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- Number 1 -
—— what fault codes do you have stored in the DME before trying to perform a active test on the injectors.
- number 2 -
—— what drivability issues are you having? Do you have a dead misfire? Or a intermittent misfire? Also, the DME is programmed in its logic, to turn the fuel injector off, if there is a “misfire - damaging catalyst” fault code stored. This logic is very smart because it prevents that cylinder from being washed down with raw fuel that is not being ignited by the spark plug. This try’s to prevent damage to the piston / rings / and for the immediate - the catalytic converters. That raw fuel dumping into the catalytic converters is like dumping gasoline on a wood fire. It makes the catalyst become basically a blow torch and it will damage the catalytic converters in short time if that feature was not programmed into the DME.
- number 3 -
—— record and erase all engine DME fault codes, cycle the key, and start the car back up and try to do a KOEO active test on injector number one and see if you are getting a difference in the engine running like you are experiencing with the other cylinders.
- number 4 -
—— disconnect the number one injector harness connector, using a volt meter (DVOM if avail), probe the signal pin at the connector while it is unplugged, and ground the other volt meter lead to ground. Try activating number one injector again, engine running - or not running, and see if your getting a actual command from the ECU to actuate that injector. Wiggle / slightly tug on the wires in the harness related to the number one injector and see if you can see changing values on the voltmeter. IMPORTANT!! these piezo injectors operate at a HIGH VOLTAGE! set your volt meter or lab scope to -200 to +200 DC, the CURRENT range is about 10amps. don’t blow your meter up! don’t short the pins out either! Be very careful.
— I copied this from the BMW injector theory of operation bulletin -
- BMW models with turbocharged N54 engines and MSD80 DME software can develop fuel injector MOSFET driver failure. MOSFET stands for Metal–Oxide– Semiconductor Field-Effect Transistor. It is a field-effect transistor where the voltage determines the conductivity
of the device. It is used for switching or amplifying signals, in this case switching the injector.
The ability to change conductivity with the amount of applied voltage can be used for amplifying or switching electronic signals. This driver failure will cause
an injector to stop delivering fuel and an engine misfire to occur. The Check Engine light will be ON with these related fault codes (error messages):
• 30BA DME digital motor electronics, internal failure
• 30BB DME digital motor electronics, internal failure
• Here are some of the affected models:
• 2007-2013 BMW 135i (E82) • 2007-2008 BMW 335i (E90) • 2007-2008 BMW 335xi (E91) • 2007-2010 BMW 335i (E92) • 2007-2010 BMW 335i (E93) • 2009-2010 BMW 535i
& 535xi (E60)
• 2009-2016 BMW Z4 35i (E89)
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