[ZBMW]

About a week ago, while launching from a stop my V4 equipped 07 335i did a sudden rattle, similar to what happens when a car bogs down from lack of revs when releasing the clutch. I thought I had added enough throttle and my launch technique was no different than usual. For slow starts I sometimes just slowly release the clutch without applying throttle and the engine torque is more than adequate. I thought of it as a one time event but the other day the engine did a sudden, transient seize as I was shifting into second, almost as if one cylinder decided to predetonate. I instantly let up on the gas and engaged the clutch but it shook me because nothing like that has happened with the otherwise smooth N54. No codes are showing, the oil was changed very recently and the plugs have about 1K on them.
Anyone else have this kind of experience?
I thought the electronics made this kind of thing impossible.

[OpenFlash]

Originally Posted by ZBMW

About a week ago, while launching from a stop my V4 equipped 07 335i did a sudden rattle, similar to what happens when a car bogs down from lack of revs when releasing the clutch. I thought I had added enough throttle and my launch technique was no different than usual. For slow starts I sometimes just slowly release the clutch without applying throttle and the engine torque is more than adequate. I thought of it as a one time event but the other day the engine did a sudden, transient seize as I was shifting into second, almost as if one cylinder decided to predetonate. I instantly let up on the gas and engaged the clutch but it shook me because nothing like that has happened with the otherwise smooth N54. No codes are showing, the oil was changed very recently and the plugs have about 1K on them.
Anyone else have this kind of experience?
I thought the electronics made this kind of thing impossible.

I don't know about you, but I always dig into the throttle slightly when I take off from a start. It doesn't take much to stall or rattle an engine if you don't do that.

shiv

[ZBMW]

I agree fully. But, in both of these events, I was applying throttle and, in the most recent one, I was moving and shifting into second gear.
I'm well into my 3rd year with this car and this is something new. Before checking with the dealer I wanted to verify that this was not something that occurs occasionally. I've read about and incurred a dropout in power but this was not like that - it was pretty violent. I was surprised it didn't show some code, considering how sensitive the electronics are.

[OpenFlash]

Originally Posted by ZBMW

I agree fully. But, in both of these events, I was applying throttle and, in the most recent one, I was moving and shifting into second gear.
I'm well into my 3rd year with this car and this is something new. Before checking with the dealer I wanted to verify that this was not something that occurs occasionally. I've read about and incurred a dropout in power but this was not like that - it was pretty violent. I was surprised it didn't show some code, considering how sensitive the electronics are.

If it's a new thing that suddenly started after 3 years, there is definitely something going on. Could easily be a fuel pump. You just might have to keep driving until you throw a code at which point just drop it off at the dealer.

[vase330]

That or maybe bad gas? Go get gas from a station after the gas truck has just pulled away, you will be surprised what happens until that tank is gone. Usually you have lots of swirling dirt and even water in the gas.

[ZBMW]

Thanks guys. Both good guesses. I'm leaning to the HPFP too. My regular gas station pumps sunoco in large quantities so I'm guessing that their tanks should be clean.
Just have to wait!