[G-scan] Japanese Commercial Truck Training Video_Chapter 1

[G-scan] Japanese Commercial Truck Training Video_Chapter 1


Hello all G-scan users! I’m Jason and I’m a technical supporter. Our G-scan team came to Japan to shoot the training videos on Japanese commercial trucks. We are here at Service yard of KANTOKU company located at Sano city in Japan. As you can see, these are Japanese diesel trucks. Isuzu, Hino, UD, and Mitsubishi Fuso. Special thanks to KANTOKU company for all the supports. KANTOKU company is a 2nd hand Japanese Domestic Manufactured truck exporter and our strategic partner who is always supportive in our G-scan development. This video contains 5 chapters. In chapter 1, I’m going to talk about diesel engine and Particulate matter reduction system. From chapter 2 to chapter 5, Isuzu, Hino, Mitsubishi Fuso, and UD trucks will be discussed. I’m going to show you their data link connector locations, and special adapters. I’m going to show you some basic diagnosis technique using G-scan. Also vehicle type selection on G-scan and some special functions will be discussed. I hope you enjoy the video. Let’s begin with chapter 1.   In chapter one, I’m going to discuss mainly on common rail system and Diesel particulate matter reduction system. Before we get into the common rail system, let’s talk about a little bit of background for better understanding of why the common rail system has been introduced. Diesel engines, unlike gasoline engines, do not have spark ignition system. Combustion occurs due to the heat produced from compression of air that raises the temperature of the air/fuel mixture to its auto ignition point. Depending on the design, the ratio ranges between 15:1 and 23:1, or even higher. In order for the diesel engine to ignite the fuel, what it needs is highly compressed air and right amount of fuel at the right time. As compressed air is always present, fuel delivery is the key factor in the diesel engine system. First introduced diesel engine had no electrical system regarding fuel control. Fuel volume was controlled by a plunger type pump which rotates only a few degrees releasing the pressure and was controlled by a mechanical governor which limits the maximum and idling speed of the engine by controlling the rate of fuel delivery. The mechanical governor is driven by crankshaft or camshaft and its speed was dependent on engine speed. As the governor spins faster, the lever moves out due to the centrifugal force. When the lever is extended, it mechanically limits the fuel flow to the engine. Now, here comes the problem of this old diesel engine with plunger type pump with mechanical governor. In terms of performance, maintaining the engine speed with high load was not pretty. With high load, engine needed more fuel to produce more power. As the governor speed is proportional to the engine speed and it only controls the fuel flow, it could not compensate very well for variations in fuel delivery. Moreover, plunger type pump was constantly out of adjustment due to the inevitable vibration caused during the engine operation. In terms of emission, diesel exhaust smoke was a serious source for air pollution. Plunger type pump pressurized fuel between only 120 bar ~ 350 bar and that pressurized fuel was injected through nozzles. But, injected fuel was pressurized to such a level that the fuel particle was too large; complete combustion was impossible to achieve. It caused heavy black smoke out of diesel exhaust pipe. Later on, a mechanical single plunger high pressure pump with electro-magnetically controlled governor was introduced. Under the control of ECU, it seemed to solve the previous problem. However, the result was not satisfied. Shortly after, under pressures of strict emission regulations and competitions among manufacturers for developing better technology, manufacturers strived to develop better diesel fuel control system that has better performance, better fuel economy, and cleaner emission. The new system had to precisely control pressure of the fuel, fuel injection timing, and quantity. The common rail system can be divided into 3 areas: sensors, actuators and engine ECU. There are many sensors related to the Common rail system such as Engine speed sensor, accelerator position sensor, Camshaft Position sensor, Crankshaft Positions sensor, fuel pressure sensor and more. The engine ECU receives data from these sensors and calculates the proper injection quantity and injection timing for optimal engine operation. Then, ECU commands actuators into action. Some models might have another extra control unit for injectors, called EDU (Electronic Drive Unit). EDU serves the same function as the ECU, controlling injection quantity and timing for best engine operation. Actuators are SCV which is suction control valve on Supply pump, injectors, pressure discharge valve on common rail and so on. For your information, Suction control valve controls the quantity of fuel that is supplied to the supply pump in order to control fuel pressure in the common rail. Remember, the old mechanical plunger type pump produced not enough pressure to achieve complete combustion of air/fuel mixture. However, with ECU controlled supply pump and highly pressurized common rail system, it was possible to atomize fine fuel particles, and thus, big improvement in exhaust emission could be achieved. The common rail system stores fuel in the common rail, which has been pressurized and supplied by the supply pump. Injectors are equipped with electronically controlled solenoid or piezo type valves to inject the pressurized fuel into the cylinders. Because the engine ECU controls the injection system (including injection rate, injection pressure, and injection timing), the injection system is unaffected by the engine speed or load. So, the engine ECU can control injection quantity and timing to a high level of precision and even multiple fuel injection is possible. Common rail system ensures a stable injection pressure at all times, even in the low engine speed range. As a result, it is possible to not only reducing the amount of black smoke emitted by ordinary diesel engine during cold start and acceleration, but also achieving high engine output. Emission regulations are getting stricter ever due to serious worldwide air pollution. Under emission regulations such as EPA (Environmental Protection Agency) in the United States or Euro 4, 5, and 6 in Europe, there is another system that diesel engine manufacturers have been strived to reduce the diesel emission. Under both regulations, Particulate Matter value must be met stunningly low 0.01~0.02 g/kWh, which could not be achieved by improving fuel efficiency. To reach those emission levels, manufacturers are adding diesel particulate filters into the exhaust system to reduce Particulate Matters produced during the diesel combustion process. Each manufacturer has different name for the system. For example, Mitsubishi Fuso calls it “DPF (Diesel Particulate Filter)”, Isuzu calls it “DPD (Diesel Particulate Diffuser)” and Hino calls it “DPR (Diesel Particulate active Reduction)”. As for UD, since some of their vehicles share the Hino and Fuso’s system, they have both “DPR” and “DPF”. It may sound different system, however, they are working on the same target, reducing the soot captured in the filter. Here’s how it works. A Diesel Particulate Filter (DPF) is usually made of silicon carbide core encased in a steel shell. It is located in-line with the exhaust pipe on most diesel engines manufactured since 2007. As the exhaust gas is forced through the filters, particulate matter or “soot” is trapped inside. Before and after the DPF, differential pressure sensors and temperature sensors are located for the purpose of monitoring DPF operation. Differential pressure sensors monitor pressure difference between pre and post DPF. If DPF is clogged due to captured soot, pre and post DPF pressure in the exhaust must be different. Once ECU notices the difference, it triggers the DPF warning light. In case of driving on the highway, the exhaust reaches high temperatures and the trapped “soot” is automatically burned up. This process happens automatically during the operation and without drivers knowing about it. However, trucks sometimes have to run at low speed where DPF cannot meet high enough temperatures to burn down captured Particulate Matters. This is where you have to use a scan tool to manually burn down the PM. You can perform forced DPF regeneration using our G-scan in order to burn down all those captured particulate matters inside the DPF system. In the process of DPF regeneration, ECU commands injectors for extra injection (a.k.a post injection) after main injection to raise the exhaust temperature at least 500 degrees Celsius. Then, ECU monitors temperature sensor located before the DPF, to check whether desired temperature is met or not. Other than DPF system, there is a SCR (Selective Catalytic Reduction) system. This technology is another advanced emission control system that injects special Diesel Exhaust fluid (Urea, AdBlue) through a special catalyst into the exhaust stream of a diesel engine. SCR can effectively reduce NOx emission while simultaneously reducing HC, PM and CO emission. SCR systems can also be combined with a diesel particulate filter to achieve even greater emission reductions for PM. Let’s sum up some of the key points in chapter 1. I talked about a bit of history how common rail system came out in the market. There were some problems manufacturers faced with plunger type pump system, emission was severe concern. Under such strict emission regulations, manufacturers had to develop such system that would satisfy the regulation standards and Common rail and DPF system was introduced. The mainstream diesel technology is in fact, common rail and Diesel Particulate filtering system. Understanding these systems definitely helps you when you diagnose such vehicle equipped with these systems. Let’s see what we can do with G-scan on diesel trucks in following chapters.