While this seems to make some degree of intuitive sense, given the computerized management of today's engines, I'm not sure I understand exactly how an ECU would manage this unless it was always aware of the vehicle's mileage, which would involve being tied into the odometer in some way. Without such a tie to the odometer, if one were to swap an ECU, or even disconnect battery power for a period of time, it would stand to reason that the new ECU would either need to "read" the mileage of the car or be "told" what the mileage was, lest it go in the car and run in "break-in" mode. (Of course, if an ECU had on board battery or held the mileage data in non-volatile memory, a power disconnect would not affect things.)

This is the first time I've heard this kind of alternate mapping was being employed by manufacturers to manage break-in periods.

My wife opined that it's all in my head, which if fine with me if that's the case! (The other day we had to drive separately to work, and my wife blew past me in the turbo Outback with our 4-year old son on board. As she did this, he tells her "Daddy's white car is slow as a turtle, mommy!" Later, though, he said he liked "the white car" better. To be honest, I could start a whole thread dedicated to the goofy things he says about cars - he's a riot.)

 

I see this thread has veered completely off my point, hehe. Let's create a new title if it's gonna stay in this direction.

 

The odometer and ECM are tied together in the newer Hondas. If you replace the odo it needs to be coded to the VIN number as well as all the data from the old odo downloaded to it. The odometer talks to the ecm by way of BCAN communication...this is also how the maintenance minder system gets all it's info....

 

we may be going towards a different topic, but I'm going to agree with CrystalFive that there is a noticeable difference in an engines performance after break in. The break in period is so that engine internals all seal properly, specifically the piston rings (no-brainier). After a proper seal, yes, there is a noticeable difference in performance, and 500 or 600 miles (break in period) is not a magical number that says your going to feel this difference right after break in, and it also depends on driving habits (some may have a very noticeable difference, some won't). There are definitely performance gains after break in, as well as loses in some cases, it all varies between the drivers and cars and how they are driven during break in and then some.

Oh, and he said "palpable" people!

 

Interesting - good to know.

Audi's have a maintenance reminder system, as well, but I have to be honest and admit to not knowing exactly how it worked in so far as monitoring time & mileage since the previous service. All I know is that the ECU's were swappable w/o any special actions being taken. Maybe once they were in they picked up the current mileage in a similar way.