# Stage 3 ECU remapping

> Stage 3: software for engines with an upgraded turbo, injectors or internals. How we coordinate the project with whoever fits the parts and the data we need.

- URL: https://www.reprogramacionesmbv.com/en/ecu-remapping/stage-3/
- Index for AI (llms.txt): https://www.reprogramacionesmbv.com/en/llms.txt
- Versión en español: https://www.reprogramacionesmbv.com/reprogramacion/stage-3/
- Reviewed: 2026-10-15

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A Stage 3 is a project, not a file. There are parts to fit, a goal that has to be defined in writing and software that's refined over several rounds. Here's how we organise it and what we need from each party.

**In short:** A Stage 3 is the remap of an engine that has had its power-limiting components replaced: a larger turbo, higher-flow injectors or high-pressure pump and, often, strengthened pistons, conrods or cooling. There's no starting file: the software is developed for that specific combination and refined in stages using logs of engine parameters with the engine running. We can also do the mechanical work ourselves, or coordinate with your tuner based on their technical data; dyno tests, when needed, are carried out at partner workshops. It almost always requires processing a vehicle modification, and many projects end up being track-only. Price on request depending on the project, in the Community of Madrid (the Madrid region).

## What a Stage 3 is

There comes a point where software can't extract any more without some part working beyond its margin: the turbo can't supply more air, the injectors can't deliver more fuel or the engine can't take more cylinder pressure. A Stage 3 is what comes **after replacing those parts**. The most common ones are:

- **A larger turbo** or a modified stock turbo: more airflow, at the cost of slightly slower response low down.
- **Higher-flow injectors and high-pressure pump**, to be able to burn that air.
- **Strengthened internals** (pistons, conrods, gaskets) when cylinder pressure demands it.
- **Cooling**: radiator, intercooler and sometimes oil cooling.
- **Clutch, gearbox or differential** to match the torque being targeted.

Unlike [Stage 2](https://www.reprogramacionesmbv.com/en/ecu-remapping/stage-2/), here the software isn't adapting the stock map to parts that breathe better: a good part of the tables has to be rebuilt, because injection quantities, boost pressure and sensor scaling bear no resemblance to the factory ones.

## How we run a project

1. **Goal in writing**: what the car will be used for (road with a legalised modification, track days, motorsport), what kind of delivery you want and what the budget is. Everything else is decided from here.
2. **Component sheet**: the technical data for what's being fitted (we have it if we do the fitting; if not, your tuner sends it to us): turbo, injector flow, pump, range of the pressure and temperature sensors, compression ratio if it's changed.
3. **Reading and copying the original**: we save the complete factory software before touching anything.
4. **Cautious first version**: a file that starts and runs the engine with generous margins, to check everything responds as expected.
5. **Logging and refinement in stages**: with the engine running under safe conditions we log requested and actual boost, mixture, exhaust gas temperature, and ignition or injection corrections. Each round brings the file closer to the goal.
6. **Final version and documentation**: we give you a summary of what's been adjusted. If it needs measuring on a dyno, we do that at a partner workshop.

### Who does what

| Part of the project | If we do everything | If you have your own tuner |
|---|---|---|
| Choosing and fitting the turbo, injectors and internals | We fit them at the workshop | They fit them; we give our view on how they fit with the software |
| Technical data for the components | We have it from the fitting | They send it to us before we start |
| Mechanical condition, leaks and cooling | We check it | They check it; we see it in the logs |
| Software development | Us | Us |
| Dyno | At a partner workshop | At a partner workshop or wherever they work |
| Processing the vehicle modification | Our workshop certificate, technical service report and ITV | We explain what changes in the ECU |

If the tuner already works with their own reading tool, it can be organised as a [file service](https://www.reprogramacionesmbv.com/en/trade/file-service/) with several deliveries.

## What has to be sorted beforehand

A Stage 3 magnifies any weak point. Before starting on the software, these have to be settled:

- **Cooling**: the engine is going to produce more heat. If it already runs hot under hard use, that has to be fixed first.
- **Fuel supply**: the low-pressure pump has to hold pressure at full load.
- **Clutch and gearbox**: rated for the planned torque, not the stock figure.
- **Brakes, tyres and suspension**: they're not software, but they're half of the project's safety.
- **Sensors**: if boost pressure is going to exceed what the stock sensor can measure, a wider-range one has to be fitted; without it the ECU is working blind.

## Track use and road use

A Stage 3 changes engine components and power output, so on a car driven on public roads it's a **vehicle modification (reforma) that must be legalised** under Real Decreto 866/2010 (Spain's regulation on vehicle modifications), with a technical service report, a workshop certificate (we issue it) and an inspection at the ITV. Driving with an unauthorised significant modification is not allowed (art. 12.7 of RDL 6/2015, Spain's Road Traffic Act). In practice, the deeper the change, the harder it is to legalise, and many projects are planned for the track from the outset.

Our recommendation is to decide on the use **before** buying parts, not afterwards. The detail is on [legality, ITV and insurance](https://www.reprogramacionesmbv.com/en/legality-itv-insurance/).

## Price

It's **price on request**: it depends on the engine, the components, the number of refinement rounds and whether the transmission control unit is also involved. With the component sheet and the goal, we give you a quote per project. Our remaps start from from €200 + VAT (€242 including VAT), but a Stage 3 is nothing like an off-the-shelf remap.

Tell us the car, what it will be used for and which components you plan to fit (or have already fitted). We'll tell you what data we need and how we'd organise it.

## Frequently asked questions

### Can you just give me the file now and we'll fine-tune it as we go?

That's not how we work. A file made before knowing which turbo, injectors and sensors the engine has is a gamble. First we need the component sheet; with it we prepare a cautious first version and from there it's refined using real logs.

### Who fits the turbo and the other parts?

We can fit them: we also do the mechanical side of a Stage 3. If you already have a tuner, we coordinate with them and tell them what data and logs we need. If you're a garage and want to work like this regularly, see [garages](https://www.reprogramacionesmbv.com/en/trade/garages/).

### Can a Stage 3 be legalised?

In some cases yes, by processing the vehicle modification with a technical service report, our workshop certificate and an inspection at the ITV (Spain's compulsory periodic vehicle inspection, similar to the UK MOT), but with changes this deep it's a long process and not always possible. That's why many projects are planned from the outset for motorsport. Before buying parts, find out about the process: there's a summary on [legality, ITV and insurance](https://www.reprogramacionesmbv.com/en/legality-itv-insurance/).

### What about the gearbox?

It's one of the first limits to appear. On manuals, an uprated clutch is usually needed; on automatics and DSGs you have to see whether the gearbox can take the torque and, where possible, adapt its control unit. We cover it on [automatic gearboxes](https://www.reprogramacionesmbv.com/en/automatic-gearbox-tuning/).

### Do you keep the catalytic converter and particulate filter on a Stage 3?

On a vehicle driven on public roads, yes: the project has to take them into account. If the car is for motorsport only, that's a different conversation, and we have it before starting, as we explain on [deletes](https://www.reprogramacionesmbv.com/en/deletes/).

## Sources

- [Royal Decree 866/2010 on the processing of vehicle modifications (BOE, Spain's official gazette)](https://www.boe.es/buscar/act.php?id=BOE-A-2010-11154)
- [Royal Legislative Decree 6/2015, Spanish Road Traffic and Road Safety Act, art. 12.7 (BOE, Spain's official gazette)](https://www.boe.es/buscar/act.php?id=BOE-A-2015-11722)