rough idle and poor accerlation

[v8mb]

My 1991 525i has begun to idle rough when cold and has a lot of hesitation when accelerating from a stop. When I accelerate slowly everything is good, it only happens when I step on it. Once it gets up to around 30-35mph everything smoothes out and runs fine. Accelerating when moving is fine, it only happens when starting from a stop. I just replaced the flex disc on the drive train, it was in need of replacement, but the above symptoms still occur. Any help? --Vince

[server_bmw]

Yep...
In fact vince, i have had the same problem recurring. This could be due to many problems man - namely: (provided you have an m50 engine inline v6 - 4 speed manual sport / automatic transmission)
- your coil(s) probably went bad and need replacement
- your coil heads (the ones that actually connect to the plugs) have holes in the them and hence do not carry enough charge from the spark. The reason you can accelerate slowly is because you're not applying a great load of pressure on the plugs and they can gradually adapt to the small increments of pressure when increasing speed. However, step on that baby during a drag race (i.e at a red light trying to impress a lady friend in a honda accord - since that is what they all seem to be driving these days - along with toyota camrys) and your car sputters and coughs and shivers like she was running on west nile virus.
- or - You need to clean your fuel induction system (do you have any symptoms like discrete rough idling?) and replace some hoses.
- one of your vavles are going bad and do not open well.

All of the above repairs (except the latter) can be done by you. SO open up that bavarian (m50 engine - sport 4 speed manual and automatic trans - right?) and start working - trust me you will see what i mean. If the symptoms persist - then your guess would be as good as mine. Get back to me asap with your results.
god speed
-server-
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[jeffreyb4me]

Hi Vince, 'server's tips sound good. The problem will be ID'ing the defective coil if there is one. A visual inspection might reveal a 'bubbled' coil casing. DO CHECK the sparkplugs while you have the coils off and the coil boots. If you find oil in the plug wells, you'll need to reseal the cam cover.
keep us posted, [these are all do-it yourself otems]. best to you.