Weird Vibrating Problem!? - BMW Forum

wyldbill · 08-22-2005, 10:19 PM

Hey all,

I'm hoping someone has had this problem before, or has some insight on it. Anyway, i have a 98 M3 sedan with A/T. I have had the car since Oct of last year and haven't had any problems until a few weeks back. About a month ago the car upon start had this heavy vibrating, kinda like what an aftermarket stiff motor mount feels like. It is heavy enough to feel and i can see the rearview mirror shaking pretty good. It does not affect performance at all, and goes away after 10 sec-1 min.

Now here are some things i can only throw out there (grabbing straws). When this first started i filled the car with 87 oct gas a month ago and added octane booster (bad gas shortage here in the Panhandle of FL then). It did it a fews times after that and then hasn't raised its ugly head until today. Been running straight 93 oct since I put in 87 oct. Only other thing I can think is I was low on gas this morning and filled up (right before warning light came on), filled with 93, drove about 10 miles and then it did the vibrate thing a couple times. One time it lasted about a couple minutes. Oh yeah, it does it at idle or moving.

My car has 87,500+ miles on it and besides this problem has been running great.
So, could it have anything to do with the 87 oct a while back, or the tank being basically on a couple gallons and maybe sucking up some particles causing a temporary issue? Sounds far-fetched to me, but I don't have a clue as to what could be causing this.

Thanks for your time...and if anyone has a clue please share!

rizla · 02-23-2006, 03:46 PM

hi mate, you dont say which kind of car you have but i think the octane rating you are saying is quite low. i have an m3 e36 evo and it has a sticker next to the speedo which says use 98 ron petrol i.e. super unleaded or what ever is available where you are i.e shell optimax . it is a bit more expensive but it is a high performance car and should only drink the best!!!!. hope this helps.

4evrwyntr · 02-23-2006, 06:01 PM

The 98 m3 sedan us-spec only requires 91 or higher... Are you sure it's not a motor mount? Does it disappear completely when you start accelerating (only rough when idle)?

MadBMW · 02-24-2006, 03:30 PM

We need more input from you to help. The vibration can come from the wheels, tranny, or motor. When you say "start" do you mean taking off from the line or when you put the key in. If it is just starting the car it maybe something that has to with the belts or alt. bearings going bad. more info and I can help.