscope.
Px40 is a new and updated version of our pressure sensor for in-cylinder pressure measurement of gasoline engine, it is our proven industry-leading pressure sensor for automotive diagnostics.
The Px40 pressure transducer is designed to diagnose the condition of the engine mechanical condition using an oscilloscope. It allows you to display on the screen of an oscilloscope a waveform of the pressure in the cylinder of an engine operating on:
- Gasoline
- Liquefied gas
- Compressed gas
- Alcohol-based biofuel
The pressure sensor is installed in place of the spark plug. During measurements, it is necessary to disable combustion in the tested cylinder by disconnecting the ignition spark in the tested cylinder. For this purpose, the high-voltage lead of the tested cylinder must be connected to a Spark Gap tester.
If the ignition coils are mounted directly on the spark plugs (Coil-On-Plug or ignition coil modules), will be additionally required one or more Adapter for high voltage extension cable and Ignition wire kit.
If the engine is equipped with two spark plugs per cylinder, the second high-voltage lead of the tested cylinder must be connected to an additional spark gap tester to prevent ignition in the cylinder to which the pressure sensor is connected.
The Px script report contains key cylinder characteristics and allows you to:
- Evaluate the condition of the cylinder–piston group
- Measure the compression ratio
- Check cylinder sealing and detect air leaks from the combustion chamber
- Measure the actual valve timing
- Verify the operation of all intake system components, such as the turbocharger, VVT, VTEC, Valvetronic and similar systems, intake manifold geometry control systems, and intake resonators
- Measure exhaust system flow resistance (catalytic converter, resonator, muffler, exhaust pipe);
- Measure the actual ignition advance angle
Px40 pressure sensor works with an automotive and lab scopes equipped with BNC connector. For this, you need to use XLR-BNC connection cable
The USB Autoscope software automatically analyzes the cylinder pressure waveform. The result of the analysis is presented in an easy-to-understand form. The analysis algorithm is called Test Px.
Px Test is the intellectual property of Autoscope Technology. All rights are reserved.
| Measured pressure range | -0.9…+45.5 Bar |
|---|---|
| Sensitivity | 121 mV / Bar |
| Output voltage range | 0.26…5.9 V |
| Formula (relative pressure, Bar) | P = 8.2463156⋅U-3.0509434 |
| Formula (absolute pressure, Bar) | P = 8.2463156⋅U-2.0509434 |
| Formula (relative pressure, PSI) | P = 119.6026978⋅U−44.2501936 |
| Formula (absolute pressure, PSI) | P = 119.6026978⋅U−29.7464196 |
| Voltage at 1000 mBar (750 mmHg) | 370 mV |
| Response time | < 1 ms |
| Max measurement duration | < 3 min |
| Working temperature range | -40...+125 °C |
| Supply voltage | 10…15 V |
| Current consumption | < 10 mA |
| Inlet thread size | M14 x 1.25 Male (standard spark plug thread) |
| Output connector type | XLR MALE |
| Output connector pinout | 1: Output, 2: GND, 3: +12V |
| Diameter | 24 mm |
| Length | 87 mm |
| Weight | 140 g |
Specific points and sections of the in-cylinder pressure waveform of a gasoline engine operating at idle speed. In this form, the waveform can be obtained using any oscilloscope. However, a lot of knowledge and time is needed to properly analyze its characteristic points.
The USB Autoscope software automatically marks the specific points of the cylinder pressure waveform, displays a mask of their permissible positions, as well as the actual value of the deviation from the norm.
For detailed analysis of the cylinder pressure waveform, including in transient engine operating modes, the USB Autoscope software is equipped with the Px script. The script displays the results of the analysis in the form of a detailed and visual report.
It takes only 30 ... 40 seconds to complete the Px test.
The script automatically measures and analyzes the key characteristics of the cylinder, intake and exhaust system, the valve timing mechanism and the ignition timing control system, and provides: - automatic measurement of real valve timing; - assessment of the degree of compression and leakage of the cylinders; - checking the exhaust system; - diagnostics of fixed and variable intake systems, turbo and superchargers, VVT, Vanos, and VTEC systems. - check the ignition timing system.
| Timing phases are set incorrectly | Timing phases are set correctly |
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| Clogged catalyst | Catalyst replaced |
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