Reliability and Maintenance
We cannot stress enough that performing regular service on your N54-powered BMW is imperative. We’ve outlined the weak points for you and how to fix them so you can ensure your 335i is ready to handle more power reliably.
Regular oil changes with BMW-approved oil, like LIQUI MOLY
Regular replacement of spark plugs, especially if you are running a performance tune.
Walnut Shell Blasting is critical to remove carbon buildup from the intake valves and ports (every 30k miles)
Other than the walnut blasting, this list could describe maintenance for any vehicle. Add in brakes, air filters, oil filters, and fuel filters, and your 335i should be fine. |
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Common Problems
Water Pump/Thermostat:
The N54 uses an electrically driven water pump. The benefit is that there is less parasitic loss to engine power since no belt drives the pump from the rotation of the crankshaft. The downside is that if your pump fails, which they are known to do every 60k miles or so, your BMW will enter limp mode and throw a check engine light. It is important to replace the water pump on schedule, along with the thermostat, to ensure you aren’t stranded by a fault that is easily fixed. We also recommend you service your 335i with OEM BMW parts for the best results. |
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High-Pressure Fuel Pump (HPFP):
Another electrically driven pump that causes some mild frustration with BMW owners is the HPFP, which can fail in a similar fashion to the water pump and also cause a limp mode as well as starting issues. In older N54-powered BMWs, the HPFP was not originally up to the task of supplying fuel consistently over the life of the vehicle and became a regular failure point. BMW has since updated their HPFP with a unit that is much more reliable and should be one of the first things you replace if your pump has not already been updated. Once again, the OEM BMW fuel pump is your best bet. You can also upgrade to a Low-Pressure Fuel Pump setup for greater reliability. |
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Oil Filter Housing Gasket/Oil Cooler Gasket:
These common spots for oil leaks are easily fixed. If you notice oil consumption issues or see spots on your garage floor, chances are, one or both of these gaskets is the culprit. Replace both gaskets when you purchase your car or notice the leak and you’ll be fine. |
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Charge Pipe:
BMW, like many manufacturers, used plastic piping for their charge air delivery to the throttle body. This saves on cost but skimps on reliability. Over time, the charge pipe becomes brittle and can crack, which causes a boost leak and introduces air not measured by the MAF, which will cause your car to run poorly since it won’t know how much fuel to supply for a correct mixture. In this case, we suggest upgrading your charge pipes along with an aftermarket intercooler for better performance and longevity. There are tons of BMW 335i intercooler options we have available and all are great choices. Select the one you like best and you can’t go wrong. |
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Walnut Shell Blasting:
We mentioned this above in the basic maintenance section, but thought it would be a good idea to include it here as well since the carbon buildup that happens can be considered a fault with the Direct Injection system. This is another involved DIY, but one that has been well documented. With a media blaster tank and proper fittings, you can easily clean your ports and valves at home roughly every two years. To maintain your N54, this service is critical. |
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Wastegate Rattle:
The N54 wastegates notoriously rattle, even when they are functioning properly. In early engines, however, there were issues with the wastegates that caused them to fail. They would rattle noticeably more before failing completely. Replace your wastegates if the issue has not been addressed on your 335i with updated OEM BMW wastegates and never worry about it again. |
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Upgrades
Some of these reliability issues can be mitigated with upgrades as we mentioned above. The best upgrades to your N54 for power and performance include parts you likely know and love. |
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Turbo Kits
By upgrading your turbo setup, you can both add impressive power figures as well as completely remedy the wastegate issue. Vargas Turbo Technologies has direct OEM replacements and wastegate rattle repair kits as well as some of the most respected turbocharger upgrades on the market. Their Game Changer series of turbochargers have become popular for their reliability, build quality, and incredible ability to support up to 750hp. |
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Software
By upgrading your turbo setup, you can both add impressive power figures as well as completely remedy the wastegate issue. Vargas Turbo Technologies has direct OEM replacements and wastegate rattle repair kits as well as some of the most respected turbocharger upgrades on the market. Their Game Changer series of turbochargers have become popular for their reliability, build quality, and incredible ability to support up to 750hp. |
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Intake
The Turner Motorsport Turbo-Side Intakes are perfect for cleaning up your engine bay as well as increasing the airflow to your engine to support more power. These are designed to eliminate restrictions, decrease intake air temperatures, and increase the air volume and can be your first modification or a final touch on your build for a clean, yet functional, upgrade under the hood. |
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Downpipes
Turner Motorsport high-flow catted downpipes add roughly 36hp and are a key piece to the puzzle of improved performance from your N54. Paired with the turbo-side intakes, JB4 software, upgraded turbochargers, and a full exhaust, these downpipes help bring your N54-powered 335i into a new class. |
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Exhaust
Lastly, our full exhaust system is designed to offer you better performance without compromising the comfort of your daily driven 335i. Our valved system allows you to determine how much volume you want. when you require discretion, simply close the valves and enjoy a milder exhaust note until you're ready to unleash the full sound of your N54. |
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