dragging up an old post (as I just quoted this post as evidence a simple AIT offset can improve drivability, a lot of cars with euro 5 are becoming undrivable)
but then reading some of the points raised there is some serious misinformation posted.
A bike with a booster plug fitted can't learn and compensate out what it does. It doesn't work like that ever.
A bike with a booster plug only impacts for short duration throttle movement below 4k rpm - after this it has no impact on steady throttle application or higher rev engine management at all
All it does is offset the AIT (air temp intake sensor) and trick the bike in to thinking its a bit colder than it really is, so at low revs on a constantly varying throttle (round town, on off throttle, exactly where an overly lean mixture causes seriously rideability issues) it brings in a colder weather fuel map richening up the mixture a TINY bit. As soon as the flow over the CAT sensor is sufficient and stable enough the booster plugs impact is totally negated.
On the K25 boxer engine the std fueling is a sick joke that is so poor you could take a swig of petrol and spit it in far better than BMW does it. Mine was unridable below 3250 rpm (unless you are a mechanically inept animal trying to break the final drive and want to see if the instrument cluster can literally vibrate off the bike). I fitted a powercommander and can now happily ride at 1500rpm and pop the front wheel off the ground by 3k. The difference is incredible.
I put a posh booster plug on a euro 4 adventure LC, of course you can feel it working (but its very subtle) - however the nanny state electronics are mostly winding off the power whilst the booster plug is trying to help. Enduro pro mode is the least bad setting if you understand what the right hand grip is supposed to be for.
The "proper" booster plug has a separate ambient temp sensor that should be fitted in the air flow at the front of the bike so that the AIT offset varies according to ambient temp conditions. What you want is a richer mixture than BM offer, not force it to continuously believe the full cold weather map must be used at all times. That's the difference between a budget AIT offset device, rather than the current "booster plug"
This may well be true if it is publish in a non-BMW forum.
However, for the BMW ecu a "proper" boosterplug is the one you place in the trashcan.
Whatever compensation to the fueling the boosterplug may offer, the O2 sensor will sense the richer mixture and readjust the fueling to get it back on track (Track as in AFR 14,7). Whenever the ECU operates in closed loop, the compensations required by the O2 sensor also gets stored in the adaptive table (long term trim in non-BMW language). The long term trim strives to be the compensation value that adds/subtracts fuel to where the realtime compensation from the O2 sensor is 0 (short term trim).
The long term trim is also added in open loop conditions, thus if the engine e.g has a clogged airfilter the engine will also have a descent fueling during open loop conditions.
Therefor, you will notice the boosterplug in the beginning after it's installed, and then, ever so slowly the long term trim table gets adjusted, based on feedback from O2 sensor in closed loop conditions, and the eventually the effect of the boosterplug is neutralized.
The ugly part, in my opinion, is that the sellers of the different devices spend a great deal of effort to explain the wonder of their product, and then conveniently omits the crucial information that actually torpedo the use of their product.
I can not rule out that the boosterplug was able to make the fueling richer beyond the range of the adaption capability on early systems. But the lates systems do have such a large range that the richening has to be quite heavy in order to not be overridden by the ECU. If you push the latest ECU to its maximum compensation values the engine will run quite rough.
I've seen one company that even mention the adaption as an impossible feature and claims it is BS and false rumors set out to hurt their business, neglecting that Bosch introduced adaption in Motronic 2.2 (late -80s) BMW introduced the O2 sensor early -90 and their systems have been adaptive ever since.
