The earlier Toyota 1VD engines, primarily in the pre-DPF models, use solenoid-controlled injectors. These injectors have been around for years and are well-known for their robust design. However, they come with certain limitations when faced with Australia’s tough conditions, particularly in extreme heat, dust, and poor fuel quality environments.
Solenoid injectors rely on a magnetic coil to control fuel injection, opening and closing to regulate fuel delivery. While this is a time-tested technology, the larger internal moving parts can present challenges over time, particularly in conditions where contaminants or low-quality fuel are present.
Robust Electronics: Solenoid injectors are highly reliable from an electronic perspective. The coil system that controls the injectors is simple and less prone to electrical failures, which means solenoid injectors have a longer lifespan when it comes to electrical components.
Cold Knock Symptoms: Solenoid injectors are also known for causing what is commonly referred to as "Toyota Cold Knock." This happens when the injectors struggle to deliver fuel efficiently during cold starts, leading to a knocking noise that fades as the engine warms up. It’s a well-documented problem in the 1VD engine, and timely injector maintenance and replacement can prevent further damage.
Monitoring for Symptoms: Early detection is key to preventing severe injector damage. Regularly check for signs such as rough idling, reduced fuel economy, or unusual knocking sounds. Monitoring injector feedback values as part of your routine maintenance can help identify issues early.
With the introduction of the DPF (Diesel Particulate Filter) system, Toyota upgraded the 1VD engine to piezo-electric injectors. These are far more advanced and precise compared to solenoid injectors, but they come with their own set of challenges. Australian conditions can expose these injectors to unique failure modes, especially when fuel quality is inconsistent.
Piezo injectors use a piezoelectric crystal to control fuel delivery, allowing for incredibly precise injections with multiple deliveries per combustion cycle. While this provides improved efficiency and emissions control, the technology is more sensitive to fuel quality and operating conditions.
Precise Fuel Delivery: These injectors are more accurate than solenoid injectors, which results in smoother engine operation, better fuel efficiency, and reduced noise. The piezo system also helps meet the stricter emissions standards required by DPF-equipped engines.
New Failure Modes: While piezo injectors have addressed some of the limitations of solenoid injectors, they have introduced new failure modes that differ between the 70 Series and the 200 Series Land Cruisers:
Interestingly, both the 70 and 200 Series share identical fuel systems and injectors, but these failures have been prevalent enough that Toyota Australia has struggled to meet the demand for injector replacements under warranty claims. At one point, it became difficult to purchase a complete set of 8 injectors in Australia, and Toyota required VIN numbers just to supply one or two injectors.
Part Supply Challenges: Injector supply in Australia is still relatively tight due to high demand for replacements. However, Diesel Geeks sources parts from Denso distributors around the world, ensuring that we are less susceptible to local supply shortages.
Regular Injector Testing: Due to the advanced design of piezo injectors, regular testing is recommended to catch issues early. Look out for early warning signs like reduced power or fuel efficiency. For 70 Series owners, prompt action on P1238 codes can prevent further damage, while 200 Series owners should monitor for excessive smoke.