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Issue:
I've read at least 100 identical
situations from other forums of the very same problem and NOBODY has
ever found a solution to it.
Occurs when: Engine is at operating temperature.
Say I push the gas pedal to a couple of rpm (2500-4500) and I let
the engine come to idle, the revs will drop to about 400 and then
bounce to the normal ~650 and stay there.
Sometimes, the rpm will drop so much that the engine stalls. Now
this happens once a week and makes the problem spotting very
difficult.
I changed:
1. Spark plugs (OEM)
2. Fuel Filter (OEM)
3. Engine oil/filter
4. The whole engine (YES I have now fitted an almost new 2004 engine
in my car - DIY to follow)
5. Checked for vacuum leaks, air inlet hose.
6. Intake/Exhaust Camshaft
Sensors
7. MAF
8. Tried different fuel
stations, higher octane fuel (RON100)
The same problem occurred when I had the old engine as well. NO
Codes are stored and no engine lights comes on. Can't be VANOS since
it happened on both engines or any of the sensors.
I was ready to give up when a
fellow member (and BMW master technician @ UK) provided me the
following information:
Measure no. 4279488
M54 B22: Engine stalls when coasting
Release date 31/07/03 GB
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Vehicles affected E series E39 E46
Engine M54
Body CABRIO COMP COUPE LIM TOUR
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Complaint
The engine stalls when the vehicle is coasting, e.g. when
approaching traffic lights.
Vehicles concerned:
E39, E46 with M54/B22
Production period:
Start of series production to mid-April 2003
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Cause
Data status in the DME control unit.
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Measure
In the event of a customer complaint, reprogram the DME control unit
with DIS CD 35 or a more recent version. CD35 expected release is
early September 03.
The modified data status in the DME control unit was introduced into
production in calendar week 16/2003.
The symptoms match my case and
therefore I arranged a visit at the dealership. Two days later I got
my car back. Don't worry, the reprogramming doesn't take two days to
complete, just an hour. They just had my car sitting in their
garage. Can't do anything about it since there are the only ones on
the island who carry the BMW hardware.
Anyway, the car drove much
better after reprogramming. Much smoother specially while at
highway. When I release the gas pedal, I can see the rpm drop freely
until ~1100 and from there until idle (650) the ECU drops them
slowly slowly. Never had a stall again!! (knock on wood)
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