Introduction

Diesel tuning boxes or ‘black boxes’, as they are sometimes known, have been around since the mid nineties when diesel engines started using computerised electronic control units (ECUs) to precisely control fuel delivery. Tuning boxes are an alternative to a vehicle ECU remap and consist of a small electronic box which is either hard-wired or plugged into the vehicle’s fuel system circuitry.

Mechanical Throttle Linkage

Typical Mechanical Linkage

A simple test that can be performed on most vehicles, to check if a black box is a possible option, is to check for the presence of an electronic throttle. By depressing the accelerator pedal with the ignition off, while at the same time observing the engine bay for any movement of linkages or cables connected to the throttle body, it is possible to determine if the throttle control is mechanical or electronic. As a general rule, if there is any throttle body movement, the throttle is cable controlled. If not, then it’s likely the throttle is electronically controlled and therefore a tuning box can be fitted in most cases.

How a Diesel Tuning Box Works
Electronic Throttle Body

An Electronic Throttle Body

Unlike an ECU re-map, tuning boxes normally increase the engine’s fuel quantity only and in most instances do not increase the engine’s turbo boost pressure. However, due to the way the diesel engine works, each combustion usually takes place in the presence of excess oxygen, meaning that, under most engine speed and load conditions, there’s oxygen available to burn any extra fuel that may be introduced.

Diesel is a very difficult and slow fuel to burn and that’s why diesel engines tend to smoke excessively under hard and fast driving conditions. Adding more diesel into the cylinders does indeed create more power but there comes a point where the extra power also produces extra smoke, especially at high loads and higher engine speeds.

First and Second Generation Tuning Boxes

Van Aaken Smartbox There are many different makes and brands of Tuning Boxes available to fit most vehicles. Some of the first generation types are analogue and simply use a resistor to alter ECU signal voltages. The more expensive second generation boxes are normally digital and some even claim to be fully mappable (which can’t be true unless it monitors engine speed, fuel quantity and engine load).

Gerd Van Aaken at CRD Performance

Gerd Van Aaken at CRD Performance

The Pioneer of one of the first tuning boxes is Gerd Van Aaken, previously of Van Aaken Developments, who is also the developer of the Smart Box, a second generation tuning box now marketed by Cybrand UK. Gerd’s expert advice and technical input has also been invaluable to us during development of our own third generation tuning box. Other popular brand names include The Original Tuning Box, Tunit, Chip Express, BHP Plus Speedhawk, DTUK CRD2 and CRD-T, Synergy, Spider, TDI Tuning, Racechip, TD Performance, to name but a few.

Tuning boxes are sometimes criticised because of how they work; most boxes fool the vehicle’s ECU into increasing diesel fuel rail pressure, with the exception of Steinbaur, whose tuning boxes electronically extend injector opening times, both allowing an increase in fuel quantity. These methods are not ideal since neither make adjustments in the same way a proper ECU re-map does, by taking reference from both engine speed and load.

At CRD Performance, Bolton, we can supply and fit any make and type of tuning box or, if a customer already has a tuning box, we’re more than happy to install that too. The cost of installation will largely depend on installation complexity and time, which in turn will depend on vehicle make, the type of tuning box, ease of installation and also whether or not a rolling road dyno setup is required.

Third Generation Tuning Box

Probably the most advanced third generation diesel tuning box available is The Select-A-Map; this common rail diesel control unit has been developed in-house, of which Eddie Zyla is the Technical Director and a major shareholder. The main difference between the Select-A-Map unit and previous generation tuning boxes is the way in which it controls the diesel by creating a 3D map, using engine speed and load, replicating a proper ECU re-map.

BMW 5 Series GT F07 530d - Select-A-Map Installation BMW 5 Series GT F07 530d
The Select-A-Map installed on a BMW 5 Series GT F07 330d, with its proud owner (right).

The vehicle pictured utilises the later N57 engine, which can also be found in the BMW 3 Series E90/E91/E92/E93 325d/330d/330xd, the BMW 5 Series F10/F11 530d, the BMW X5 E70 xDrive30d, the BMW X6 E71 xDrive30d, the BMW X3 F25 X3 xDrive30d, the BMW 7 Series F01 740d/740d xDrive, the BMW M550d xDrive and numerous other vehicles. For many vehicles such these, the Select-A-Map presents a good alternative to a remap, especially for vehicles where a remap is impractical or problematic.

Technical Information

For those of you who are technically minded and would like to know more about how the system works, click the link below to either view or download the full operater manual of the Diesel Control ECU.

Diesel Control ECU – Operator Manual

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View Manual Online
(Opens in a new window)
Download Manual
(PDF format – 1,950 KB)

Select-A-Map Retail Brochure
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View Brochure Online
(Opens in a new window)
Download Brochure
(PDF format – 1,562 KB)
Printer-friendly version
(PDF format – 923 KB)

There are many discussions on internet forums centred on what’s best; an ECU re-map or a diesel tuning box. As a supplier of both tuning boxes and ECU remaps, we have little to gain by arguing for or against either technology, preferring instead that the customer makes an informed decision that best suits his/her application and budget.

Customers are welcome to contact us to discuss the options available.

Price Guide

First generation tuning box (from) £85.00 +VAT

Second generation tuning box (from) £295.00 +VAT

Fitting cost between 1 & 2 hours (approx) £70.00 – £140.00 +VAT

Select-A-Map (from) £499.00 +VAT

Rolling Road Dyno Charge (from) £40.00 +VAT