Re: [SIG@M535i] <E28> 535i Hesitation yet again.. Advice?

["Ron J" <ron@xxxxxxxxxxxxxxx>]

Hi Russ,

Would the throttle position switch being faulty and effecting the ICV cause
the problem of the car running that rough?

Another thing I also forgot to mention was yesterday, and the day before
while driving the car (warm) at a light when I let off the throttle, the
rpms would fall to an almost stall point and then catch again, and then
almost stall again, or would stall.  The car would start fine, but as soon
as you stab the gas, the rpms would come back down and go below normal idle
and almost stall or definatley stall.  This happened everytime I got off the
gas.  Once the car was cold, and then restarted the problem would go away,
and reappear as soon as the car was warm again.  I am thinking its
connected, since this rough idle issue today also seems to be evident only
when the car reaches operating temp.

My question is still, would a stuck open ICV valve cause this problem? or is
it just an indicator of something else that is wrong and cuasing the rough
idle problem.

Thanks
Ron J
85 535i
- ----- Original Message -----
From: "russelc" <russelc@domain.elided>
To: <>
Sent: Tuesday, April 08, 2003 6:12 PM
Subject: RE: [SIG@M535i] <E28> 535i Hesitation yet again.. Advice?


> Um,
> The only thing I can see is 2 things, from the history and what you've
just
> said.  If the ICV is open when the car is off the idle switch, then check
> the operation of the throttle position sensor.  From there, I'd suspect
the
> DME.  The ICV should never be open under any condition when the idle
switch
> is false.  No sensor that I know of will open the ICV when idle switch is
> false.
>
> RussC
>
>
> > -----Original Message-----
> > From: Ron J [mailto:ron@domain.elided]
> > Sent: Tuesday, April 08, 2003 2:57 PM
> > To: M535i SIG; BMW; E28 Group; UUC-BMW
> > Subject: [SIG@M535i] <E28> 535i Hesitation yet again.. Advice?
> >
> >
> > Hello All.,
> >
> > Well the saga awakens yet again.. On my way to university to
> > study at the
> > library for an exam tommorrow, the car started to hesitate
> > mildly at first
> > and then more violently until there was no power at all,
> > unless you put your
> > foot all the way to the floor.  Then the tires would spin,
> > and as soon as
> > the RPMs settled it would hesitate again, and drop to about
> > 500 or so.  I
> > pulled off the road, and looked under the hood, and could
> > find nothing the
> > matter.  The engine was idling really rough, and eventually
> > stalled while I
> > was looking under the hood.  I kept tinkering and when I
> > tried to start the
> > engine again, I had a dead battery.  Luckily I there was a
> > guy across the
> > street with a van that gave me a boost.  I got the car
> > started and limped it
> > over to a garage.  The owner seemed to know the cars very
> > well, and started
> > to look under the hood.  he said it was a vacuum leak by the
> > sounds of the
> > hesitation and seemed pretty sure about that.  Anyhow, we
> > tested the battery
> > and I ended up getting a new one.
> >
> > By this time, the car was cool, and it started ok, and idled
> > ok, but as soon
> > as it got warm again, it started the rough idle.  We checked
> > all the hoses
> > and didnt seem to find a vacuum leak.  He then pulled off the
> > (brand new as
> > of January) ICV valve, and said it wasnt working properly.
> > He did a test by
> > looking on the inside of the valve while he had another tech
> > turn the key
> > from off position to on, without starting the car.  The
> > little gate on the
> > inside stayed open the whole time.  The valve buzzed but the
> > gate never
> > closed.  It would budge just a little but stay in the same
> > position.  Since
> > the valve was new, he said that it could be the computer, or
> > one of the
> > sensors near the front of the engine by the coolant intake.
> > Apparently they
> > signal the valve to open/close.
> >
> > As a side note, the hose running from the bellows to the
> > valve cover (1"
> > diameter) with a smaller 1/4 line running off the bottom was
> > cracked.  It
> > has electrical tape on it, and it wasnt leaking, based on
> > what I could see,
> > and what the tech said.  I am going to replace it anyway.
> >
> > He wanted to keep the car overnight and look at it tommorrow,
> > but I said I
> > needed it for exams tommorrow at university, so he said to bring it in
> > afterwards.  He was going to check the signal to the ICV, and from the
> > sensors.  I said I would bring the car back.  I left, and
> > about 5 minutes
> > away from the shop the car started the same behaviour again,
> > and the exhaust
> > got so hot, the rear rubber hanger caught on fire again.. I
> > guess it was all
> > that unspent feul in the tubes.  I put the hanger out, and
> > now the car is
> > parked.  I cant get to my exams tommorrow, and I dont want to
> > try driving it
> > to the shop again.  I guess it will have to be towed in.
> >
> > Any suggestions as to what might be causing this?  New ICV,
> > new FPR (2nd
> > one. purchased from the dealer this time)  New Cap and Rotor, new feul
> > filter, new plugs, valve adjustment, and no visible vacuum
> > leaks.  Could the
> > ICV be causing this bad running condition?
> >
> > Please help
> >
> > Thanks
> > Ron J
> > 85 535i

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