This past week, a colleague at work asked me my opinion on ECU remapping. Of course, the knee-jerk response of the engineer in me would be an immediate “No, Don’t do it”.

However, I realised he had already modified his engine and was asking as an afterthought. In much the same way that my wife knows that when I begin a sentence “Babe, would you be mad if I bought a…”, it actually means that I have already bought the item, and hidden it in my garage, and I want to know if it is safe to bring inside. As such, I advised him on the best way forward, and other vehicle components which need to be upgraded corresponding to his increase in power.

Let us have a look at some of the popular ways to enhance the performance of an engine, and the potential drawbacks.

Tuning Chips

Tuning chips were designed for diesel engines and claim to boost both engine performance and fuel economy. While most drivers notice an increase in performance, few notice an improvement in fuel consumption. In reality, many drivers who have installed them find that they make their engine smoke, which is why they often referred to as “Smoke boxes”.

How does a tuning chip work?

The tuning chip we are talking about here is not a chip in the way you are thinking. They are resistors. Tuning chips are not ECU chips (microprocessors within your car’s main computer that control engine and transmission operation). The resistor in question has only job – it changes the air temperature sensor’s readings that are sent to the computer.

The vehicle computer uses temperature and density information to determine the amount of fuel to send to the engine. Tuning chips deceive the computer into thinking that it is receiving colder, denser air than it really is. Cold, dense air has more oxygen than warm air, which means that you get better combustion. The computer compensates for this by sending more fuel to the engine, resulting in more “bang.” This basically boosts performance.

Why tuning chips can damage your car?

While fooling your cars computer may seem like a great idea at the time, owners and mechanics often report the following problems:

• Inaccurate fuel mileage information
• Smoking from the exhaust
• Reduced fuel economy
• Damage to the engine’s pistons
• Increased emissions
• Rough idling

If you are determined to increase your car’s performance, the best option is to go with a re-mapped ECU that allows you to adjust both the engine’s performance and your car’s computer. However, ECU remapping has its drawbacks too.

ECU Remapping

Fiddling with the systems in your car’s Electronic Control Unit (ECU) used to be known as ‘chipping’, because you literally had to swap out a factory microchip for a new one programmed by your supplier of choice. As remapping technology has advanced, the techniques have changed too. The geekiest enthusiasts these days write their own ECU programmes on readily available laptop software and upload them via the car’s Onboard Diagnostic Port (OBD). 

Remapping, sometimes called ECU tuning, is when the settings of a car’s ‘engine control unit’ (ECU) are altered to improve several areas of the vehicle’s performance. By overwriting the existing settings with new software, the owner can re-programme the car to manage the fuel injection, airflow, sensors and more.

How does ECU remapping work?

Remapping a car changes the manufacturer’s default settings and software on the ECU, replacing it with new software which can be tweaked and customised to the owner’s specifications.

In simple terms, there is a program stored in your car’s computer module, which is basically a lookup table. This table is set by the manufacturer and contains information that ‘tells’ your engine how to behave under certain circumstances.

For example, if you are driving on the highway at 100 kilometres per hour, and you quickly accelerate, your car’s computer detects this and asks the chip what to do in this situation.

Your car’s chip examines the lookup table and tells the car’s computer how much fuel should be sent to the engine, when to shift the gears for automatic cars, how to change the timing, and many more. The factory chip has all these parameters in the lookup table.

Remapping an ECU, means changing the values and parameters in this lookup table. Remapping an ECU is effectively overwriting the old ECU software.

Why can ECU remapping damage your car?

By adding power, you are increasing the pressure and heat within the cylinders. This in turn adds stress and reduces your engines life. Unfortunately, there is not a way around this. If you are keen on boosting your car, you need to ensure the internal components can handle the added stress. For this reason, forged pistons, rods, and cranks are some of the most widespread aftermarket parts. 

There is a reason that a motor manufacturer decides to set the parameters that it does on an engine. Usually, manufacturers try find the best compromise between engine performance, fuel economy and emissions, and power train durability. It is a delicate balance. The minute you tweak the engine for one of these criteria, the other two are likely to be negatively affected.

Stage Tuning & Component Upgrades

There are different stages of tuning, known as “stage tuning”. Stage 1 tends to be a series of modifications that can be fitted on their own to a standard car. This would include remaps that do not require any additional hardware, intake and exhaust upgrades. Stage 2 can be a little different between cars, depending on what their weak spots from the factory are, but the common theme tends to be removing limiting bits of the exhaust in combination with software that takes advantage of this. At Stage 3, you push the engine t past what it was originally designed to do, various components that were quite happily doing their job at a lower power level will start to need replacing with higher rated parts. By the time you have reached this point many of the following components will probably have been added or upgraded:

• Air Intake / Air Induction System
• Exhaust
• Intercooler
• Engine & Gearbox Mounts
• Fuel Injectors
• Fuel Pump
• Turbocharger

What Else Should I Upgrade?

In addition to what is listed above, there are several other components that you could also consider, including: (This is what I advised the guy at work)

Brakes

While not always mentioned on lists of required hardware, if you’re accelerating and driving faster, it only makes sense that you should be able to slow down or stop sooner, which means upgraded brakes. In real world driving on many roads, you are probably going to find yourself varying your speed a lot in response to road conditions. Being able to wind on more speed on a clear straight is going to result in you working your brakes harder as you slow down again for corners and the like.

Tyres

Tyres play a huge part in how your car goes, stops, and corners. If you do not want to waste the extra torque your engine now has by spinning up your tyres all the time, making sure you are fitting good grippy tyres will certainly help matters. They also help you slow down again, which is equally important. With more torque on offer, you are going to want more grip from your tyres

Clutch

This one does not necessarily get mentioned as being required hardware, but it is worth thinking about when considering higher stages. The big torque increases on offer on some engines can overwhelm your original clutch. At some point, investing in a performance clutch may prove worthwhile.

Suspension

As with tyres, anything that lets the extra power go to waste is the enemy here. The upgraded suspension will help keep your tyres in firmer contact with the road surface during acceleration or braking. You are also going to be able to go faster with more power on offer, so having a car that handles well at speed is definitely a good idea.

Oil & Maintenance

While maintenance is always important on an engine, it is especially important once you start tuning it. I would recommend following the service schedule closely and using high quality fluids that meet all manufacturer recommendations. Oil is especially important, as it is the lifeblood of your engine.