<E28> Need Diagnostic Help.. 535i running rough

["Ron J" <ron@xxxxxxxxxxxxxxx>]

Ok,

So far, It has been suggested that it could be :

Coolant temp Sensor
Clogged injectors
Cold Start Injector.

I havent ever removed the injectors or cleaned them.. I bought the car last
March, and have only done a few things like exhaust, ICV, FPR, K&N filter,
and oil changes other then that its been cosmetic stuff.

Would the coolant temp sensor cause the car to suddenly jump the idle up to
1500 and hold it there?  I am wondering why giving throttle seems to make
the car stall out when its doing that.

Same question with the injectors.  If the car is idling high, then I would
assume the injectors are working well.. but you try to add throttle, and it
stalls out.    When driving, and the issue occurs, the car just starts to
buck and miss.  So it could be that the injectors are the culprit.

Any way to narrow this down?

Cheers
Ron
- ----- Original Message -----
From: "E Baumeister" <erickbau@domain.elided>
To: <bmw@domain.elided>
Sent: Saturday, January 04, 2003 1:18 PM
Subject: Re:<E28> Need Diagnostic Help.. 535i running rough


> Ron,
>
> Have you ever replaced the main relay? That cured this problem on my
former
> '88 535ia
>
> Erick Baumeister
> BMWCCA 131280
> Tracy, CA
>
> > Date: Sat, 4 Jan 2003 11:06:40 -0500
> > From: "Ron J" <ron@domain.elided>
> > Subject: <E28> Need Diagnostic Help.. 535i running rough
>
> > On the way back the car started to behave strangely.  It initially
started
> > when the car was idling.  It would stay at the normal idle speed, and
then
> > all of a sudden on its own surge up to 1500 rpm, and stay there steady.
If
> > you tried to hit the gas the car would almost stall out.  Then the RPM
would
> > settle down and the car would be fine.  Then in Kentucky I pulled into a
> > subway to grab a snack for our 6 year old passenger.  When we got back
out,
> > the car wouldn't start, like it was out of gas, even though we had a
full
> > tank.  I continued to turn the engine over and the car finally started
up,
> > and we drove away.  Then while on the highway in 5th gear running at
about
> > 2000-3000 rpm doing about 70 mph, the car would start to stumble, like
it
> > was either losing spark or running out of gas, and then catch again.  I
also
> > noticed the fuel consumption guage start to act strangely.  Just before
the
> > car would start to act strangely, the feul consumption guage would start
to
> > climb up really high.  (The car has metric guages so its measured in
> > litres/100kms.  1 gallon is approx 3.8 litres, and 1 km is approx 0.6
> > miles. ) the guage would swing from a normal 9 ltrs/100kms to over
25/100,
> > and then the car would stumble.  This makes me think that the car is
being
> > fed too much gas.  I dont know how that guage works, or what it measures
for
> > its calculation.  But its saying that the feul consumption is way off
the
> > chart whenever the stumbling starts.    The car would do this
intermittently
> > all the way back to Toronto Canada.  Sometimes it would do this steadily
for
> > 10 min and the sometimes only 1 or two times in 20 min.  It wasnt
> > consistent, and the only precursor was the feul consumption guage.
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