Comprehensive diagnostics of diesel engines

Autoscope Technology provide a comprehensive set of tools and scripts that enable technicians to quickly and accurately identify diesel engine problems.
This article explores key diagnostic methods using USB Autoscope, including the ElPower script for analyzing hard engine starting, CSS script for cylinder balance testing, camshaft-crankshaft synchronization tests, and in-depth injector waveform diagnostics.
Additionally, it covers advanced techniques such as analyzing cylinder pressure graph with the PSG200 diesel pressure sensor, using specialized adapters, and testing mechanical injection systems with the PD-6 piezo transducer. Together, these tools form a powerful approach to diesel diagnostics in both workshop and field settings. This script is used at many car service stations to analyze hard starting problem of a diesel engine at any time of the year.

This is especially relevant at low temperatures below 0 °C.

Within 3-5 minutes, you can check the characteristics and condition of:

• battery
• alternator
• starter
• glow plugs
• relative compression in engine cylinders

To perform the test, you need two signals:

• battery voltage
• current consumption measured using the CTi-1000 current clamp

Yellow background - measured parameters deviate from the norm.
Red background - measured parameters are outside the norm.
The report of the online version of the ElPower script algorithm may display the "Compression" tab This test is simple and fast, without disassembling the engine and its systems, it identifies cylinders that are misfiring and indicates the area of origin of the malfunction.
The express diagnostics time does not exceed 3-5 minutes. To test the CSS of modern cars, signals from the crankshaft position sensor and the injector control pulse are required.
There are two types of crankshaft position sensor: Hall sensor and inductive.
The injector control pulse can be measured using the CTi-50 current clamps. In a short time, you can check:

• condition of a fuel injection system (uniformity of fuel injector operation)
• condition of the mechanical system of a diesel engine (filling the cylinders of an internal combustion engine with an air-fuel mixture)
• evaluate static and dynamic compression in the cylinders
• Detect faults in the diesel engine timing mechanism

3. Testing the engine synchronization between Camshaft and Crankshaft sensors and diagnosing engine valve timingThese measurements are necessary if the engine cannot be started. These are the main signals for the control unit of a modern car. Both Crankshaft sensor and Camshaft sensor signals are present. There is no control of the fuel injectors.
The presence of these signals and their correct synchronization are the main ones for the ECU in controlling the fuel injection pulse. Video In many manuals, manufacturers provide reference signals for each specific engine. Some of this information is on the website:  forum.injectorservice.com.ua This information is useful in case of replacement (or repair) of diesel injectors and their reprogramming. To do this, it is necessary to attach  CTi-50 current clamps  to the control pulse wire on the injector connector.  It should be noted that the design of the measuring part of the CTi-50 current transducer is specially made for such measurements. Video The duration of the injection pulse can be used for estimation the injection corrections in the control unit. Here are shown the control signals of faulty injectors.
It is clear that there is a correction for fuel injection (different pulse durations). Control signal after replacement with new injectors. Minimal signal correction.
Control pulses of injector manufacturers Bosch, Denso, Delphi:
 

The pressure graph in the cylinders of a running diesel engine was, until recently, impossible for service center technicians. Standard pressure sensors are not designed for such measurements. A solution to this problem was proposed by BERU. They developed new glow plugs with built-in PSG pressure sensors. PSG200 pressure sensor  waveforms provide valuable data for identifying complex faults in diesel engines. In addition, they help technicians gain a deeper understanding of the processes occurring in the engine cylinder, which allows for faster and more accurate diagnostics. Using four diesel engine pressure sensors allows estimating the contribution / balance of all cylinders simultaneously. The resulting pressure graphs contain information about the combustion process of the fuel mixture, which depends on:

• Engine temperature
• Compression ratio
• Compression
• Fuel atomization quality
• Correct positioning of the injector nozzle in the combustion chamber

Each sensor must have its own amplifier.  Article  about the examples of diesel pressure transducer use.
As a result, technician has the opportunity to see and compare pressure graphs in the cylinders of a running engine.  To work with the pressure sensor, it is necessary to use special adapters:  These  adapters  must be installed in place of the glow plugs.  For a high-quality analysis of the pressure graph, it is necessary to install the sensor as close as possible to the combustion chamber.