shaking/shuddering/vibrating while driving cold but smooth idle - any ideas?
Already tried the search function, this problem seems to be slightly different than what most people have.
2001 330xi w/ 96k
The issue is that on a cold start (35F the other day) the car will shudder while driving until the engine heats up (cruisin at about 30 mph in 3rd gear at 2000rpm shuddering is at its worst). Contrary to most people's posts, at idle its perfectly smooth and quiet; I only notice the problem when the engine has a load on it (as soon as I take out of gear the shuddering goes away). Also, as the engine temp warms up the problem completely disappears. I just replaced the fuel filter (shuddering was there before and after) and the spark plugs were replaced 10k ago (as well as a swapping of the ignition coils to address a rough idle). Also, filter service and oil change was done 3k ago.
Problem fixed (I think) by replacing pre-cat 02 sensors. Most likely that a heater in one or both of the old ones was broken so they wouldn't operate optimally until engine temp was high enough.
Last edited by msb046; 02-15-2010 at 07:34 PM.
Reason: Solution found