So there's been alot of speculation as to why Lexus Middle East detunes certain models for our region.

Lexus GS460 in North America for example are rated at 342hp. While here they have been detuned to 322hp.

The GS460 is not Direct Fuel Injection, so one can only assume this detune was done for marketing reasons only.

So I decided to dyno the car to see what is going on, and indeed... not surprisingly... we found out for certain!

Here's my write up from a Lexus forum:

Okay boys, I dynoed the car last night on a dynojet. I must admit, it wasn't as tricky as I had feared it to be.

So here it goes, got the car on the rollers, got her all set up and strapped in place.

Power button on simply because I really wanted the car to delay shifts, give me a more accurate and sensitive throttle indication and finally... hold gears!!!

Traction control fully switched off by depressing the traction button for 5 seconds.

We don't have snow mode here, all we have are the ECT power button. Kindly observe below picture.



Now the secret to getting the car to hold gears is to linearly apply throttle, shift at just below 4000rpm and once you get up to the desired gear ( in this case 5th gear )... let off slowly so it falls by about 500rpm and apply a relatively aggressive throttle punch all the way down to the kick down button. The car did not downshift and stayed in gear!

Now before I show you the dyno chart, I want you guys to pay attention to my A/F ratio! Lexus Middle East have detuned our GS460's from 342hp to 322hp simply because they were forced to detune the LS460's due to Direct Fuel Injection not coping too well with our pump fuel. So basically, detuning the GS460 was a straight out marketing nonesense!

Our cars are running so rich due to this detune, it is literally choking our cars and depriving us of 20hp if not more! There must be some way I can get my ECU retuned again... there must be!

Here's the dyno chart



And here's the video of the dyno run! Enjoy!

YouTube - 2009 Lexus GS460 Dyno

 

Cheers for the info COB and thanks for sharing!

 

The car is running rich probably because of the climate this car operates in. Excess fuel acts as a cooling agent in high heat environments. You could certainly pick up 20 more hp by having leaning it out a little.

 

To put your theory to test, we are going to dyno a 2007 GS430 and observe the A/F ratio! This way, we will know whether the extra fuel is due to weather provisions or what I beleive to be an exception to the GS460's only.

I have no idea if the ECU on my car can be accessed or tuned? No tuner has yet confirmed they are able to on the 2009 3GS V8 models!