<E28> Found the Culprit it seems.. Re Stalling Rough Idle Ongoing issue

["Ron J" <ron@xxxxxxxxxxxxxxx>]

Hi All,

I have written a few posts about my 85 535i, and rough idle, loss of power,
and issues related to it, when driving back from Florida to Toronto.

Well yesterday it all came to a head.  I was on my way to a meeting in the
morning, and the car started to idle roughly, and would lose power unless I
had the gas pedal pushed all the way down.  While driving, the car would
surge up to 5000 rpm, the tires would spin and the car would start to move
normally, and then as soon as the rpms would settle down, the engine would
stumble, almost stall, and repeat the cycle again.  I was driving down the
road, with my 4 ways looking like someone that doenst know how to drive
standard.  Then all of a sudden I lost brake pedal pressure, and had no
brakes, but they came back, and the car started to behave properly. .  Then
someone in a car beside me started honking for me to pull over, when I
rolled my window down, they told me I had a fire under the car.  I quickly
pulled over and looked underneath, and saw some flames, and put them out
with my fire extinguisher I keep behind my seat.  After I looked at where
the fire was, I noticed it was a rubber hangar from the exhaust system.  I
parked the car, jumped in a cab and went to the meeting.  While at the
meeting I had the car towed over to a mechanic that I know.  I left the
meeting and borrowed a freinds car (beauty 99 mercedes E320) and drove over
to the mechanics, just as the car was being pulled in.  They put the car on
the hoist, and lifted it up, and we inspected the underside, and noticed
that the hanger that caught on fire was right near the gas/brake lines, on
the drivers side of the car, under the rear seat.  That made us realize that
the fire had boiled the brake fluid, causing the brakes to go, so we bled
the brakes, and they were back to normal.  Then we started to look into why
the exhaust got hot enough to cause the hangar to catch on fire.  It was
most likely a lean condition in the engine.  So we popped the hood and
started the car, and it ran fine, and then started to stumble for a brief
amount, and then evened out.  I explained that I had changed the ICV, and
the FPR due to past problems similar to this problem..  We then hooked up a
feul pressure guage to the input feul line, and started the car.  It showed
that the car was running with 30 PSI.  Then thier Mitchell computer program
for the the proper specs, and found that it should be running at 42 psi,
with specific volume that I cant remember.  We went back to the car.  and
checked the guage again.  It was still at 30 psi and the engine was running
fine.  My Mechanic friend advised me that the car wasnt getting enough feul,
and was therefore running lean, which was heating up the exhaust, which in
turn was causing the feul in the same spot to boil, and causing cavitation
in the feul line, which was causing the stumbling issues.  The only issue
was why the PSI was at 30 instead of 42.  We started to think feul pump,
clogged filter.  The filter medium is so big, that we doubted it was the
culprit, so the next possibility was the pump.  Then he decided to call
another BMW mechanic, to talk to him on the phone and explained the
situation, and he said to try the Feul Pressure Regulator.  (the one I had
replaced)   So we went over and used a pair of vice grips to pinch the
bigger line that comes out of the FPR and it made the feul pressure guage
jump to 115 PSI.  It pointed right to the FPR as faulty.  the next thing was
to remove the small vacuum line from the top of the FPR, and when we did the
pressure came up to 40 PSI.  So based on his explanation it is the FPR, its
not opening operating prolerly possibly due to a ruptured inner diaphragm,
or maybe even the wrong calibration.  Which caused the whole loop problem.
car ran fine cold, but when hot, due to lean condition, it would heat up the
exhaust, that would boil the feul line, and cause cavitation, and as soon as
the car would cool it would go away.  makes sense since the condition only
happened when I was on a long drive, or stuck in traffic doing the stop and
go.

So now I have to go the dealer and get another FPR $170 CAD, or $110.00 USD,
and I have a faulty one that I ordered from thepartsbin.com, that almost
burned my car to the ground.  Hopefully they will refund my money, and if
they don;t I will reverse the charges on my Credit Card bill.  I guess the
warnings regarding getting parts directly to the dealer should sometimes be
given creedence, especially regarding feul injection parts.  The faulty one
was made by bosch and all, and just to save a couple of bucks, I ordered it
from an online company, which I understand gets thier parts from World Pac.

So off to the dealer to get the new FPR.... Then on tuesday I change my feul
filter just to be on the safe side.  (too cold and snowy to do it here, so
its getting done at my mechanic friends, along with a valve adjustment)

Cheers
Ron J
85 535i
73 911s 2.7

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