Really, it’s not just the 335i I’m talking about – it’s anything with the N54 twin-turbocharged inline-six engine. Certain years of 135i, 135is, Z4 sDrive35i, Z4 sDrive35is, 335is, 535i, X6 xDrive35i – all that stuff. The N54 is a neat engine, but almost everything bolted to it is terrible. The turbochargers develop wastegate rattles that require serious hours to repair, the plastic valve cover cracks, the charge pipes leak, and the high-pressure fuel pump can go bang. However, most of these pale in comparison to the issue of fuel injectors. The N54 uses piezoelectric direct fuel injectors, and because it’s a fairly early application of this tech on a gasoline engine, they tend to go a bit wrong. BMW had to revise injector design 11 times during the engine’s production, eventually landing on the latest Index 12 injectors. However, Index 12 injectors can still fail, and you’re not ready to hear what each replacement injector costs. Take a deep breath. From reputable online retailer FCP Euro, Index 12 injectors for the N54 inline-six cost $549.99 each. Yes, each. What’s more, it’s not recommended to mix Index 12 injectors with Index 1-10 injectors as a calibration change occurred for Index 11, which means that it’s recommended to replace injectors bank-by-bank. Considering an N54 has two banks of three cylinders, this means a minimum outlay of $1,649.97. If you want the peace of mind of replacing all six in one go, that’s $3,299.94 worth of fuel injectors. That’s enough to mechanically total a high-mileage E90 335xi. Index 12 injectors weren’t always this expensive, so what the hell happened? In short, there was a parts structure change. The updated fuel injectors for the N54 engine carried a part number of 13538648937 and were made unavailable outside of recall or warranty work in 2018. However, they were basically identical to the then-recently updated direct injectors found on the S63 V8, part number 13538616097. Both part numbers have since been combined under part number 13538616079, still identical to the injectors on the S63, albeit much more expensive than before. So are there any aftermarket alternatives to these pricey VDO-manufactured injectors? Yes and no. There are companies out there that promise to rebuild these fuel injectors. However, rebuild quality varies wildly, so it’s a roll of the dice on whether you’ll need to just buy brand new injectors anyway. I’d also advise against ordering cheaper injectors from eBay as many are counterfeit with improper calibration values printed on the parts. As replacing N54 injectors requires registering the new injectors in the engine control module, punching in correct injector calibration values is critical to avoid misfires. As it sits, there is no cheap way to properly replace N54 fuel injectors according to servicing guidelines. It’s a painful reminder that once-bleeding-edge technology will always be expensive to keep going as few first shots are ever perfect. If you’re in the market for an N54-powered BMW, it’s a good idea to ask for service records and see if the injectors have ever been replaced. If all six are now Index 12 injectors, you’re likely in the clear. If not, be sure to keep a few grand lying around for when the inevitable happens. Really, that’s good German car advice in general. Lead photo credit: BMW
- Multiple injector banks replaced 2) Multiple high pressure fuelpumps 3) Wastegate 4) Plastic oil pan cracked, leaked and stranded me 5) Multiple airbag occupancy mats (had to leave the belt clicked) 6) Water pump failed and shot water all over the alternator, taking it and the electrical system with it I finally donated its carcass to a radio station. It was six years old. By then all the plastics on the inside were turning to goo. What a mess of a car. However, if you are a glutton for punishment and keep the BMW, at least you will only have to buy these injectors once due to the crazy FCP guarantee! https://www.fcpeuro.com/page/lifetime-guarantee On the other hand, sometimes they forget how to bolt on the wheels in such a way that they don’t just fall off right after the car gets on the road. Whaddaya gonna do? You can get turbos for as little as US$359, valve covers can be had for as little as US$135 and the HPFP can be had for only US$1400. The other stuff is also unavailable. On the bright side. the wastegate rattle thing looks like a no-cost DIY fix… I saw a youtube video on it But aside from that, this article reaffirms why I avoid Euro luxury cars and how “German Quality” is a joke… particularly when it comes to BMWs and VAG products. “ticking time bomb”? Sure, only if you decide that routine maintenance is optional. But this would apply to any car then, wouldn’t it? The fuel injectors got replaced, as per the schedule, at 100k miles. This was in 2018. We used an indie BMW specialty shop, who used a quality aftermarket part. But assuming I was the kind of person who can’t RTFM regarding scheduled repair or replacement is parts, you think $3300 is enough to total a car? Seriously? The math is this: $3300 on a scheduled repair on a fully paid off garage kept car that runs really well and could run well for several more years vs spend cash or take on a monthly payment on a CPO or new car for several years, which costs WAY more than $3300 in the long run, and would likely increase my insurance costs. Also, many of the problems you describe occur if you drive the car hard all the time, and then forget to follow a more frequent maintenance schedule befitting that kind of usage. If you use it as a DD, the only thing I recommend beyound routine things is replacing all the coolant hoses to the braided stainless steel, and every 75k replace the water and fuel pumps. But….I would do that for any car.
