PDS Pressure drop sensor
17$
The sensor is meant for recording the forms of pressure pulsations in the intake manifold, crank case ventilation system or engine exhaust system. This allows estimating alignment accuracy of the value train, checking cylinder balance as well as detecting misfiring without taking an engine apart.

Key Features

Manufacturer

ROTKEE (Ukraine)

Pressure Medium

gas

Pressure Ranges

-100 to 100 kPа

Overload Pressure

150 kPа

Output connector

Supply voltage

not provided

Output Signal Type

analog

Operating temperature range

-20 to 80℃

Output Signal

-5 to 5 V

Weight

Recommended Sampling Rate

not less than 10 kHz

Signal Cable Length

2.5 m

Housing Material

polyamide

Photo

Waveforms

 

 

Contents of delivery

  • PDS depression sensor - 1 pc
PDS pressure drop sensor contents delivery

Video Lessons

Diagnosing a valve timing with the help of a pressure drop sensor and automotive oscilloscope, connecting the sensor to the engine, oscilloscope tuning, oscillogram recording while idle running and cranking. We’ll demonstrate all of this with an example of Subaru Impreza.

The Sensor Design

Sensor case is made of polyamide, which makes it heat-proof and resistant to deleterious substances while being tough and light. Sensor’s connecting tube is made of brass and can to be connected to rubber tubes between 4-7 millimetres in inner diameter. A soft microphone cable with thick braided screen is used as a cord. BNC is used as a sensor-oscillograph connector.

Under sensor development high emphasis has been placed on cable and case joint as this junction is error-prone. This solid joint prevents cable breakdown and increases its durability.

The sensor consists of a film with piezoelectric crystal plate, which interacts with the pressure in the measurable area. As the pressure rises, the plate bends. When the pressure is back to normal, the plate resumes its shape. As piezoelectric materials produce an electric charge while undergoing deformation, electric voltage occurs on the surface of the plate, which is virtually proportional to the material pressure.

One of the sensor’s features is that it can be used for displaying dynamic pressure. It can’t measure static pressure, because as soon as pressure becomes static, piezoelectric ceramics ceases to deform and therefore stops producing electric charge. Meanwhile, the charge stored on the plate bleeds to zero in the material or meter. In practice it makes no difference to diagnostics though, as while an engine is working, the pressure constantly changes in all systems indicated. Using piezoelectric ceramics as a measuring element allows significantly reducing sensor’s price without affecting measuring accuracy. Another advantage is that there’s no need to use an external power source. This is what makes this technique universal and able to be used on any internal combustion engine, as depression sensor requires no tuning control while in use.

The sensor was developed as compatible with MT Pro automotive oscilloscope as well as any other oscilloscope, analog channel.

Diagnostic Technique

While working an engine produces a series of pressure pulsations in intake and exhaust manifolds. This happens because intake and exhaust valves open and close in a certain sequence, redistributing the streams of fuel air mixture and exhaust fumes. Every time an exhaust valve opens and burnt gases come out of the combustion chamber, there’s a high-pressure pulse in the exhaust system. Procedure of similar nature takes place in the intake manifold as well. A lot can be inferred from the pressure in the crank case. Pressure pulsations in there indicate blow-by past the piston rings. The pressure is measured by mounting the sensor to the oil level indicator tube.

PDS pressure drop sensor diagnostic technique

In all cases pressure oscillograms display events taking place during all working cycles of a four-stroke engine. In a perfect engine pressure pulsations look the same and correspond to a certain pattern, which can be displayed with the help of a depression sensor and oscillograph. Any deviation of the signal waveform from the standard implies a certain malfunction.