Is my engine "knocking"?......

[ryan roopnarine]

it seems that as of late, i've experienced a increase in the severity of engine ping, perhaps related to the outside temperature and crappy 93 gas....i think i might take out mark's chip until i get things straightened out. I know what ping is, which is occuring mainly around 17-2400 rpm when accelerating. recently, however, the car has started making a pronounced "throaty" sound...when accelerating, the car makes a sound like a low octave gargling resembling the noises that come out of a v8.. my exhaust is in rough shape, so i don't know if its related to this. There's a sheered off bolt in where the exhaust manifold connects to the rest of the exhaust, that might be a contributor. Can anyone tell me if this is "knock" or not? I was under the understanding that knock sounded like a wrench hitting concrete, or the noise an engine makes right before it runs out of gas.... TIA.

[Warren N.CA]

causing the heat shield to vibrate in its own mode (at its own resonant frequency).

If you have pinging as well, you may be able to clear it with an "Italian Tuneup." Run the engine on the freeway, in a lower gear at 5.5- 6K RPM for one to two minutes, to blow carbon deposits out of the head. This is REQUIRED periodically with my 535i, or else pinging will develope and worsen, if not attended to. (It doesn't matter whether I'm using the EAT or stock chip, it will still happen.)

it seems that as of late, i've experienced a increase in the severity of engine ping, perhaps related to the outside temperature and crappy 93 gas....i think i might take out mark's chip until i get things straightened out. I know what ping is, which is occuring mainly around 17-2400 rpm when accelerating. recently, however, the car has started making a pronounced "throaty" sound...when accelerating, the car makes a sound like a low octave gargling resembling the noises that come out of a v8.. my exhaust is in rough shape, so i don't know if its related to this. There's a sheered off bolt in where the exhaust manifold connects to the rest of the exhaust, that might be a contributor. Can anyone tell me if this is "knock" or not? I was under the understanding that knock sounded like a wrench hitting concrete, or the noise an engine makes right before it runs out of gas.... TIA.

[ryan roopnarine]

thanks for the followup warren....but i sincerely doubt its carbon issues...i ran a can of bg 44k through it before taking it on a 1400 mile trip, bottle techron for the return 1500 mile trip...and now the car can get solid 31 mpg at between 65-70, i doubt there is any carbon in there if its running at that efficiency. i do occasionally take it on back roads in second or third gear, whatever speed is necessary to get the rpms to hold at 5k for a couple of minutes, doesn't seem to have the same effect that it once did.

causing the heat shield to vibrate in its own mode (at its own resonant frequency).

If you have pinging as well, you may be able to clear it with an "Italian Tuneup." Run the engine on the freeway, in a lower gear at 5.5- 6K RPM for one to two minutes, to blow carbon deposits out of the head. This is REQUIRED periodically with my 535i, or else pinging will develope and worsen, if not attended to. (It doesn't matter whether I'm using the EAT or stock chip, it will still happen.)