BMW Fuel Injectors Theory, Operation, Diagnosis, and Recalls - Automotive Tech Info
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BMW Fuel Injectors
Theory, Operation, Diagnosis, and Recalls
By Dave Facciuto
Piezo injectors aren’t just for diesels.
Understanding new technology is
the key to successful repairs.
New decoupling rings must be installed each time
an injector is removed or replaced.
When we discuss BMW fuel based injector design that will First high pressure fuel enters
injectors we will focus primarily perform as well as the piezo the injector; all the pressure
on the direct injection type type, we will focus on the latter throughout the injector is equal
or GDI. Port injection has as these injectors are what you at this point. The piezo stack
been phased out and you will will encounter most often. is energized by the fuel control
mostly see the direct type unit and the injection event
injectors in the field. Direct According to Bosch, which takes place. Piezo injectors are
injection is not all that new. introduced piezo injectors to quieter and more precise than
the industry, a piezo actuator solenoid units, a huge benefit
BMW used direct injection acts up to five times faster than when microseconds count!
in airplane engines in the a standard injector solenoid
1930s. However they did not and the motion is frictionless. Some basics of piezo or
implement DI in automotive This translates into precise high voltage injectors:
applications until the mid 2000s. fuel metering and allows for
• The drivers in the
In 2007 BMW introduced the multiple injector events to
DME control both
N54 engine featuring direct occur each combustion cycle.
voltage and current.
injection and turbocharging
on the 335i model. A piezo element only expands • The driver will provide
a miniscule amount, so a boost voltage of
BMW’s current lineup features hundreds of slices are stacked up to 200 volts.
almost all turbocharged and on top of each other so that
direct injected engines. BMW • The driver will boost
the net movement is only
made the switch to direct current to around 10
about 0.004 inch. The actual
injection for good reason movement is microscopic, amps for a few hundred
— namely, improved fuel but enough to make the piezo microseconds.
efficiency, lower emissions, element act as the valve. • Voltage returns to
better performance, and cooler approximately 13.5 V
cylinder temperatures. Are they Since this movement is a and the holding current
bullet proof? Of course not . downward motion, a lever and drops to around 3 to 4
Yes Virginia, there is a recall. spring setup inside the injector amps for the remainder
But before we get into that, allows the pintle to open and of the injection event.
let’s delve into what makes the close. In a piezo injector, the
electronic engine management
modern BMW injector work.
system sends an electrical
Fuel system
Modern BMW signal to the valve, much like monitoring
the solenoid operated valve. But We won’t spend much time on
piezo injectors the unique property of a piezo the theory and operation of the
Although manufacturers such crystal, as mentioned before, GDI system and how it works
as Bosch, Siemens, and Delphi is that it changes shape when other than a bit of a refresher in
are all working on a solenoid exposed to electric current. regard to how the monitoring
system affects the injectors.
Previous articles have looked
in depth at the GDI system as
The inner workings of a piezo injector. a whole. The self-diagnosis
Note the stacked discs. system as it pertains to fuel
system monitoring, and
particularly fuel injectors,
can be broken down into:
• Lambda adaptation
• Trim control plausibility
monitoring
october 2020 21
BMW Fuel Injectors
• Diagnosis of injector aging pressure can be adjusted by • 30BA DME digital motor
• High pressure fuel the high pressure control. electronics, internal failure
control system If the rail pressure is too high, • 30BB DME digital motor
the result in the difference in electronics, internal failure
Diagnosis of injector aging is
simply a way of monitoring the two values is negative. If • Here are some of the
injector adaptation. A small the pressure is too low, then the affected models:
proportion of the short term fuel difference in the two values will • 2007-2013 BMW 135i (E82)
deviation is used for diagnostic result in a positive. If either of
these two values, negative or • 2007-2008 BMW 335i (E90)
injector aging and is stored as
an injector adaptation value in positive, exceeds a calibrated • 2007-2008 BMW 335xi (E91)
a separate map. The values of threshold for a certain amount • 2007-2010 BMW 335i (E92)
the separate map are renewed of time, a malfunction will be
detected with a fault set. The • 2007-2010 BMW 335i (E93)
every 497 miles. A fault will be
stored if the injector adaptation high pressure sensor signal is • 2009-2010 BMW 535i
exceeds a calibratable also monitored for plausibility & 535xi (E60)
minimum or maximum value. by using the lambda controller.
• 2009-2016 BMW Z4 35i (E89)
In the monitoring of the high If the adaptation shows rich
BMW models with MSD80 DME
pressure fuel control system you while the fuel pressure controller
software may set the fault codes
will be dealing with codes such is below a calibrated threshold,
30BA or 30BB. These fault codes
as p3282, p3284, p3003, and then a too high pressure signal
set when fuel injectors on bank 1
will be detected. The reverse will
p3090. The high pressure system or bank 2 develop circuit faults or
occur when a lean condition is
consists of a common fuel rail for when an injector MOSFET driver
detected and the fuel pressure
all high pressure piezo injection fails. Most times these fault
controller is above a calibrated
valves, a fuel rail pressure sensor, codes will be permanent and will
threshold. This will result in
a high pressure fuel pump with a not clear. However, be mindful
a too low pressure signal.
built in fuel volume control valve, there are situations where the
and an overpressure valve. fault codes will set intermittently.
Diagnosis
Based on the engine load and BMW models with turbocharged When diagnosing piezo fuel
speed, the high pressure needs N54 engines and MSD80 DME injector fault codes it is a good
to be adjusted to pressures set software can develop fuel injector idea to begin by checking fuel
forth in the map. To accomplish MOSFET driver failure. MOSFET injector voltage and current
this the pressure in the rail is stands for Metal–Oxide– using a lab scope. This will aid
measured and controlled with Semiconductor Field-Effect in determining whether the fault
the help of the fuel volume Transistor. It is a field-effect code is caused by the injector
control valve. Using the desired transistor where the voltage itself, the circuit, or the driver.
fuel mass and pressure preset determines the conductivity
value, a precontrol calculates of the device. It is used for Remember, piezo injectors
the driver signal as inputs for switching or amplifying signals, in normally operate at extremely
the fuel volume control valve. this case switching the injector. high voltages, so use extreme
care when working around
In diagnosis, the high pressure The ability to change conductivity connections. Do not touch any
monitoring system analyzes with the amount of applied of the injector terminals while
the difference between the voltage can be used for amplifying the engine is running. Set your
measured fuel pressure and the or switching electronic signals. scope to display voltage and
set point pressure. Your scan This driver failure will cause current at the same time. Set the
tool often has PIDs that display an injector to stop delivering voltage range to -200 volts DC
requested fuel pressure and fuel and an engine misfire to to +200 volts DC. Current range
actual pressure. The monitor occur. The Check Engine light should be set around 10 amps.
determines whether or not the will be ON with these related Beginning on a cylinder with no
set point value of the fuel rail fault codes (error messages): faults, establish a possible known
22 the bimmer pub
pattern isn’t right In checking your wiring integrity
you most likely you will want to perform a
have a faulty voltage drop test of the wiring
injector or driver. under load. This is a bit tricky
Most times when in that, due to the high voltages
the DME is at the engine management applies,
you can’t energize the circuit
fault, the current
just by powering it up. You will
pattern will try
have to supply your own load.
to climb, but fail. First disconnect the negative
The MOSFET battery terminal, then locate
Your lab scope should graph both the current drivers fail when the DME and disconnect both
ramp on and off plus the voltage patterns. the attempt DME connectors. Consult an
(Courtesy Opus IVS™) to charge the accurate wiring diagram and
injector begins. use your ohmmeter to verify
good pattern. Insert a back probe
that you are on the correct wire
into the white wire, then attach In the event you feel as though from the DME to the injector.
your current probe around the you have a faulty injector or
same wire. Be sure to consult the driver, turn off the engine, Now that you have identified the
wiring diagram for the specific remove your test equipment correct wire, connect the injector
model you are working on. and disconnect all the injectors. side of the wiring harness to
battery negative. Then, at the
Voltage should range from 0 to Connect your scan tool, either
DME side, connect a test light
almost 160 volts DC. The current ISTA-D or a factory compatible
(the load) to the injector terminal
pattern will peak at around scan tool, and try to clear the
to be tested, then connect it to
8 amps when the injector is codes. If the codes will not clear battery positive. You can use
switched on, then the current will you most likely have a DME fault the jump start terminal if you
drop while the injector is open, or wiring issue. If the fault clears wish, and the test light should
and, finally reverse when the then most likely the injector is illuminate. Use your voltmeter
injector is switched off. Current faulty. Double check this as now and check the voltage at
reverses because the piezo these babies are expensive! the DME connection and you
element acts as a capacitor,
and when switched off,
the voltage travels back
through the injector. If the
In the case of this 535 model the injector wires are white.
october 2020 23
BMW Fuel Injectors
should have 0.2 V
or less. Check the
integrity of all your
suspect circuits
including both legs
of each injector.
If the fault code
does not clear
even when You should have 0.2 V or less
disconnecting all when checking the voltage
the injectors, and if drop of the injector circuit.
the injector wiring (Courtesy Opus IVS™) This removal and installation tool is needed for the
tests OK, the issue N55 engine. With N54 engines you can use the slide
has been isolated
to the DME. There
hammer type puller.
is a method for opening the
DME and checking the MOSFET; injectors may cause misfire faults to replace ALL fuel injectors
however there are no serviceable with erratic engine operation. depending on which injectors are
parts internally so a new unit already installed on their BMW.
Your customer may be entitled
from BMW is the answer. to repair from the BMW dealer.
To check for recalls go to:
What do all those
We have covered a possible
electrical failure of the injectors www.bmwusa.com/safety- numbers mean?
and drivers, but what about a and-emission-recalls.html Here is a typical FI part number:
mechanical failure? A common 13537585261-12. The following
Also, BMW has issued extended is how the part number will read
symptom of a mechanical failure
warranties on injectors for certain on the actual fuel injector. Here
is a misfire coupled with: black
models according to TIS bulletin is the breakdown: BMW Part
smoke from the tailpipe; rich
SI B01 05 18. N63T ENGINE Number -13537585261 Fuel
smelling exhaust; engine oil
FUEL INJECTORS: LIMITED Injector Index: 12. BMW only
dilution; and even engine hydro
WARRANTY EXTENSION TO manufactures injectors with
lock. You may have misfire codes
and rich fuel trims alerting you 10 YEARS/120,000 MILES. an index of 11 or higher. There
to the problem. What typically TIS bulletin SI B01 02 15 has are two points to remember:
happens is the injector doesn’t also extended the warranty
1. Direct injection fuel injectors
completely shut and drips on N54 Engine Fuel Injectors
must use a new decoupling
excess fuel into the cylinders. – Limited Warranty Extension
ring (13537564751) and a
This is why it is imperative to 10 Years/120,000 Miles.
new seal (13537584315)
to not let these symptoms when removed or replaced.
New injectors have been
continue in your customer’s These part numbers may
released from BMW for the N63,
vehicle, and to repair the vary depending on the fuel
N74, and N54 with “improved
condition as soon as possible. injector part number. New
internal filtering” and “special
thermo compensating oil.” injectors will come with a seal
Recalls and Unfortunately the new injectors installed, otherwise you will
warranties have calibration and construction need a special tool to expand
the seal when installing
BMW has issued a recall on differences that prevent them
certain models. This emissions from being intermixed with older and compress it again.
recall involves E60, E61, E71, style injectors “index 10,” but 2. Fuel injectors with an index of
E82, E88, E90, E92, and E93 they can be intermixed with 10 or lower cannot be paired
vehicles with N54 engines which newer “index 11” injectors. with injectors that have an
were produced from 04/02/2007 So in some cases of injector index of 11 or higher. They
through 11/30/2008. The piezo failure, BMW owners might have are calibrated differently and
24 the bimmer pub
AUTOMOTIVE
TEC H
each installed injector are stored
in the DME control module. The
calibration values are allocated to
the individual cylinders according
AutomotiveTechInfo.com
to the installation of the injectors.
The injection volumes calculated
Be sure the latest index by the DME control module are
corrected by these calibration
markings are on the injectors
values, thus improving the
you are replacing exhaust emissions. Using ISTA-P
(BMW TSB SI B13 14 10). or compatible scan tool these
values can be changed or new
Calibration values entered. The calibration
numbers values are printed in two blocks
marked on each with three digits on each
the injectors injector. The inscription can be
located either on the plastic
bracket or on the metallic upper
part. If injectors are renewed or
replaced, it must be assured that
the printed calibration values of
each injector are assigned to the
the newer injectors (index correct cylinder in the DME.
11 and up) are made as a
replacement for the faulty/ The menu on your scan tool
defective injectors (index 10 will read something like this:
and lower). This means that • Vehicle identification
if the customer is replacing • Function selection Log on for free access to
some injectors, but not all,
you must check the index on • Select “Service functions” 1600+ technical articles!
the remaining injectors and • Select “Engine electronics”
to see if any of them have
• Select “Adjustment functions”
an index of less than 11. If
so, those injectors will have • Select “Adjust injectors”
to be replaced at the same • Injection quantity
time to prevent driveability compensation
issues and possible
catastrophic engine damage. For each replaced injector,
the adjustment value must
In the end, all of the fuel injectors be entered according to
on a particular engine must have the installation location.
an index of 11 or higher. Most
shops agree you should go with As these vehicles get more
all new injectors index 12 and not mileage on them, you are
have any issues in the future. bound to see more fuel injector
failures. Providing accurate
Calibration diagnosis coupled with the
During vehicle assembly, after latest parts updates will ensure
installation of the DME control your customers of a quality
module, the calibration values of repair and peace of mind. •
october 2020 25You can also read
