<E28> Hesitation in 535i

["Ron J" <ron@xxxxxxxxxxxxxxx>]

Well,

I went over to the wrench today, where my car sat since tuesday night, and
they apparently got it running properly.  I started the car up, and it idled
well, and the throttle worked fine.  Here is what they said they did.

They replaced the Air Flow Sensor unit due to a flat spot. (bad trace or
something) $250
They used something called a Motor Vaccum?  that cleans out the injectors,
and the intake system.  They said the injectors were dirty.. Matched what
someone on the list said it might be.  Charged me $100 for that.
4.5 hours total labour $225
They also said they found a short in the wiring harness that had to do with
the O2 Sensor?  The fixed that, and disconnected the O2 sensor from the
system since it had a broken wire anyway.  I have a new one in the trunk,
and I have to get a new catalytic so I will have that installed when I get
the new cat installed.

Now I dont know if the problem is solved or if the car is in remission
again.  It went into remission like it has once before, however the car is
running well again.   I am going to go ahead and replace both temp sensors,
as well as the main relay.  I was also asked by Michael on one of the lists
I post to about the speed sensor near the transmission, and reference sensor
also near the transmission.  I may change those as well.  Further I am going
to clean all the contacts on the battery post with baking soda and a wire
brush to make sure they are clean.  I may also change the coil to something
with a hotter spark.

So that is it for now.  Can anyone explain how a bad Air flow sensor, and
dirty injectors, along with a short in the o2 sensor wiring  could cause
that problem?   The car idled bad during standing, but when you stepped on
the gas it would rev OK, but as soon as you put it under load it would lose
power unless you had your foot to the floor.  then the RPMS would jump but
as soon as the car started to move and the RPMS settled the car would almost
stall.   Exhaust would get really hot (unburnt fuel vapour out the pipes).

Also, has anyone heard of this motor vacuum thing before?  How does it work?

Thanks for all the help and pointers
Ron J
Toronto Canada

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