Top 5 Common Diesel Engine Issues & Prevention - Part 2
Injector Problems
The fuel injection system is the heart of any diesel engine, responsible for delivering the precise amount of fuel needed to ensure efficient combustion. Modern diesel engines rely heavily on advanced injection systems that operate at extremely high pressures and precision levels, but with that complexity comes a range of potential issues. Understanding how these injectors work, what causes them to fail, and how to maintain and prevent problems can go a long way in ensuring the longevity of your diesel engine.
A) Modern Injector Description
Modern common rail injectors can be broken down into two main types: Coil (Solenoid) Injectors and Piezo Injectors.
- Coil (Solenoid) Injectors: These are the more traditional type of injector. They use a solenoid valve to control the fuel injection process, making them more robust from an electrical perspective. Although they are not as precise as piezo injectors, they tend to be more tolerant of electrical issues and are slightly easier to diagnose and repair in case of failure
- Piezo Injectors: Piezo injectors operate with greater precision and faster response times than solenoid injectors. They use piezoelectric materials that expand or contract when an electrical current is applied, allowing them to inject fuel more rapidly and with better control. This results in improved fuel efficiency and cleaner emissions. However, piezo injectors are more sensitive and prone to electrical errors, which can sometimes lead to injector failure
Both types of injectors operate under extreme conditions, with pressures ranging from 1,600 to 2,200 bar, and each injector firing fuel 2 to 5 times per combustion cycle. This means that injectors are constantly working, making them susceptible to wear and tear, especially when subjected to poor-quality fuel
B) Common Failure Modes
While modern injectors can last for many years or even the lifetime of the vehicle under ideal conditions, real-world factors like poor fuel quality can significantly reduce their lifespan. The most common injector failure modes include:
- Seizure and Wear: One of the most frequent issues with common rail injectors is internal wear and scoring due to contaminants in the fuel. Dirt, water, or other impurities can create friction inside the injector, leading to seizure. Scoring marks on the internal components are a telltale sign of this problem, often resulting in injector failure.
- Electrical Failures: Piezo injectors, while offering more precision, are more prone to electrical issues. Faulty connections, power surges, or internal electronic malfunctions can cause injectors to misfire or fail completely
- Poor Atomization: Over time, injectors can become clogged or worn, leading to poor atomization of the fuel. This can result in rough idling, increased emissions, and lower fuel efficiency.
- Overfueling or Underfueling: Damaged injectors may leak fuel or fail to inject the correct amount of fuel, which can cause overfueling (leading to black smoke and excessive emissions) or underfueling (resulting in poor engine performance and misfires)
C) Injection System Maintenance
Proper maintenance of the fuel injection system is essential to avoid costly repairs and keep your engine running efficiently. Key maintenance tasks include:
- Fuel Filters: Regularly replacing fuel filters is critical for maintaining injector health. Diesel fuel, especially in countries with lower fuel standards, is prone to contamination. Fuel filters help trap dirt, water, and other impurities before they reach the injectors. Changing filters according to manufacturer guidelines, or more frequently in harsh conditions, is essential to prevent wear on injectors
- Suction Control Valve (SCV) Maintenance: The SCV is one of the hardest-working components in the fuel system, regulating the amount of fuel entering the high-pressure pump. It wears down over time and is one of the most common failure points in the system. Replacing the SCV periodically can prevent strain on injectors and improve overall system efficiency
- Fuel System Cleaning: Periodically using fuel system cleaners can help reduce the build-up of carbon deposits and prevent clogging in injectors, improving their lifespan and maintaining fuel efficiency.
D) Prevention Options
Preventing injector problems involves several strategies, most of which revolve around maintaining fuel quality and ensuring proper system care:
- Fuel Quality: As discussed in Section 1, the quality of diesel fuel plays a huge role in injector health. Always purchase fuel from reputable stations, and avoid filling up when the station is receiving a delivery to minimise contamination
- Fuel Filters: Regularly change your fuel filters and consider installing a secondary filter to capture finer particles that might bypass the factory-installed filter. This can help reduce the strain on your injectors and prevent internal wear
- Lubricity Additives: In regions where diesel fuel has low lubricity, adding fuel additives can help protect injectors from wear. Some diesel owners, particularly those without Diesel Particulate Filters (DPFs), use 2-stroke oil as a lubricity enhancer. However, this should never be used in vehicles with DPFs, as it can lead to clogging
- Upgraded Injectors: For more extreme conditions or performance-focused builds, Diamond-Like Carbon (DLC) injectors offer greater durability and resistance to wear. These injectors can be a valuable upgrade for those looking to enhance the longevity of their fuel systems in harsh environments
By understanding the intricacies of modern fuel injection systems and taking the right preventative measures, you can significantly extend the life of your injectors and maintain the efficiency of your diesel engine for many years to come.