98/540ia rough when cold

any ideas on why my 540 is running rough until it gets up to temp ? - when i
start it in the morning below 45 degrees outside it runs rough and wont take
the gas (coughs and sputters) until i get up to 2700+rpm,,,, 1 mile down the
road its warm and life is good...

I tried unplugging the MAF to see if it would run with default settings but
it ran worse... plugged the MAF back in after a qtr mile and still runs the
same ... no engine codes no CE light --

O2 sensors maybe ?

Did you check for air leaks along the air intake path? You didn't say
when it started to run rough but did anyone perform maintenance in the
engine compartment recently? Maybe they bumped something or left a
loose clamp. Could also be a crack in the hose connection.

I think a bad O2 sensor would cause driveability problems all the time.
But the O2 sensor can also cause similar transient symptoms if you had
previously parked the car and stopped the engine just after it was
running rich.

With an air leak, the problem usually goes away after the engine warms
up. Aside from rough running it would idle very poorly when cold.

My 540i6 did something similar one time when I was parking it outside
on hot humid days.

I've always heard the BMW V8's just do that sometimes. I think it has
something to do with VANOS.
Richard
"zz" > wrote in message ...
> any ideas on why my 540 is running rough until it gets up to temp ? - when
i
> start it in the morning below 45 degrees outside it runs rough and wont
take
> the gas (coughs and sputters) until i get up to 2700+rpm,,,, 1 mile down
the
> road its warm and life is good...
>
> I tried unplugging the MAF to see if it would run with default settings
but
> it ran worse... plugged the MAF back in after a qtr mile and still runs
the
> same ... no engine codes no CE light --
>
> O2 sensors maybe ?
>
>

Check you gas.
"zz" > wrote in message ...
> any ideas on why my 540 is running rough until it gets up to temp ? - when
> i
> start it in the morning below 45 degrees outside it runs rough and wont
> take
> the gas (coughs and sputters) until i get up to 2700+rpm,,,, 1 mile down
> the
> road its warm and life is good...
>
> I tried unplugging the MAF to see if it would run with default settings
> but
> it ran worse... plugged the MAF back in after a qtr mile and still runs
> the
> same ... no engine codes no CE light --
>
> O2 sensors maybe ?
>
>

"George Johnston" > wrote in message
.. .
> Check you gas.
>> O2 sensors maybe ?


O2 sensors would trigger the "check engine" light.

i run 93 octane... its there a choke type mechanism or rich fuel mode for
cold starts??

..


"George Johnston" > wrote in message
.. .
> Check you gas.
> "zz" > wrote in message
...
> > any ideas on why my 540 is running rough until it gets up to temp ? -
when
> > i
> > start it in the morning below 45 degrees outside it runs rough and wont
> > take
> > the gas (coughs and sputters) until i get up to 2700+rpm,,,, 1 mile down
> > the
> > road its warm and life is good...
> >
> > I tried unplugging the MAF to see if it would run with default settings
> > but
> > it ran worse... plugged the MAF back in after a qtr mile and still runs
> > the
> > same ... no engine codes no CE light --
> >
> > O2 sensors maybe ?
> >
> >
>
>