What is the BMW B58?
BMW’s B58 engine is a 3.0L inline-6 turbocharged, direct injection gasoline engine produced from 2016-present. As with the N55, the B58 engine uses a single twin-scroll turbocharger. Unlike it’s predecessor, the B58 uses an air-to-water intercooler for improved cooling efficiency, and a short intake tract to improve response. So far, the B58 won four Ward’s 10 Best Engine awards.
What BMW’s use the B58 Engine?
The BMW B58 engine is found in the following models:
- 2016-2019 M140i
- 2016-present M240i
- 2016-present 340i
- 2019-present M340i
- 2016-present 440i
- 2020-present M440i
- 2020-present M440i
- 2017-present 540i
- 2017-present 640i
- 2016-2019 740i / 740Li
- 2020-present 740i
- 2020-present 840i
- 2017-present X3 M40i
- 2017-present X4 M40i
- 2018-present X5 40i
- 2020-present X6 40i
- 2018-present X7 40i
- 2018-present Z4 M40i
What Are the Common B58 Standard Maintenance Items?
A few common B58 standard maintenance items include:
- Fluids (oil & coolant)
- Spark plugs & ignition coils
- Walnut blasting (intake valve cleaning)
What is B58 Walnut Blasting?
Ahhh…walnut blasting. As avid N54 enthusiasts this is one of our favorite topics. Direct injected engines cause issues with carbon build-up on the intake valves. Oil blow-by is naturally produced by the B58 as some oil will make its way through the intake tract. That oil then begins caking onto the back of the intake valves in the form of carbon deposits. This of course restricts airflow into the engine. It’s simply due to the nature of direct injected engines. Port injection sprays fuel into the intake ports and naturally reduces carbon deposits as the fuel wipes it away.
Now, there is good news. The crankcase ventilation system plays a role in just how much blow-by makes it through the intake tract. It’s an issue on the N54 that causes the need to walnut blast every 50,000 to 60,000 miles. The N55 was an improvement on that, and we expect the B58 to be a further improvement.
Is Walnut Blasting Needed for the B58?
Probably. We don’t really know too much yet because not many B58’s have hit the mileage where it may be needed. As we discussed briefly above, the N55 was an improvement over the N54. The N55 only requires walnut blasting every 80,000’ish miles. Even then, it’s not truly needed. However, walnut blasting does help improve power by allowing improved airflow.
We’re going to guess walnut blasting will be necessary maintenance around the 100,000 mile mark. You can likely stretch that further. However, time will tell just how bad the valves look around the 100,000+ mile mark.
Why is My B58 Idling Rough?
Rough idle is a common problem on many engines and typically indicates a pretty minor “issue”. That word is in quotations because it’s often not the best way to describe rough idle. Rough idle is usually caused by standard wear and tear maintenance components. If your B58 is idling rough then consider the following:
- Spark plugs
- Ignition coils
- VANOS solenoids
- Dirty intake valves (walnut blast needed)
With the current age of the B58 you’ll likely find the rough idle is caused by old, worn spark plugs or ignition coils. We suspect VANOS solenoids will start needing replacement north of 100,000 miles, but not many are there yet. The same can be said for walnut blasting.