Most of us have a handle on how a combustible gas-powered engine operates, but a diesel engine's operation tends to be a little mysterious - we just know that they make a lot of smoke and a lot of clatter. Diesel-powered trucks are known for their incredible towing capability, which is a result of the engine's torque. Invented by German engineer Rudolph Diesel in 1892, these engines are also mostly four-stroke powerplants that burn fuel or oil instead of gasoline.
Diesel engines don't have spark plugs, they have glow plugs. You must turn the ignition key one click, then wait a few seconds for the glow plugs to get hot before you turn the engine over. During the first stroke, air is drawn into the combustion chamber through the intake valve - with no fuel. On the second stroke, the air is compressed and heated by the glow plugs. At the end of the compression stroke, vaporized fuel is injected into the combustion chamber and burns instantly due to the high temperature of the air in the chamber. This combustion will drive the piston back on the third - or power stroke - of the cycle. The fourth stroke is, of course, the exhaust stroke, purging gases out of the combustion chamber and cylinder. The speed and the power of the diesel is controlled by varying the amount of fuel that is injected into the cylinders.
In today's world of wild electronics and computers being inserted into our trucks, it is more of a challenge for aftermarket manufacturers to create components that enhance horsepower. Many modern diesel engines do not rely on mechanical pumps and are now electronically controlled by the truck's ECU (computer) system. With the advent of electronically controlled diesel engines, aftermarket engineers have been able to improve the engine's performance by re-programming its computer's parameters.
One of the latest is from Bully Dog Technologies in Aberdeen, Idaho. The company has a Can-Bus Pump Control (CPC) specially designed for the Dodge Ram Cummins 5.9 24-valve Turbo Diesel. The specialists at Bully Dog were kind enough to give us some background and a better understanding of the latest Cummins diesel built for the Dodge Ram, which uses an electronic control unit (ECU) to control the engine.
How It WorksThe ECU is designed to download different programs without having to make any physical changes to the engine. This unit will match the fuel delivery to a variety of operating parameters, such as engine temperature and boost pressure, as well as driver inputs. The driver input is indicated via the throttle position sensor (TPS), which controls the vehicle's acceleration. It uses these inputs to reference points from look-up tables - sometimes called maps - contained within the unit. From these, an end value is determined that represents the desired amount of diesel fuel to be delivered to the engine. The ECU, in turn, communicates the amount of fuel needed to the Bosch Diesel fuel pump. The pump uses a high-speed CAN-BUS data link that allows two-way information to be passed between the ECU and the Bosch pump. Essentially, they communicate with each other by using two wires. The Diesel pump has a mechanical section and an electronic section. The electronic section acts as an interface that converts information sent via the high-speed data link into mechanical actions. The pump sends information to the ECU regarding its current operating state.
The ECU directs the pump to achieve two main objectives. The first is to supply fuel to the engine in response to the accelerator pedal position when no boost is being produced. And second, to give additional fuel when boost is being produced. In a gasoline engine, when the throttle butterfly is opened, more air is gradually allowed to enter the engine. During full throttle, the air that enters the manifold passage into the engine is unrestricted because the throttle butterflies are wide open.
The throttle butterfly does not exist on a diesel engine, therefore there is no inlet restriction to air. This means that the engine operates with excess air all the time, because any boost pressure that is produced is transmitted to the engine. During idle, there is no boost pressure produced because there is not enough fuel entering the engine. When the throttle pedal is depressed, the fuel being delivered to the engine is increased. As the fuel is delivered, it will increase the boost to a level, which is only limited by the waste gate actuator setting of the turbocharger. To put it another way, the boost pressure in a diesel engine is dictated by the amount of fuel that is delivered and burnt by the engine.
The Bully Dog ApproachTo improve the Dodge Cummins diesel, the team at Bully Dog Technologies worked with Van Aken to develop and design an add-on computer that would fully integrate with the original equipment. The CPC plugs right into the original connectors and reacts to signals sent from both the Diesel Injection Pump and from the ECU. Controlled by a chip, the CPC uses advanced hardware and software to interact with that which is already installed on the Cummins engine.
The ECU that is used on the Cummins Turbo Diesel is bolted directly to the engine block and is permanently sealed shut in order to withstand the vibration, the heat, the dust, and the moisture in which it lives. Because it is sealed and cannot be opened, it is not compatible with conventional chip tuning, which relies on replacing a chip contained within the ECU. Fortunately, the manufacturers have left a margin for increasing horsepower and torque outputs, providing that means can be found to increase the amount of fuel that is delivered by the pump. The CPC does this by interrupting the messages that are sent between the ECU and the diesel injection pump and altering them to instruct the pump to deliver more fuel than standard when it is required.
The CPC will increase the power and the torque of the Cummins Turbo Diesel throughout the powerband. It can also vastly improve the driveability of the Cummins Diesel by giving it a massive boost and torque at low rpm. Its throttle response will become more rapid and noticeable. At 2,000 rpm, the power just seems to keep on pullin' with no stoppin'. Acceleration up hills is highly improved, and passing vehicles on the freeway is effortless
During towing, the power is most noticeable from the moment you hitch up your trailer. The installation of the CPC is a simple task, which can be accomplished in 10 minutes with a Dodge using a single battery. If the truck has dual batteries, it will take an extra 10 minutes. It is as easy to install the CPC as it is to unplug the electrical connection from the back of the diesel injection pump, then plug the CPC in between the pump and the electrical connector. To mount the CPC, locate a space on the fenderwell and use the two self-tapping screws. Now, you are ready for some true Bully Dog power!
There are three main components that make up an Electronically Controlled Turbo Diesel:1. Turbo charger2. Diesel fuel pump3. Electronic Control Unit (ECU)
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