22 BMWcar
BUYING GUIDE
common, too, as are issues with ignition
coils. There’s also an electric water pump
which commonly causes expensive trouble.
Overall, this engine probably features a
more complex array of ancillary items than
the M57 so, arguably, the potential for
trouble is greater. However, don’t conclude
from this that the N52 is an irritatingly
troublesome engine, because it’s not.
“One central issue that doesn’t help with
the long-term health of these engines is the
fact that BMW was pretty optimistic with
the service life predictions made for various
components,” Andy told me. “For example,
the official maintenance schedule calls for a
new set of spark plugs every 70,000 miles,
which is simply ludicrous. This fact alone
has probably given rise to the increased
rate of ignition coil failures typically seen
on this engine. Struggling spark plugs place
a greater and unnecessary loading on the
coils which, unsurprisingly, can’t cope.”
RUNNING ISSUES
“Replacement coils aren’t terribly expensive,
at £58 each, but that’s not really the point.
The official, BMW workshop approach is to
replace all six if one fails, which certainly
balloons the bill. Then, if they choose to
fit a new set of spark plugs as well, that’ll
add £126 to the total. If whatever misfire
or starting issue isn’t cured by doing this,
they’ll then start investigating fuel injectors
(£259 each) and, if that doesn’t do the
trick, attention will turn to the high-pressure
fuel pump, which costs £809 to replace.”
The fact that this engine was among the
first generation of units operating a high-
pressure fuel system is perhaps one of
the reasons why fuel- and running-related
issues are being seen today. Having said
that, maintenance and servicing are key
factors, too. Andy’s advice is that spark plugs
should be changed every 35,000 miles, to
reduce the loading on the coils. The engine
management system is very sensitive to330i 330d
CAPACITY (CC/CYL) 2,996/6 2,993/6
POWER (HP) 258 @ 6,660 231 @ 4,000
TORQUE (LB FT) 221 @ 2,500-4,000 369 @ 1,750-3,000
0-60MPH 6.1 6.6
TOP SPEED 155 150
ECONOMY (MPG) 32.5 39.2
KERB WEIGHT (KG) 1,525 1,710E90 330i/330d tech specs