...
There’s nothing better than adding some more power to your car; whether it’s bolting on some new downpipes, crimping some wires, or something as simple as plugging in the COBB AccessPORT to your OBDII port. The N54 powered BMWs respond amazingly well to tuning, but the increased power has caused some owners to experience misfire issues. Trouble shooting Troubleshooting and repairing a BMW can seem like a daunting task with things like an advanced electrical system, specialized tools, and intimidating engine covers. But, diagnosing and repairing the typical misfire is fairly straight forward, and we will show you how!
...
The N54 motor is BMW’s first shot at a turbo charged turbocharged gasoline direct injection engine. A direct injection motor injects gasoline directly in to into the engine cylinder where as whereas a traditional fuel-injected motor injects gasoline in to into the intake tract or cylinder port. Because gasoline is injected directly in to into the cylinder, BMW has designed a specific spark plug to sit at a specific location relative to the injector to ensure proper ignition. The ECU creates this ignition by telling the coil pack when to deliver the high voltage charge to the spark plug. This design combined with BMW’s advanced ECU logic allows the car to precisely control fuel and spark in order to not only increase performance , but fuel mileage as well.
...
As many owners have found, this incredible power has come with a few downsides. The now infamous high-pressure fuel pump and injector recalls have caused multiple N54 owners check-engine-light anxiety. The BMW Maintenance Schedule calls for the spark plugs to be replaced every 45,000 miles, but our experience shows that this maintenance interval should probably be closer to 25,000 miles. We have also seen the other part of this spark equation, the coil packs, fail on cars with low miles. So, in short, our internal testing and experience has shown that the ignition system requires more stringent maintenance in general, but especially on a modified car.
...
In the very beginning stages of this inevitable issue, indications will only show themselves when the car is pushed hard due to tuning combined with more aggressive driving. In many cases, the misfires caused by the combination of tuning, bolt-on parts, and aggressive driving style will throw check engine codes, however, under some loads, the misfire may only be felt by the driver without a resulting trouble code. The intricate BMW ECU logic is able to measure the variance in the expected acceleration of the crank to determine if the car is misfiring. When the coil pack is trying to create the spark, it is fighting against pressure in the cylinder and spark plug condition. Cylinder pressure is closely related to engine torque, so when torque is increased at higher RPM, the coil pack must recharge between sparks more quickly while still providing ample voltage to the plug. If the plug is worn out, it requires a higher voltage to jump the gap and could cause a misfire. If the coil pack is worn, it would not be able to recharge quickly enough to provide the required voltage to the plug. Therefore, this is why many users only see misfire codes with a tuned car and not on stock mapping. As the coils and plugs continue to degrade, even the stock mapping will have misfire issues.
...