In Reply to: ~~~ENGINE SOUND CHANGE AFTER 4K MILES~~~ posted by 323iT on October 19, 1999 at 01:00:37:
I couldn't believe it when I saw your post. You see, for the past 1.5 years I've been doing a personal survey on two items; one of which you just mentioned. It seems that at exactly 4000 miles something wonderful happens to OBD II bimmers. A noticeable increase in power and the different engine sound as you've just mentioned. I noticed it on my 98 E36 and 3 other people I've talked to noticed exactly the same thing. Its so different at 4K miles that I liken it to someone flipping ON the "full power" switch. I suspect there is some factory programming on OBD II bimmers that limits full throttle conditions such as fuel and spark advance until the car gets to 4K miles. Thus the different engine sound as-well. This is probably why dealers kind-of gloss over the BMW break-in period. i.e. The computer won't let you run the engine 'all-out' until you get to 4K miles. Just my $0.02.
: My 323i engine sounds different the past few days. Does any body know if the engine sound change after how many miles??? I hit 4000