Car Engine Tuning: General Information

Car engine tuning is the process of adjusting the settings of control programs for the purposes of changing the service of the controllers. It mainly refers to the correction of programs of the power control unit of a car including the changes connected with a number of characteristics and the use of some additional modules. Increasing the power of a car with the help of engine tuning isn’t dangerous. It doesn’t affect the mechanical engine units.

The history of engine tuning started starts in 1939 when the first engine supervisory module was introduced. The prototype of the electronic control module(ECM)  or electronic control unit (ECU) was the Kommandogerat system for the BMW aviation engine. German engineers tried to synchronize the throttle to influence the fuel combustion which improves the torque and increases its engine’s speed. This principle became the basis of the concept of «engine tuning«. Today, it is used to increase the speed and power of many cars unlocking and mobilizing the work of the engine.

Since 1994, a lot of electronics and different programmable systems have been actively used in the field of motor transport. The reconfiguration has gained its popularity and has become a popular service. Almost half of the engine tuning procedures were related to rewriting chips.

The modern tuning methods are very diverse. The re-flash is performed by connecting via the control units (internal or external) or the OBD2 port. In this case, the rewriting procedure is called remapping or ECU remap, because it isn’t connected with the chip.

The Aim of Engine Tuning

The main purpose of tuning is to increase the strength of the power unit. The procedure is conducted to reduce the fuel consumption, adjust ECU programs due to new changes in engine configuration, operations, and parameters of engine components. This may be done due to fuel switching, an air pump installment, replacement of the spray nozzles, etc.

Engine tuning is available for most cars after installing an autogas system. It is performed for correcting the software malfunctions made by automakers while entering the market without considering the specifics of vehicle operation in Russia. Many problems can be fixed with the help of engine tuning.

Disabling the Emissions Reduction Systems of the Engine

The emissions reduction systems of modern engines consist of several units that can be turned off using engine tuning:


  • The EGR system is designed to reduce the exhaust gas toxicity by partially returning it to the collector for reusing. Returning exhaust gases is very harmful to the engine, because they are saturated with small impurities that settle on the EGR, valves, collector and air duct. As a result, the cross-section of the tubes decreases due to carbon residue, the power of the power unit also declines, and the EGR system starts to malfunction. The EGR valve should be disabled to avoid entering the emergency mode. It will increase the reliability of operation, improves the durability and keeps the engine clean. Disabling this system leads to a great decrease in ecological attributes, problems with checking the ASU checking (for EU countries). Specialists can solve the this problem without connecting to the EGR system.
  • The second emissions reduction system is EVAP. It is used for capturing and afterburning the fuel vapors. This system is not reliable and is difficult to repair, since it is very hard to detect a failure in time. It leads to the failure of other expensive components. Disabling the system avoids such problems.
  • The SAP, is a system that supplies air to the catalyst for burning the exhaust gas. The system is activated only once the engine is turned on. If it fails, the only correct solution is to completely dismantle it. If not done, the engine’s power will decline, and the fuel consumption will increase.
  • The DPF is a maintenance-free carbon filter with several sensors. It is used to reduce soot and oxide emissions into the atmosphere. Due to soot residue it fails and needs to be replaced, otherwise the turbine is destroyed, the engine power declines, and the fuel consumption increases. However, you can get rid of the DPF completely by physically removing it from the system and disabling the corresponding settings in the car’s system.

All emissions reduction systems can be disabled by making some adjustments to the vehicle’s control unit. However, such manipulations should be performed by th1e specialists who have the appropriate knowledge and the necessary tools.

Disabling the EGR Valve

The EGR valve must be disabled with the help of engine tuning in two cases:

  • Failure of the valve itself at low mileage — when its software becomes useless. The power unit will operate in the emergency mode unless the EGR valve is disabled;
  • Car’s milage is more than a hundred thousand kilometers, and the system negatively affects the engine and doesn’t have a particular effect on the environment.

There are several ways of disabling the valve – via software (engine tuning) or physically. It is not enough to remove it, because the control unit will detect a failure and put the car in the emergency limited mode. Rewiring is the only appropriate way to disable the system by changing the control unit software. As a result, the emergency mode will not be activated when software problems are detected. An interference of an inexperienced mechanic will lead to various negative consequences or breakdowns. There are special software and tools that are used to do the work properly.

Disabling the Tank Ventilation EVAP

Evaporative Emission Control (EVAP) is the fuel vapor capture system that performs the function of tank ventilation. The system was used first when the EURO2 standards were accepted. Today, almost all cars have it. EVAP prevents the release of fuel vapors that appear in the fuel tank during evaporation into the atmosphere. The system provides their afterburning. It consists of a valve, a pipe, and an adsorber (activated carbon is used). The vapors accumulate in the adsorber, then they are periodically sent to the collector by the valve for combustion.

EVAP fails quite often. It is sometimes very difficult to find the cause of the failure. If the pressure in the tank increases due to a breakdown, the bypass valve installed in the plug opens. Disabling the system allows to avoid the most frequent problem — constant switching on the check engine lamp and the untimely detection of the other faults. These problems cost a lot to repair. The software shutdown allows for a simultaneous detection of other malfunctions and a replacement of parts of the system.

Disabling the Catalyst and the SAP System

SAP (secondary air pump) is a catalyst purge system designed to supply air. It acts as an element of the operations of the catalyst. Oxygen is supplied to the collector through the valves. Before entering the catalyst the exhaust gas passes through the collector, reacts with oxygen, and burns out. The remaining exhaust gas’s temperature increases, the gas is then sent to the catalyst. The increased temperature is sufficient for normal functioning of the catalyst. The SAP system only works for a few minutes after starting the engine and influences the efficiency of the exhaust system.

If problems appear, the SAP system should be dismantled. The failure is shown as an indicator on the dashboard. A decrease in powertrain power or an increase in fuel consumption can also be signs of a problem. Computer diagnostics can reveal many of such problems. The cause of failure is either moisture or carbon accumulated in the valve that leads to a system failure. The SAP can be disabled using software to avoid expensive repair costs.

Disabling the DPF

DPF is a diesel particulate filter. It is installed on diesel engines and is a part of the car’s exhaust system. This filter is equipped with several sensors:

  • An oxygen sensor;
  • A differential pressure sensor;
  • A temperature sensor.

A closed filter cannot be cleaned if it is more than half dirty. It is used to reduce the emissions of oxides and soot that appear when the fuel is not fully burned. It reduces the soot emissions almost completely. It consists of a tube with a ceramic matrix in the form of a grid with the cell diameter of 1 mm. The small particles of the exhaust gas are retained by the porous structure. The filter is located behind the catalyst, and is sometimes combined with it and placed behind the exhaust manifold. The operation period is about 70-100 thousand kilometers of milage. It depends on the operation conditions.

Soot accumulates in the filter and prevents the exhaust gases from escaping. As a result, the power of the power unit is reduced. A replacement is then needed. Appropriate adjustments can be made in the ECU.

If  the filter isn’t removed or replaced, the following problems will need to be solved:

  • The fuel consumption increases, and the engine power decreases;
  • The EGR valve fails;
  • The oil properties are violated;
  • The turbine is destroyed.

After the filter is physically removed, the emergency mode is activated. Software adjustments should be made, and the monitoring sensor should be disabled.

Disabling the SL Using Software

SL is a speed limiter, which is used to control the speed at a certain limit level. It controls the fuel supply using the injection control unit and sends the information to other units determining the speed limit. The SL is installed by the manufacturer on all cars including trucks. It provides a comfortable level of driving in the city and saves fuel. In general, disabling is used to remove any restrictions. SL sometimes causes difficulties during driving, especially if the car is heavily loaded or while traveling through the hills. The system can only be disabled programmatically with the help of special hardware.

Increasing the Engine Power

Engine tuning allows you to increase the power of the power unit by 5-20%. During the adjustment process, the values of the control signals transmitted to the car devices with the help of the chip are changed. Any other parts of the car are not affected. All the changes are made using software. It is impossible to do engine tuning on carburetor models; it is available only on injector models.

Engine tuning gives the following results:

  • An improve of vehicle handling and vehicle dynamics;
  • An increase in engine power;
  • Reduced fuel consumption while using the proven software.

Some firmware reduces fuel consumption, but leads to a loss of dynamism of the car. During the summer, engine’s sensitivity to high temperatures increases, the life of the power unit decreases due to the insensitivity to the quality of fuel. It leads to detonation and of different components. The amount of harmful substances in the exhaust gas also increases.

Ignition Dwell Angle

Ignition dwell angle is the angle at which the crankshaft turns when the spark plug is powered until the piston reaches its highest point. In the moment of ignition advancement, the mixture ignites for the piston to occupy its highest point. The moment of ignition has a great influence on functioning of the power unit. If ignition occurs too early, the gas pressure counteracts the movement of the pistons. As a result, the engine power declines. The engine may overheat. The ignition advance is characterized by the ignition dwell angle. The optimal value depends on the ratio of the number of turns of the motor and fuel’s rate of combustion. In modern injectors, the ignition dwell angle is determined by ECU. It includes the indications of software and sensors, so there is no need to install any centrifugal regulators.

Raising the Torque

Torque is time spent by the power unit accelerating to the maximum speed. There are two ways of changing this value and a combination of them which is considered to be the best option. In the first case, the engine elements are optimized or completely replaced with the analogs that have higher capacity. Power gain can be up to 30%. Engine tuning is suitable for the injection vehicles. It uses a modified chip that sends the signals to the main units of the car. In other cases, the cylinder head, camshaft, combustion chamber, and pistons are modified, and the engine’s displacement is greatly increased.


Reducing the Fuel Consumption

There are many ways to save fuel – reducing loads, mechanical changes, changing one’s driving style. The type of transmission also affects the fuel consumption. In automatic models, the engine uses one liter more, but an optimal type of driving reduces this amount to zero. Fuel expenses can be reduced using engine tuning. It is considered to be one of the most effective and simple ways to do so. In the process of software adjustment, the power unit capacity increases, and the fuel consumption decreases. This procedure is especially relevant for models with a small engine volume. During tuning, the program parameters responsible for the operation of the engine are changed. The ECU is reprogrammed so that the injection and air quantity would be optimally combined. Air pressure, engine speed, and ambient temperature directly affect the injection parameters.

The Autogas System

The autogas system is a complex propane-butane fuel supply system. It consists of electronic and mechanical units and is connected to the ECU. Autogas allows you to reduce by several times the fuel consumption. The engine runs more gently, the mixture has a high octane number and completely burns out. The engine works longer, fewer harmful substances are released. The latest generation of systems corresponds to the European ecological standards Two types of fuels may be used using manual or automatic switching. There are several generations of such equipment, and they differ by the principle of gas supply. The models of the 1st and the 3rd generations are outdated and cannot be installed in new cars. The 4th  generation is suitable for almost all injection models. Generation 5 and 6 are rarely used. The car consumes less fuel, but the power of the power unit remains the same. The systems are suitable for all modern cars.

How Is Engine Tuning Performed?

The processes that are performed while flashing the standard ECU program include three steps:

  • In the absence of the original firmware, the standard program of the onboard computer is read.
  • The diagnostics of the original firmware is performed. If it is not installed, the original program is edited, and the processes are improved and refined. After that, all the software malfunctions are detected.
  • The tested and diagnosed program is installed on the controller.


Before that it is necessary to check the car for any other faults. For example, the loss of power  may not be connected with the firmware, but with the breakdown in the engine or some parts of it. In this case, tuning will be a simple waste of money. Used cars should be rechecked on having been chipped earlier. After that, the factory program installed is read, and a backup is made to rollback in case of a future failure. Then adjustments are made. This process should be conducted only by professionals.

Vehicle’s capabilities are considered during this operation. Programs and cars are individual – it is important to remember that. Installing updated firmware on the controller takes several hours to complete. This process should be performed while the ignition is turned on to avoid any problems. At the last stage, the vehicle systems are verified for compatibility with the new firmware. In the end, the car’s capability is checked while driving or at the stand to confirm that tuning is finished, or it still has to be improved.

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