German Car Forum

In an effort to address specific noise concerns, BMW in the United States updated the turbocharged engine software on 335i/xi and 535i/xi models built from June 2006 through March 2008. However, the updated software caused a small amount of increased turbocharger lag under certain circumstances, which BMW confirmed is noticeable and now plans to address by releasing a new update.

Release of the new software to restore the original turbocharger response is planned for January 2009, and it will be available for vehicles produced from September 2007 through March 2008 when they are brought to an authorized BMW center for a repair that requires a programming update.

Owners with vehicles produced from June 2006 through September 2007 may also request installation of the January 2009 software update. However, BMW states that changing to new software may increase engine noise levels under certain circumstances.

Other vehicles that use the same N54 3.0L twin-turbo six, such as the X6, 135i, as well as 3-series and 5-series models produced from March onwards are not affected. Earlier this year, a global panel of judges awarded the 300hp N54 as engine of the year, picking it for its flexibility and mix of performance and fuel-economy.


Source: BMW acknowledges N54 engine turbo lag, releases software update - MotorAuthority - Car news, reviews, spy shots

I wonder if they will just give them the full 330hp and 450nm as well?

..well,why would they?This update is free of charge,as far I can see,right?

That's only stage 2 tuning. The engine can and will be updated until stage 3 if required...

Anyone can crank up the power of a turbo charged engine very easily. But if you do so you'll negatively be affecting reliability, response, delivery as well as fuel economy. BMW obviously don't want the engine to be a lagger which and has thus found the balance between what I mentioned in my previous sentence, to be 300hp.

^ Bum man is talking about the 330 hp 740i (135tii) engine I think.

^Yup, it was meant to be a joke. But then again I think some compensation is in order.

It's all down to software parameterisation. The physics aspect pertaining to low rev-range response is addressed by the mechanical characteristics of the two, small, low-inertia turbos fitted to the N54. The delivery and maximum output is governed by ECU parameters that control turbo wastegates (boost pressure) and so on. So a 10% increase in horsepower need have no ill effect on low-down engine response if the same mechanicals are used - it's just a case of leaving the wastegates closed for a tad longer to build up slightly higher pressure.

According to most dynos, the engine is already making 320+ Hp in 335/135. It is just a matter of what they print in the catalog.