East West European Imports - BMW Mercedes Porsche Ferrari

Figure 1, BMW E46 Ignition Coils

BMW ignition coils do go faulty from time to time. The ignition coils shown in figure 1 were from a 1999 BMW 323i.
The vehicle came to us with a Check Engine MIL on. The technician noticed that there were ignition misfires present.
Running module scan with our BMW GT1 diagnostic system confirmed the technician's thoughts. The GT1 revealed
that number 4 cylinder was misfiring.

The technician removed the number 4 ignition coil to inspect for any irregularities. The spark plug was properly
torqued, but the ignition coil itself had signs of arcing, and the plastic housing was melted as well. See figure 1, red
circles. With this discovery, the technician decided to remove all of the ignition coils for inspection. Sure enough, all
of the ignition coils were suffering from the same affliction.

This vehicle also had fault codes for oxygen sensors. The technician recommended to the customer that the four
oxygen sensors, six ignition coils, six spark plugs, and the fuel filter to be replaced. Also recommended was
updating of the DME with the latest software version. The customer authorized the repairs. After the repairs were
completed, engine performance was smooth and powerful, and no fault codes returned.

Mercedes 722.6 transmissions are pretty durable
mechanically. However, the Achilles heal of the
722.6 is the conductor plate coupler. See figure
2a, red circle, shown disconnected from the
transmission.

The conductor plate coupler provides the
connection to the wiring harness for the
transmission control module. See figure 2b, black
box.

The issue with the conductor plate coupler is that
it is prone to leaking. The transmission fluid leaks
into the coupler, and creates electrical shorts.
This situation can cause a check engine MIL,
irregular shifting, limp mode, or damage to the
transmission control module.

In some cases, the transmission fluid can leak all
the way up to the transmission control module,
through approximately 3 feet of wiring. See figure
2b, red circle, transmission fluid leakage.

As is the case with many european automobiles,
Mercedes have very sensitive electronics.
Electrical shorts or spikes can "zap" out a control
module in no time. Even though fuses are in place
to protect the electrical components, they don't
always react quick enough. Its common to find a
"zapped" out module and all fuses in perfect
condition.

The BMW E46 3-series model uses two separate
fuel tanks. The fuel system uses a jet system to
transfer fuel from the left tank to the right tank.
When fuel level irregularities come about, Our
BMW technician can access the amount of fuel in
each tank via instrument cluster. See the
red-circled area in Figure 3a. The first three digits
(015) is the amount of fuel in liters in the left tank.
The last three digits (327) is the amount of fuel in
liters in the right tank. 1.5 liters + 32.7 liters = 34.2
liters. The fuel capacity for the E46 model is 63
liters, 34.2 liters is equal to slightly more than 1/2
the fuel capacity. Notice the fuel gauge in Figure
3a; the needle is slightly past the half mark, so this
fuel gauge is reading accurately.

Mercedes motor mounts are
filled with very thick oil. The oil
dampens the vibrations from
the engine. Over time, the
rubber bladder containing the
oil can stretch or crack,
allowing the oil to spread out
or leak. The result is a
"sunken" motor mount. See the
red height reference lines in
Figure 4a. The motor mount on
the right is an old sunken
mount, and the one on the
right is a new updated style
motor mount (both mounts are
for the same vehicle).

Sunken motor mounts cause
the engine to sink in the engine
bay. This situation changes
the geometry of the driveline.
The result is added strain on
the transmission, engine
wiring harness, and hoses.
also, vibrations from the
engine transmit into the
chassis, which can fatigue
and loosen fasteners.

There are two separate air filter
designs for the BMW E39 and E46
chassis 6 cylinder engines.
Figure 5a displays the two
different designs. The air filter on
the left is a "light duty" filter. The
air filter on the right is a "heavy
duty" filter with a layer of black
foam attached to the underside.

To avoid potential MIL (Mafunction
Indicator Lamp) warnings, we
prefer to install the heavy duty
filters on the 6 cylinder E39 and
E46 chassis cars.

Under certain circumstances, the
light duty filter can have a
negative affect on the air/fuel
mixture. The mass air flow sensor
can compensate for the less
restrictive filter, but this shifts the
calibration closer to the limits of its
operation perameters, making it
easier for MIL warnings to pop up
on the instrument cluster.

The air filter on the left in Figure
6a is an air filter form a 1995
Porsche 993/911. The filter was
not replaced for quite some time,
resulting in an extremely restricted
filter. In fact, this filter was
partially "sucked" into the airbox
by the choking engine!

The air filter on the right is the
same filter (albeit new). Notice the
white base flanges compared to
the distorted flanges on the old
filter.

We recommend replacement of
engine air filter(s) on all
automobiles at no more than
30,000 mile intervals (or cleaning
and oiling if its a K&N filter).

Dirty air filters rob your engine of
performance and fuel economy,
so keep track of the condition of
your air filters.