Help on peculiar warm-running problem

[timothylewis@xxxxxxxx]

Folks,
I am running an '82 528e, automatic, California Emissions, 161K miles.

THE PROBLEM:
Starts out searching for correct idle speed.  Begins around 1000 rpm,
works its way down to approx. 750 rpm.  On first acceleration (uphill)
the car hesitates strongly.  Punching it brings it along, but it seems
to oscillate lightly, as if I am applying and removing pedal pressure on
a frequency of approx. 1 second.  Also sounds like a diesel engine
(can't tell if it is knocking, pinging, or dieseling, nor do I know the
difference).  After the car is warm (a few minutes) all is well: good
acceleration, stable idle (in Drive; Park or Neutral still oscillates
around a 25 rpm range like it is searching for correct idle speed).  If
I stop the car (say, at a gas station), then restart, I will get the
same hesitation on first acceleration.  All is well afterwards.


OTHER OBSERVATIONS:
- --Checked Temperature Sensor, measured 1800 ohms at approx. 80-100
degress F.  Harness is cracked.
- --Thermo-time switch harness is cracked.
- --Fan-belt is incessantly noisy.  Belt dressing quiets it, but noise
returns quickly.
- --Disconnected Idle Speed Stabilizer; Idle went erratic.
- --Kick-down works fine.  Acceleration usually quite good.
- --Shifting is crisp.
- --Cylinders 3 and 4 have lower compression.  Probable valve guide oil
leaks.  [180   175   130   132   174   180]
- --Sounds like noisy injector in the area of 3 and 4.  Tried listening
with screwdriver, but could not get close enough.  Still, it definitely
did not have the valve's signature sound.  Much noiser than any of the
valves or other injectors.


RECENT WORK DONE:

- --Changed oil pan gasket (leaking)
- --Changed valve cover gasket (leaking)
- --new plugs (to replace "platinums' incorrrectly installed, gapped to
0.035)
- --Replaced O2 sensor (hunch)
- --replaced a number of atrophied hoses (i.e. PCV, etc.)
- --new motor mounts (junk yard, not exact same, but same critical
dimensions and form)
- --fixed a couple of vaccuum lines which had cracks

I hope this is useful and complete.  Let me know if more info is
needed.  I enjoy fixing these cars, and look forward to responses to
help me get on track.  Before I measured the Temp. Sensor, I was pretty
sure it had something to do with this...maybe telling the computer the
car was warmer than it was.  Doesn't seem to be the case though.  Thanks
for the help in advance, everyone.

Tim Lewis


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