Should I reset the car's ECU if...
 

...I purchase a 2005 with 8300 miles...which means the previous driver drove ~4000miles/year...and I drive 18k/year...should I unplug my battery to reset the CPU after I buy the car so it can adapt to my driving habit?

Now, if I do plan to take off the battery, any precaution as far as prepping the car? I know I should keep the windows down so when I plug the battery back in, I don't have reset the windows for it to seal when I close the doors....or was it the other way around???

The ECU will adapt to you no matter what you do. You don't need to do reset it.

As for unplugging the battery, you don't need to prep anything.

Sure, you can go ahead and unplug the battery overnight. You don't have to, but it can't hurt either.

If you don't open or close the doors while the battery is unplugged, you'll be fine.

If you need to open or close the doors while the battery is DC'd, just lower the windows 2 inches

I know the ECU will adapt, but with the car been driven only 8000 miles in 2 years, how long will it take for it to adapt to my driving?

~200 miles-ish

so why is it that my car, after i added a 5/16'' spacer adapted so well i get worse mpg?

multiple possible reasons, most likely is your driving habits changed without you realizing it.

is it recommended to reset the ECU after adding an exhaust/headers/plenum spacer?

Maybe you unknowingly are harder on acceleration now that you've increased performance.

no. total waste of time

Actually there are 3 adaption: one is short term where it adjust every few rpms, the next takes 5 minutes and the extreme long term might take an hour at 60 mph cruise.

WOT throttle adaption is very very fast otherwise the engine would be at risk.

Reset just reverts [forgets] any trims and normalizes to the preprogrammed parameters.


Everyone thinks reseting is magic when it does very very little unless you were throwing a MIL code and repaired a sensor.

No, but tuning is.