Car goes through cycles

[bkfastwagon]

A strange observation that baffles me: my M3 (the engine to be more specific) seems to be 'bipolar.' Every 600-700 miles the engine switches between feeling strong and smooth (what you would expect) to feeling slightly rough and not as willing to rev. It's not a huge difference where one would suspect failure but noticeable enough to be annoying. Come to think of it I think my f80 m3 did this as well. Is this ecu adaptation? No fault codes. No CEL. Seems unrelated to humidity, temperature or gas. Any thoughts? Thanks

[MJBO]

My car feels a little bit like that at times, mostly feels like a bipolar gearbox in mine though. Nothing feels problematic, just different from time to time.

Definitely feels worse when it isn’t being driven regularly and getting a little bit of high rev action. My E46 M3 was the same, needed a goo regular revving or it just didn’t feel right.

[kyippee]

Take it to a track day, italian tune up

We removed my spark plugs recently and things are surprisingly clean. I think the track driving helps clear up any deposits

[LuckiSevens]

Originally Posted by bkfastwagon

A strange observation that baffles me: my M3 (the engine to be more specific) seems to be 'bipolar.' Every 600-700 miles the engine switches between feeling strong and smooth (what you would expect) to feeling slightly rough and not as willing to rev. It's not a huge difference where one would suspect failure but noticeable enough to be annoying. Come to think of it I think my f80 m3 did this as well. Is this ecu adaptation? No fault codes. No CEL. Seems unrelated to humidity, temperature or gas. Any thoughts? Thanks

Read the books that came with the car, it says when all of the engine components get too hot, the ecu is programmed to reduce engine power until temp comes back to a more normal range... that could be the issue

[cjm41]

I'm convinced every few days someone swaps my car out for an identical clone that runs differently. I even have an exhaust leak that kind of comes and goes.

I've blamed it on the crazy Florida weather. It goes from 50 and dry to 80 and swampy overnight during the winter.

I do have a BPM Stage II tune, no cats, full exhaust, so there are some non-factory variables as well.

[SAMM3Y]

Originally Posted by cjm41

I'm convinced every few days someone swaps my car out for an identical clone that runs differently. I even have an exhaust leak that kind of comes and goes.

I've blamed it on the crazy Florida weather. It goes from 50 and dry to 80 and swampy overnight during the winter.

I do have a BPM Stage II tune, no cats, full exhaust, so there are some non-factory variables as well.

My car stinks like leak too sometimes. I'm running a stage 2 with HFC's. I even went as far as switching my catless out for hfc's cuz I hated the smell. Have searched a few times for a leak and can't find one or hear one. Must be a valve that ventilates to atmosphere in the engine bay somewhere? Smells rich and fumey when it happens to me..