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Custom ECU Tuning files


For any formally qualified automotive/calibration engineer the reality of ‘custom remap’ debate is ignorant and frustrating for a number of reasons;


Firstly – . After 2004 most engine management systems became a closed looped torque based model simply put, the engine management is adapting (optimizing) the tune of the engine in almost real time based on the hard code or what is known as the statistical dynamics element of the memory. A quality remapping engineer understands and respects this and simply enters the correct desired targets in the correct places to the code and the system references the sensors accordingly (closed loop or PID) thus using these settings to achieve the desired result. The one and only time a ‘custom’ strategy is required is when a vehicle is modified to a point where the dynamics employed by the factory ECU are no longer valid for example – a larger turbo is fitted requiring new PID loops to be employed.

Modern torque based engine management systems are way beyond in technology and calibration terms to some guy mapping fuel and boost tables on a dyno cooling with a carpet blower. An engine is a air pump driven by the heating of air from a relative dew point to a maximum permissible EGT. More expansion = more power.

Think of an ECU in its simplest form, it’s a calculator programmed to receive values in terms of voltages and frequencies at a rate of 1 to 200 HZ or in layman’s terms 1 to 200 times a second dependent on the type of value it needs to sample. For example – sensor values such as coolant temperature, are a slow changing value, so a sample of 1-5 HZ is fine. Where fast changing variable’s such as manifold pressure, It requires a faster sample rate of say 50 HZ or 50 times a second. The processor then first of all references (for the sake of this explanation) three memory models within the ECU, one known as ‘statistical elements’ and the others as we know them as ‘maps’ and ‘curves’

Statistical elements

This is the core structure of the ECU function – It can be made up by a number of control algorithms such as ‘Motronic’ and elemental rules such as ideal gas law, this also includes configuration switches and curve/map address library for the controller to switch between based on the strategy or mode required.


The curve structures in the ECU are a vital and are often mistaken as torque limiters by ‘CUSTOM MAPPERS’ or re-scaled in a effort to bypass a mechanical limit resulting in a loss of resolution and refinement. An ECU can only interpret what a engine is doing by its input signals via the relevant sensors. This is usually done by voltage or frequency – so the ‘curve’ is the real world signal conversion to a digital value the ECU can use in a calculation to out put to its PWM’s


Basically a data matrix, a table of data values arbitrated to a output of the ecu drivers or PWM’s referencing values such as requested torque, boost, lambda and air flow. These are desired targets based on the data and control logic influenced by the ‘curve’ and ‘statistical elements’. ALL employing PID control – understanding this will expose the ignorance of most chip tuners time and time again we see duration loaded calibrations with no adjustment of lambda, just one of many contradictions suffered.

A correctly calibrated ECU will ‘custom tune’ an engine down to the millisecond – the clue is in the name ‘Engine Management’ 

Smoke will damage a modern Diesel engine

Automotive manufacturers go to huge lengths to achieve the perfect/maximum thermal efficiency in engine design striking the perfect balance from a induction temperature and the heating point of the fuel vs permissible exhaust temperature (EGT) whist targeting the idea push/pumping(expansion) cycle or adiabatic process. Extracting more performance from a diesel engine for a manufacture is purely down to controlling EGT relative to particle and Nox (nitrogen oxide) emissions the very reason implementing the use of DPF systems.


So how is the damage done? – By modifying the lambda (fuel relative to air) the first issue is the over loading of the DPF management cycle as the filter is designed to handle a certain amount of matter vs measured flow vs a oil quality / engine ageing strategy, think of it like this – tuning a engine it is a given performance air filters provide more airflow by using better more expensive materials. Currently there is no material solution for DPF to achieve performance increase other than (at best) an increase regeneration cycles to keep flow optimized resulting in increased fuel use for such a regeneration leading to the inevitable shorted life cycle. So adding fuel = Dead DPF.

pcw-turboTurbochargers suffer greatly from tuning ignorance, and are a fundamental component in managing the efficiency of a engine. The compressor map of a turbo dictates the dynamics of the air heating process with the cylinder temperatures vs EGT calibrated precisely known as the ‘flame wall’ as diesel fuel ignition timing is dictated by the mass vs relative fuel temperature respecting thermodynamic variables / eg – the fuel pressure (endothermic reaction), fuel mass (duration), start of injection (timing). We see issues with calibrations where the mass (duration) is modified the SOI (timing) is modified along with increased rail pressure resulting in the movement in flame wall causing a cascade rise in EGT thus damaging the turbocharger due to the pardox of increased boost pressure only compounding the issue. Another issue born out of over fueling and flame de-tuning is the sooting of the exhaust wheel of the turbo causing a imbalance of the turbine and jamming of a variable geometry where applicable thus greatly reducing the life of the turbocharger.

Drive line and chassis harmonics – Manufacturers again go to huge length to control engine running frequency and this ‘noise’ causes long term damage to components a simple example is the presence of a dual mass flywheel which is tasked in part to countering this issue in conjunction with tuned engine mounts and phased injection strategies. By not respecting these components in a calibration all will lead to early failure.

The work is already done in the ECU to increase the performance to a sensible point without compromising the powertrain the key is understanding the physics on which the calibration was designed, so the next time you see a youtube video of a vehicle pumping a dyno cell full of black smoke think about what you have read here and the ignorance of some tuners.


Let’s take a look at the CMD OBD flash tool. The tool at first glance is what would be classed as an all in one tool. Apart from being solely an OBD flash tool it can also be upgraded to support a number of boot loader protocols. On this occasion we will be just looking at the OBD part.

protectionSo, to make it simple lets break it down in to different parts, let’s first look at the GUI and software.
The first thing you will notice with CMD is that the tool is secure, in the fact that the software and the tool have a security protocol. The tool must go online and handshake the CMD server at set points in time. This ensures total tool security against cloning and also from theft.cmd

After pairing the tool to the PC we can now start the software and have a look at the layout and protocols offered. From the first glance the software looks very basic in terms of a fancy GUI, as unlike its competitor all the vehicles are not laid out with make, model, engine size, output etc. The CMD is a tool for people who are already at an advanced stage of chip tuning, where they don’t need a babysitter and should already know the differences between vehicle models and ECU specs.

The CMD has another major feature under its belt, a VIRTUAL READ function. This feature lets you download original files from CMD’s online server 24hrs a day for ECU’s that cannot be ready by OBD alone. This includes boot loader only reads such as ME7, ME9, MEDC17, Simos, Visteon DCU102 and the once popular EDC16 Opel ECU. This was a major breakthrough for Opel vehicles, where tuning, EGR and DPF modification could only be done by BDM method. The CMD can virtual read the full BDM file then write the full modified file back through the OBD port, thus saving time and removal of the ECU.

Read speeds with the CMD are undoubtedly the fastest out of any of the tools. Virtual reads are circa 30 seconds; with OBD reads with vehicles on CAN usually range from 2 minutes to 20 minutes. This is a major positive for busy shops or mobile users.

Flashtec are also at the forefront of new protocols and read/write techniques. They release a steady stream of very usable updates, usually first out of the tool manufacturers, which work first time.

The tool has industry standard features such as a battery real time monitor, a recovery function in case of interrupted flashing, DTC clearing function, automatic checksum correction for all protocols, Automatic resistor switch-KLine 470 ohm pull-up resistor for VAG EDC16.

Overall the CMD is a very stable tool, Very reliable and gives you piece of mind when you press read or write button that the tool will perform.

As with everything, one tool cannot be good at everything. The only downsides that can possibly be found to the tool are that of the older / unpopular protocols i.e. older ford/jaguar vehicles and some Japanese petrol vehicles, but on the flip side it can flash all the newer models.protocols

Also with the CMD the online protocol / virtual read functions can be problematic / slow / not work if you are not in a wifi or 3g/4g data area.

Unlike its competitor, the CMD does not come with the free ST boot-loader function but in comparison it is not really required as the virtual read will give you the required file. The boot-loader is only required to read out already modified files.


I would score the CMD a 9/10.

Positives would be unrivalled read and write speeds, the virtual read function, its security and also the upgradability of the tool – so a 2nd tool does not have to be purchased.

Negatives would be that a few of the older vehicle protocols are not covered and the tool can sometimes be a problem without an internet connection.

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