Need help, 740i is shaking.

[BMW740i]

I just recently purchased a 1995 740i and the car for some reason at the stop light will shutter or shake a little. Anybody have any clue? could it be the oxygen sensor? Any help would be great. Thanks

[Maz]

It is most likely the O2 sensors!!! they are cheap to replace and the car runs so much better once they are replaced

[EXtech]

Three things to look at: Crankcase vent valve, valve cover gaskets leaking, catalytic converters. How many miles are on the car?

[TECH]

Originally posted by BMW740i@Jan 26 2004, 12:50 PM
I just recently purchased a 1995 740i and the car for some reason at the stop light will shutter or shake a little. Anybody have any clue? could it be the oxygen sensor? Any help would be great. Thanks

There is no way in the world for any of us to tell you what the problem is.

Oxygen sensors are very unlikely to cause a rough idle on these cars. Crankcase vent valve is a likely suspect (it's actually a plate on the back of the intake manifold), valve cover gasket's leaking-not likely, but possible (sucking air, not just leaking oil), catalytic converter-possible, but it would cause problems above idle as well.
You could be looking at a spark plug, fuel injector, ignition coil, idle valve, intake vacuum leak from various sources, a sensor malfunction of some sort (which would usually set a check engine light), bad fuel, etc.
You can check all these things to the best of your ability, but we can't say for sure what the problem is.

[EXtech]

valve cover gaskets leaking= vacuum leak and oil in the spark plug cavities (misfire)
Catalytic converter can cause problems at idle but have yet to create a noticeable problem above idle (i say this because i've seen it).
Any vacuum leak will cause a rough idle. It seems you should have the vehicle looked over if you don't feel confident yourself. Has your Check engine light come on?

[CLW]

For what it is worth I have a '97 740il. About 2 years ago with about 65K on the odometer it began a subtle miss almost exclusively during warm up idle. Initially it would clear within 3-4 minutes. Felt like a mildly fouled single plug but was irratic occurence wise, not always happening. Gradually occurences became more noticable but still subtle, not enough to really stop and go after. Always at idle and never above 1000 rpm it finally set the check engine light. Took it to the dealer and was the convertors. Funny thing was even at the end it was not every time you started it and almost imperceptable when warmed up.