Hello folks, I am new to the forum so please be gentile. This is my second E46, the first was crashed. Both cars had the same anomaly. When I am stopped with the car in gear periodically the idle will briefly dip below 5400 RPM shacking the car then go right back up to where it is supposed to be. This happens about a couple of times a day but not often enough to replicate it for a dealer service technician. Anyone else experience this? Any ideas? Thanks.
IIRC sporadic idle surging/hunting was a common complaint on certain E46's. In my case there was a service bulletin to correct it that involved replacing the switch module for the heated seats. It's been fine ever since. You could ask the dealer about that (if you have the bun warmers), and/or try playing with the electrical load to reproduce it: heated seats on high, blower on high, rear defroster on, lights on, radio on, etc.--try individually, all at once and various combinations. If you can't reproduce it at will, the next best thing is to keep careful notes of the car's state when it occurs: cold or at operating temp, in stop & go driving or only after a long highway run, ambient temperature, in gear/in neutral, level ground/inclines, etc. -- anything you can think of. Enough data can help a good tech spot a pattern and decide which systems to test even if they can't reproduce the problem.
Thank you. It happens all the time and now happens 3 or 4 times while sitting at a light. It also happens to a lesser extent in neutral. I will get it to a dealer. Jim
my 325xi does the same thing My 325xi does the same thing. It is a 2004 manual trans, wagon and it usually only occurs when it is cold outside and it has not fully warmed up. I performed a very extensive 100,00 mile service last year on it that included plugs, water pump, expansion tank, pcv-crankcase vent valve, DISA valve, belts, hoses, various vacuum hoses etc. The computer has been re-flashed at the dealer, and they have tried to analyze it severla times, all to no avail. The wild idle occurs at temps in the 30s and will range between as low as 500 rpm to as much as 2,500 rpm. It will eventually calm down when it warms up. One of the replies to your post mentioned the possibility of a link to the seat heaters being on, which mine are ALWAYS on at cold temps (getting old I guess!). I will try it cold without any heat (seat or HVAC) on to see if it happens. It happens all the time and now happens 3 or 4 times while sitting at a light. It also happens to a lesser extent in neutral. I will get it to a dealer. Jim[/QUOTE]
Have any of you looked into a potential vacuum leak? Vacuum leaks commonly cause running problems, including idle.
