To increase the performance of an engine, modifying the engine management system (often referred to a ‘chipping’) is usually considered. If the mechanical specification of the engine is changed the management system must be recalibrated to suit the new specification.

With a turbocharged engine it is relatively simple to increase the horsepower by raising the boost pressure. However, this must be done within sensible limits, and with the relevant changes to the fuel and ignition timing settings otherwise serious engine damage could result. To help to prevent engine damage, the standard management system contains a pre set boost limit, should the boost reach this limit, the management system stops the fuel injectors (making the engine cut out) until the pressure drops to what is considered a safe level.

There are a number of ways of raising the boost pressure, and as not everyone has the ability to modify the original management systems this can dictate how the work is done.

The simplest method is to fit an electronic device into the wiring that alters the boost pressure signal to the management system. This will ensure that the signal never reaches the pre-determined safety cut out level. Then, using a crude bleed valve fitted to the boost control pipework, the boost pressure is raised.

We do not like to increase a Subaru engines power in this way for a number of reasons. We don’t believe that it is good to ‘fool’ the engine management system buy altering sensor readings. The management system relies on the information from all of its main sensors to accurately calculate fuel, ignition and boost control settings. Although they are very clever pieces of equipment, any computer fed inaccurate data can only give out similarly inaccurate information, this can easily lead to severe engine damage! Another potential problem with this method is the crude methods used to raise the boost pressure. The standard system operates what is known as ‘closed-loop’ control of things like the boost pressure. This means that the management is constantly monitoring the boost pressure, comparing this to predetermined levels, and adjusting it (up or down) accordingly. The bleed valve will override that system, which can severely affect throttle response. Also, as the management system is not aware of the true boost levels, they could easily be increased to a dangerous level.

The management systems fitted to the Subaru models can (so far) be split into five main categories:
1.Pre 1997 model year,
2.1997 – 1999.
3.1999 – 2002.
4.2002 – 2004.
5.2004 onwards.
As the management systems have progressed, they have increased in complexity and ability. The pre 1997 management system therefore is far less capable than the 2004 model for example.

We first offered engine management system conversions for 1997 onwards Impreza’s in 1998. These conversions involved modifications to the management system hardware, adding additional circuitry and eproms containing our new fuel, ignition and boost control parameters. These proved to be very popular with conversions for STi 3 & 4, the WRX and 22B.

This modification is rather time-consuming however and due to the age of the vehicles and the high mileages that most have now covered, we can now only offer this service for the 22B models.

All models from 1999 onwards are fitted with a different type of engine management system, which we are able to modify electronically, without adding additional components. We have special computer software produced by a company called Ecutek which gives us full access to the engine management system, and the ability to modify (re-map) many parameters simply by downloading new information into it via the on board diagnostics socket.

Amongst the parameters that we can alter are:
· Fuelling and fuel compensation.
· Ignition timing and ignition compensations.
· Boost pressure and boost limits.
· Turbo dynamics (response).
· Boost based top speed limiting.
· Vehicle top speed limiting (Japanese models).
· Rev Limit.
· Air flow sensor scaling.
· Injector size scaling.
· Check Engine Lamp thresholds for Catalyst failure.

As you can see, this software does give us full access to recalibrate the management system enabling us to release more power from a standard vehicle. We are also able to correctly calibrate it to suit additional mechanical modifications, or re-map an import model for UK fuel.

Raising the power of a turbocharged engine by making modifications to the engine management system is relatively easy process. It is also easy however to put excessive strain on the engine by doing this, which could cause engine failures, plus it is also easy to ruin the driveability of the engine, and it’s on the road manners.

We have been mapping management systems for road and competition use since the 1980’s and it is this depth of knowledge and experience that goes into every conversion that we do.
We take great care to ensure that the mechanical reliability of the engine remains within totally acceptable levels, and wherever possible, we actually enhance the driving experience by improving throttle response, off boost performance and turbocharger spool up.
Although we have a number of ‘standard’ programs for each vehicle and management system combination, when we have the car here we spend a considerable time fine-tuning each conversion exactly to that particular car, and the components fitted. This means that you have a bespoke program that is created exactly for your vehicle, and optimised to suit the components fitted.

Prices

A standard ECU remap (generally + 30 BHP + 35 lb/ft) £695.00

Remap to prevent the Check Engine Lamp coming on because Catalytic converter is removed (no performance improvement) £295.00

ALL PRICES ARE SUBJECT TO VAT @ 17½%