It is quite common to transition from driving a petrol combustion engine car to a diesel vehicle
and feel as though you have just bought an underpowered car.
Long-time diesel owners might disagree, as there have been substantial improvements since the introduction of the first Gemini diesel car in Australia during the 1980s.
For some individuals, the existing power is not enough, or they believe they can achieve greater economy. As a result, they explore options to enhance the power output of their newly acquired diesel.
While performance upgrades are common, they should be approached with caution. Anyone can reprogram a vehicle's computer, but do they have adequate experience on diesels to unleash significant power without damaging the engine? Increasing power beyond manufacturer specifications increases stress on engine components and can reduce long-term reliability.
There’s room for upgrades, just don’t expect a diesel to perform like a petrol engine car.
If you are a first-time diesel owner coming from a higher-performing petrol engine, it may take some time to adapt to a diesel’s unique performance characteristics. Between the two types of engines, the performance will never match, as they have a completely different purpose.
A diesel engine is designed to perform from a standstill, capable of moving heavy loads at lower RPM while using less fuel. This is beneficial when towing. Whereas petrol engines perform better at higher RPM and are capable of reaching higher speeds in a shorter time, they use more fuel.
Before considering performance upgrades, ensure your vehicle is mechanically sound and that any underlying faults are resolved by a qualified technician. In some cases, underlying performance issues are overlooked before modifications are carried out.
Understanding Performance Upgrade Options
If you require significantly more power without accepting the potential risks, upgrading to a vehicle designed for higher performance may be the better long-term option.
Modern vehicles are commonly modified through ECU remapping. This involves adjusting software parameters within the engine control unit to increase power output. While this can improve performance, it also increases stress on engine components and emissions systems. There is no guarantee that modifications will not reduce long-term reliability.
Remapping Technology
When a vehicle is remapped, the necessary adjustments can be made to the computer to improve performance, reducing the chance of engine damage. There is no guarantee that performance modifications will not reduce engine reliability. Unfortunately, some remapping services are carried out without proper vehicle assessment.
What If My Diesel Doesn’t Have a Computer?
Older diesel engines were often modified mechanically, increasing fuel delivery or turbo boost. While this could improve power, it frequently resulted in increased smoke, reduced fuel economy and shortened engine life.
Next was the transition into electronic diesel fuel pumps, where we found ‘plug and play’ performance enhancement devices installed. Eventually carried over to CRD, but we have witnessed this create more problems. The reliability of the wiring, for example. Vehicle manufacturers invest millions of dollars designing wiring systems to withstand heat, vibration and harsh operating conditions. Some plug-in performance devices can interfere with factory wiring and sensors, increasing the risk of reliability issues over time.
Emission Systems
If you decide to do any performance modifications, ensure your diesel is in fit working condition and avoid removing emission systems such as the Exhaust Gas Recirculation system (EGR) and Diesel Particulate Filters (DPF). These systems have been designed and engineered by the manufacturer, under strict guidance from the world’s emissions governing body, to reduce the harmful gases produced from diesel exhaust fumes. These deadly gases impact the environment, as well as our physical health and wellbeing. Removing emission systems is illegal in most jurisdictions and can result in significant fines.
On a final note, should you experience an issue on a modified vehicle, I strongly recommend that you return the computer to stock. This will ensure the correct diagnostics can be carried out by your mechanic.
Final Advice for Diesel Owners
Modern diesel engines are engineered as complete systems. Increasing power without understanding system limitations can reduce reliability, increase emissions issues and shorten engine life.
If you choose to modify your vehicle, ensure it is mechanically sound and the work is carried out by a qualified technician.
Diesel Help Australia works exclusively with professional workshops.
If you require diagnosis or repair, we can refer you to an independent workshop that is part of the Diesel Help technical support network.
Return to the Diesel Vehicle Owner’s Guide for more topics and maintenance information.
