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
Figure 2a, Mercedes 722.6 Transmissions
Figure 2b, Mercedes 722.6 Transmissions
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
The conductor plate coupler provides the
connection to the wiring harness for the
transmission control module. See figure 2b, black
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
Figure 3a, BMW E46 3-series model Fuel Levels.
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.
Figure 4a, Mercedes motor mounts.
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.
Figure 5a, BMW E39 and E46 air filter.
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.
Figure 6a, Porsche 993/911air filter.
The air filter on the in Figure 6a is
an air filter from 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
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.
Figure 7a, Mini Cooper convertible top side rail mechanism.
Figure 7a is a right side
convertible top rail mechanism
from a 2005 Mini Cooper
The area circled in red are broken
parts where the cable anchors to
the mechanism. Over time the
connection fatigues and fails. The
result is non-release of the
convertible top on the side that the
Figure 7, Mini Cooper oil filter housing cap.
The Mini Cooper oil filter cap on the right in
Figure 7 is missing it's plastic cage. The
plastic cage inserts into the oil filter, and
can sometimes be pulled out with the filter.
If care is not taken by the technician, the
plastic cage can easily get discarded with
the old oil filter.
The oil filter cap on the left is a new cap
complete with the plastic cage.
Without the plastic cage in place, the
spring in the cap will tear through the end
of the oil filter, and possibly cause a
change in oil pressure as a result.
The Porsche 928 in Figure 8 was subjected to
incompetent past electrical repairs. With older
automobiles, electrical wiring problems are common.
Typically, older automobiles have had a few owners,
and somewhere in the history of the automobile an
owner will add electronic accessories. More often
than not, the electronic accessory will appear to be
nicely installed from the outside. "Behind the scenes,"
it is common to find poorly connected wires,
unorganized wires that look like a bunch of spaghetti,
and accessories being powered by incorrect
systems (i.e. tapping into the power for the ESP
system, or ABS system for example).
Tapping into certain systems to power up an
electronic accessory can result in falsely activated
dash warning MILs, and/or damaged control modules.
Professional technicians agree that aftermarket
accessories should not be installed on any high-end
Figure 8, wiring harness damage from past incompetent work.
Long oil change intervals is a
major cause of sludge build-up in
engines. Figure 9a shows the
sludge build-up and discoloration
in the cylinder head and inside the
valve cover. The vehicle in the
photo is a 1999 BMW 323i with
Sludge inside the engine restricts
oil flow, and causes accelerated
wear of internal engine
In some areas of this cylinder
head, the sludge was 1/2" thick!
Figure 9a, Sludge build-up from long oil change intervals.
Figure 9b is a detailed view of the
same engine shown in Figure 9a.
If the owner were servicing this
vehicle with engine oil and filter
changes every 5000 miles or less
with good quality oil, the internal
parts of the engine would be
bright aluminum with no sludge
Figure 9b, Sludge build-up from long oil change intervals.
Figure 10, Separated engine oil filter.
Figure 10 shows a separated oil filter. This oil filter was found on
the same BMW engine shown above in figures 9a and 9b.
A combination of a low quality oil filter, and long oil change intervals
has caused this filter to break apart. Smaller pieces of the filter are
likely scattered throughout the engine, which can cause a restriction
in the oil galleries.
Figure 10a shows the difference between a proper factory
Mercedes fleece oil filter (far right), and cheap aftermarket oil filters
(the two filters to the left) that are collapsed from oil pressure. If you
look closely, the far left filter has the plastic end cap missing - it was
stuck in the oil filter housing cap. The collapsed filters were starving
the engine of oil, subjecting the engine to added wear, and
shortening the engine lifespan.
Figure 9c, Sludge build-up from long oil change intervals.
Figure 9c shows the sludge build
up in the engine oil pan of a 1999
The sludge is the result of a
combination of long engine oil
change intervals, poor quality oil,
and lack of other maintenance.
Figure 11a shows a replacement telescopic water pipe that takes
the place of the leak-prone one piece water pipe (Figure 11b).
The telescopic water pipe saves about half of the labor time (huge
savings over the BMW dealer labor) compared to replacing the
water pipe with the same one piece pipe, which requires
dismantling most of the engine.
The telescopic pipe expands in place to avoid the removal of the
front of the engine - significant savings in labor time.
BMW dealers charge up to $10,000 for the replacement of the one
piece pipe. We can install the telescopic pipe for $4000 including
replacement of the water pump
Figure 11a, E65 745i new/improved valley water pipe.
Figure 1, BMW E46 Ignition Coils
Figure 12, Mercedes 202 Burnt S.A.M. Circuit Board.
Figure 12 shows a burnt circuit board on a Mercedes front
S.A.M. (Signal Acquisition/Activation Module).
The customer explained to us that the windshield wiper stopped
in the middle of the windshield while driving in wet weather. She
took the car to a non-Mercedes service center for repairs. The
service center supposedly replaced the wiper motor. None of the
related fasteners appear to have been tampered with, so it's
questionable if the wiper motor was even replaced. Their
technician tested the wiper with a water hose running down the
windshield. In the process, water managed to get inside the front
fuse box, and inside the S.A.M., causing the circuit board to short
Since the service center was not a Mercedes specialist, they told
the customer that they couldn't perform the S.A.M. replacement (a
Mercedes SDS diagnostic system is needed for this type of
repair). Basically, they damaged the customer's car, and told the
customer that they couldn't repair the problem they caused. The
customer brought the vehicle to us for repairs (we have the
required SDS diagnostic system - see our Equipment page). We
replaced and programmed the S.A.M. and the fuse box, and
lubricated the wiper arm linkage. The wiper now functions
Lesson learned: Do not let service centers touch your car if they
do not have the proper factory equipment. If a service center
claims that they service Mercedes, but do not have the factory
equipment, then they are not a Mercedes specialist.
Figure 11b, E65 745i leaking one piece valley water pipe.
Figure 10a, Separated engine oil filter.
Figure 10b, Separated engine oil filter.
Figure 10b shows an aftermarket oil filter that was in the process of
collapsing in on itself. As a result. the engine was starving of oil.
Figure 13, Porsche 99-09 Alternator Pulley (with Free Wheel Lock) .
Figure 13 shows a 99-09 Porsche alternator pulley with the free
wheel lock feature. The pulley locks and spins the alternator
under acceleration, and free wheels under braking, and coasting.
When the free wheel lock mechanism wears, the pulley will rattle
(heard best at idle). In some cases, the locking mechanism can
fail, causing the alternator to spin at reduced rpm or not spin at all.
This condition can lead to an under charged battery or dead
Figure 14, BMW X5 Door Handle Carrier.
Figure 14 shows a broken hinge on a BMW X5 door handle
carrier (circled in red). When the hinge breaks, in most cases the
outside door handle will not open the door that is afflicted.
Replacement of the door handle carrier is pretty involved due to
the tight confines that the part resides in, and also the number of
small parts that must simultaneously fit together upon reassembly.
Replacement of this part is not recommended to be performed by
the vehicle owner.
Figure 15, BMW E38 Ignition Lock.
Figure 15 shows a broken ignition lock from a 1998 BMW 740iL.
When the ignition lock breaks, it often causes the ignition tumbler
to spin around 360 degrees, making it difficult to shut the engine
off. The ignition lock is tricky to access and remove due to the
theft-deterrant bolts that anchor the lock in place - definitely not a
DIY home project.
Figure 16, Porsche 997 Turbo Heat Exchanger.
Figure 16 shows a leaking heat exchanger (the pink residue is
dried Porsche antifreeze) from a 2007 Porsche 997 Turbo. This is
one of two heat exchangers that reside on top of the engine.
Access to these heat exchangers are very tight, and requires
removal of the oil filter housing, removal of the throttle body and
cross over tube, and often lowering of the engine itself
depending on which of the two heat exchangers needs to be
Figure 17b, BMW E90 2006+ 3 series water pump.
Figure 17a, BMW E90 2006+ 3 series coolant thermostat.
Figure 17b shows a faulty water pump off of a 2006 BMW 3
series E90. These water pumps are electrically operated. Over
time, these electric water pumps lose performance and slow
down over time, causing the engine to run hotter and hotter.
Figure 17a shows a faulty coolant thermostat off of a 2006 BMW
3 series E90. These thermostats are electronic operated. Over
time, these electronic thermostats malfunction over time (usuallt
stick open), causing the engine to run cooler than it should, using
more fuel, higher emissions, and typically activating a Service
Engine Soon warning on the instrument cluster.
Figure 18, Mercedes Brake Switch.
Figure 18 shows a faulty Mercedes brake switch. Faulty brake
switches can cause check engine/service engine soon
warnings, ABS, ESP, BAS, and transmission performance
Figure 19, Porsche Oil Separator / Crankcase Vent Valve.
Figure 19 shows a faulty/leaking Porsche oil
separator/crankcase vent valve. In addition to oil leaking out of the
vent valve, creating an oil mess down the face of the engine, odd
noises and possibly a check engine warning can occur.
Figure 20, Porsche 911/997 Twin Turbo Water Manifold.
Figure 20 shows a faulty/broken Porsche 911/997 Twin Turbo
water manifold. The pressed-in hose fitting separated from the
water manifold casting. The red arrow illustrates the location
where the hose fitting would anchor into the casting.
Due to the tight confines of the location where the water manifold
resides, it can take approximately 24 hours from start to finish to
replace this part. Ordering this part takes some caution as well,
because it is often confused with the GT3 water manifold which
has an absence of the fitting above the one that separated here.