Why would the vehicle manufacturer de-tune the engine, when they appear to be constantly chasing fuel economy and performance?

Here are the facts:

All modern cars and CRD (common rail diesel) vehicles, both car and 4wd’s, contain an ECU (Engine Control Unit) that is effectively a small computer which controls how the engine works. Vehicle manufacturers de-tune the engine by setting the ECU software to a default setting before sending the vehicle out.

Due to the manufacturers having to sell their cars all over the world; the software settings in the ECU must take into account different climates, laws, restrictions and varying quality of fuels, not to mention in-house politics that governs a price jump from one model to the next. (Just so happens, this NEW more expensive model has more horse power than that one). You’re led to believe this new model has an engine upgrade, when it is only upgrade is an ECU remap.

Vehicle remapping is basically the modification/replacement of the manufacturers default software in a vehicles ECU.

See below the different power and torque figures all from the same 4WD. This is all the same engine that has been “tuned” for different power and torque figures. Now there are a lot of reasons why engines are tuned or de-tuned, some are obvious and some are not.  Be assured that the manufacturer has not fitted, in this case 5 different engines in the one model of 4WD. They have simply had different tune files uploaded to the ECU.

Now some of these reasons (the obvious), could be simply one model may be a rear wheel drive, another, a 4 wheel drive, whilst others may be automatic’s or manuals.

Then you have the (not so obvious), one model could be sold as a base model and low power, then you have the “up spec” model with more power and of course, a little more expensive. (Again, they didn’t put a new engine in to get the power increase; they just changed the tune file).

You might be surprised to find that some manufactures will even “de-tune” an engine if they have had too many warranty claims, say for example a slipping clutch. You see, it’s more economical for the manufacturer to “de-tune” an engine, (reduce power and torque) which can stop the clutch slip and reduce or stop any warranties. This process would cost them close to nothing as opposed to re-designing a new clutch, not to mention, what would they do with all the clutches they have already purchased or pre-ordered? (Now that would be costly).

So, as you can see, there are a lot of reasons why a manufacturer may “de-tune” an engine.

Nissan Navara D40 YD25 intercooled turbo-diesel, DOHC.

Max power (Kw@rpm) Nissan Navara D40






Max torque (Nm@rpm)





Remember, all this is the same 2.5 Common Rail Diesel engine.

And another. Here is a clip from a magazine from when this Audi was released.

Audi has clipped the wings of its next performance car, de-tuning it to suit Australia’s climate.The turbocharged, all-wheel-drive S3 Sportback is a rival to the likes of Subaru’s Impreza WRX STI and the Mitsubishi Lancer Evolution, a car that according to Audi offers “uncompromising performance”.

But Australia’s S3 has been compromised to suit our climate. Audi spokesman Shaun Cleary says that the car will have 15kW less than European models. “There will be a lower power output just for hot weather countries,” he says. “The power output will be 206kW while the European car has 221kW.”But Cleary says the performance has not been blunted as the car will still offer a peak torque figure of 380Nm.
“The torque is the same and the acceleration is the same to 100 km/h, which is 5.1 seconds,” he says. A 221kW S3 would have matched Subaru’s renowned WRX STI for power, and held an advantage over the Lancer Evolution, but the Audi will now trail its Japanese rivals.

This is not the first Audi to have been de-tuned for Australia. The previous-generation S3 and current Volkswagen Scirocco R were both de-tuned from 195kW to 188kW before going on sale locally.

So, do car manufacturers DE-TUNE their cars? YES!

Can we RE-TUNE them and make them go better? YES!