Originally Posted by Bob MG
I do love this statement. Have you ever had a good tune on one of your cars?
On a turbo car it adds massive gains. Especially in mid range. With this attitude I'm surprised you didn't just go for a 550i
If you going to tune, then ensure you are doing it with a reputable tuner and also that the speed governor and rev limiter are left untouched.
BMW have no other way of detecting the tune without those parameters being exceeded.
I did this on my last ESS supercharged E90 and when the car went in for quality inspection when everything was bolted off, they found nothing and it passed with flying colors
Once you exceed the speed limited or rev limiter you can never erase without replacing the instrument cluster as well as clearing all other DME's
Going over the governed 250 KPH and the factory RPM seems stupid anyway
There is a BIG difference between a service and a warranty claim. At a service, the info available to the technician will not tell him if there has been a tune present (in the case of a piggyback). If you have had a ECU flash and reflashed back to std. software, all they can see is that at a certain time there was a bunch of fault codes created. If you have a fault code eraser you can avoid that as well.
But, what they look at during a service is just scratching the surface of what the DME have logged. The dealership won't normally have access to read and/or analyze that info however, and in a normal service situation don't need to anyway.
But for a warranty claim involving, say, a engine replacement the dealership will have to turn to BMW HQ for a decision on whether this is a failure covered under warranty or if it's due to driver abuse/non-original software etc. That will be a MUCH more in-depth dive into the DME and engine than they do at a service.
In fact, it would be rather stupid of any manufacturer not to create some sort of logging that will help them decide if someone has tuned their car. Otherwise they would risk having to cover failures that some wonky aftermarket tune might have caused...