Tuning

Tuning


I have decided to tune my car. Well, that’s not entirely true. When I bought the GTI, part of the reason was its ‘tune-ability’, and the access to a variety of high-quality aftermarket modifications. So essence I have committed to researching tuning options, with a date in mind for the tune. January 2024, the end of the warranty.


Tuning at the end of the warranty was important to me as have never had a car under warranty; I’ve always bought used. The GTI was used, however, the previous owner had taken out an extended warranty, giving me an extra 3 years of coverage. 


Before I get into the article and explore the different tuning options, let us be unequivocal, tuning of any description will void a car's engine warranty. And, indeed, if something went wrong with say the differential or gearbox a car company could make a compelling case that the tune was the culprit. Indeed I’m fairly sure dealerships could construct a compelling argument that any modification is the cause for a raft of mechanical defects and failures. 


I started some preliminary research on tunes, basically reading about the ubiquitous APR and COBB versions. Realising there are many different methods to go about tuning a car, thousands of different brands and an equal amount of variation on how these providers achieve their results, I decided to write this article. 


Please note I am a car enthusiast, not an expert, mechanic, engineer or computer boffen. Below is a synthesis of the research I have collected. Realising there is so much information, fact, and fiction, littered with opinions, I thought it might be helpful to collect and place this information in one spot. I have aimed to verify all information from multiple sources. This is as much a depository of information as it is a record of my tuning journey. I hope it helps.  Some elements of tuning remain a ‘wait and see’ game, so if there is no definitive information on the tune's overall effect on a car, I have suggested things one must consider.


What is a tune?


In this article, we are talking about altering the way the electronic control unit (ECU) manages all aspects of the car's internal workings. Tunes do this in a variety of ways, which I will explore later, but for now broadly speaking we are talking about changes to spark, timing and air-to-fuel ratios. In forced induction engines this can also include an increase in boost pressure to improve performance.


The variables controlled by a computer that affect a car's operation and performance have increased markedly in recent years. Computer modules now offer adjustability to gearboxes, suspension and exhausts to name a few. Additionally, this increase provides manufacturers more opportunity to affect emissions, reliability and longevity. However, here I will focus solely on tunes that affect engine management systems. 


So why get a tune?


The primary reason to get a tune is to improve the overall performance of your vehicle. By improved performance essentially we are talking about more power, more torque, and therefore improved acceleration. The tune will achieve this. However, the performance of a car also includes handling, grip and general drivability. 


The tune will affect these in various ways depending on the setup. Therefore it is highly probable, that once you complete a tune, further modifications to brakes, suspension and exhaust, to name a few, may be required, or at least worth consideration. In the case of forced induction, more power will likely increase heat, the enemy of turbochargers. Therefore a larger intercooler may need consideration to ensure reliability, and the ability to take full advantage of the tune. The slippery slope of car enhancement!


What are the risks with a tune?


Firstly as previously stated, once you get a tune, the engine warranty is voided. More than likely if something does go wrong with the car, the manufacturer will be able to build a compelling case that the tune caused the fault. So in essence a tune equals no more warranty. Some tuners now offer warranties, such as APR. These are limited powertrain warranties that cover what is left on the original warranty. Whilst providing piece of mind post-tune, ensure you examine the specifics of any such warranty’s coverage.


All manufacturers develop cars based on a compromise of competing variables, power, efficiency, reliability and longevity. When a car such as the Golf GTI is set up from the factory, the demands placed on the engine, turbo and other components are conservatively set within parameters that ensure reliability and longevity. 


There is room to move within this band, without over stressing an engine, knowing what the safe limits are is the key to a successful tune. What these safe limits are is dependent on the opinion of the tuner/tuning house, and the research they have completed, or not completed on their product.


Car manufacturers spend years and millions of dollars developing a car prior to its release. This includes stress testing the engine components to ensure they are fit for purpose, particularly more rigorous when it comes to performance models. The question you need to ask yourself is - has the tuner, or tuning developer done likewise?


If the tune doesn’t cause damage to the car, it is likely to increase wear and tear on renewable items such as brakes, fluids and tyres to name a few. Therefore, at the very least expect increased maintenance costs, and perhaps more frequent servicing. A conservative tune, done correctly within what the car's internal structures can safely manage won’t necessarily cause damage, and correct, regular maintenance should mitigate any degradation over time.


Don’t forget every time you drive the car, this constitutes wear and tear. Each time you go for a spirited drive through the hills or a track day. This degrades the car's consumables and stresses the engine. Cars are made to be driven. Many manufacturers leave room for safe tuning. Therefore tuning doesn’t have to be something approached with trepidation, more a decision of what you want to achieve, balanced with the risks and ongoing maintenance costs.


Speaking of maintenance, be aware dealers can detect a tune, and many may refuse to service your vehicle. Further to this, check that your insurer covers a tuned vehicle. Many insurers allow for certain, or a limited number of modifications. However, be sure to specifically check where they stand in regard to tuning.


Types of Tunes


There are three main approaches to tuning a modern car; 1) Piggyback Tuning, 2) ECU Tuning, and 3) New Custom ECU.


Let's look at the third option first. Essentially this means replacing your car’s factory ECU with a new, aftermarket ECU from the likes of Haltech. New ECUs are extremely costly and would need to be installed and mapped by experienced technicians on a dyno. This option does provide a more comprehensive approach to tuning your car's engine parameters. However, modern cars will have advanced ECUs willing to accept tunes on an extensive list of parameters. This option is generally taken in high-end builds where a number of modifications have been made to the car.


Piggyback Tuning:


Many cars ’ ECUs will adjust parameters such as boost and ignition constantly during driving to suit the conditions and driving style. That is to say, car manufacturers will set power and torque targets that the car must meet at certain rev ranges, temperatures and selected gears, to name a few. Essentially boost, and other parameters are variable depending on these conditions. What a piggyback tune does interrupt the signal from engine sensors before it gets to the stock ECU. It tricks the ECU into thinking the aforementioned targets haven’t been met. For example, telling the ECU that the car is running lean, consequently adding fuel, and thus increasing power.


Advantages:



Disadvantages:



ECU Tuning / Remapping


As the name suggests ECU remapping involves altering the factory settings across parameters such as throttle position, fuel duration, boost pressure, torque and boost limiters to name some. 


There are two methods to take when tuning a car with this method. The first involves purchasing an off-the-shelf tune for your car from companies such as APR, COBB and REVO. These have distinct similarities and differences that I will attempt to cover later. Some of these can be purchased and installed by yourself, and some, as is the case with APR, can only be purchased and installed by licensed dealers. 


The second method is taking your car to a tuner, who will use a dyno to establish a baseline for your car across the aforementioned parameters, and then alter these according to your requirements, and hopefully within the limitations of the car.


Advantages of off-the-shelf tunes:



Disadvantages of off-the-shelf tunes:



Advantages of custom tune:



Disadvantages of custom tunes:



Next up, a review of the various products falling into the aforementioned areas.