I’ve always found this a hilarious subject. You’ll find a lot of tuners who offer ‘Live Tuning’ (they’ll offer to tune your car on a dyno).
I just want to explain something without getting too technical. If you’ve had or are considering getting your car tuned on a dyno, make sure the person tuning the car also has your vehicles factory diagnostic computer.
I’ve come across too many ‘buffoons’ in my time who will ‘rant and rave’ about their knowledge, or how they know how tune a car a dyno. Ok, first of all I just want to clarify that every car has to be tested on a dyno before a tuned file can be created.
So many dyno’s out here are incorrect so, if your dyno isn’t measuring correctly and your tuner has tuned your car on that dyno knowing very well that the dyno is incorrect then guess what?? Your car isn’t tuned properly. What starts off on the wrong foot, you know where I’m going with this. The correct way to create a file is to use a dyno, which measures correctly. If your not happy with the results, delete the adaptation values using the factory diagnostic computer (BMW = GT1, Mercedes = Mercedes Star Diagnosis, Ferrari SD2/3, etc) and start again. For example we were like with many cars in North America the first company to program the BMW M5 E60. After programming the car we then connected the GT1 to see how long it would take for the car to go through its adaptation period, the result was 105.4 miles. What this means is once your M5 has been programmed it will take that many miles for the file to fully adapt, even though you’ll feel the gain right away (the car will get faster and faster as it goes through this stage).