Basic Maintenence
By: Brent Ackley
The LTG being a Direct Injected Turbocharged engine is more likely to experience LSPI or low-speed pre-ignition. Piston Ringlands, and Pistons are a common failure on these motors because of this. Here are a few things you can do to help combat this and other common issues across our platforms.
Oil
Make sure you are using an oil that has an API rating of SN Plus. This is the latest standard for LSPI preventive oils and is a revised version of the later SN rating that was updated as of November 9, 2017. This signifies the oil is formulated specifically for Turbocharged Direct Injection vehicles and it has passed the latest standardized test to prevent LSPI.
5w30 is fine on pump gas, If running Ethanol then think about running 0w40, 5w40, or 5w50 to combat fuel dilution on our GDI motor.
Catch Cans
Make sure you're using a catch can to prevent any contaminants from crankcase vapors from reentering the engine this will also help to reduce build-up on the intake valves. Companies that make them for our platforms are Tracy Lewis (The Best by far), RXP, Mishimoto, and ZZP or you can source your own materials and build a custom setup. It is highly recommended that you not run an aftermarket intake or intake tube without one as the white plastic ‘Silencer’ most people remove acts as a makeshift catch and can collect oil coming from the PCV so it is not being sucked directly into the turbo and making its way to the intake track.
Spark Plugs
Change to a colder heat range spark plug. A colder range plug is less likely to retain heat and cause preignition and as some of you know a TSB/Recall was issued on the earlier engines to make changes to the tune as well as install colder plugs. From my research, most companies are recommending changing over to the Denso ITV24 (PN 5341), NGK 6510, or the ITV22(PN5340) for moderate builds or if you do not plan to tune the car and gap will differ depending on the boost level you’re planning to run with most saying to run in the low .030-.028 range. For more information on this check out this article from Denso and how it relates.
MAF
The MAF or Mass Air Flow sensor is located either in the intake tube on aftermarket intakes or in the outlet of the factory airbox. This sensor is crucial to determining how much fuel the car needs in relation to airflow. If you are running an oiled filter such as the K&N it is recommended you use an approved MAF Sensor Cleaner and periodically clean the sensor to make sure an oil film has not covered the element inside the sensor. The sensor contains a heated element that tries to maintain a constant temperature it does this by reading the number of pulses in Mega Hertz to calculate how much air is being moved across the element in conjunction with other sensors that monitor things such as barometric pressure and humidity. If the element is covered in a film of oil the incoming air is not going to have as much of an affect on the element as it is being insulated by the oil from the air rushing over it. Running the car with a dirty MAF may skew the commanded AFR and result in the car running slightly lean which can over time cause engine damage. This may cause a ‘System Lean’ CEL if left unattended as the sensor will report less air flow than what is actually occurring.
Check your Hoses
Specifically the hard plastic PCV lines under the engine cover as they are known to crank over time due to prolonged heat cycling. These lines breaking can cause a vacuum leak and a check engine light for ‘System Lean’ that may come and go as it pleases. Also check the overflow hose that runs from the radiator and turbo (connects under the engine cover). This hose is famous for leaking at the hard plastic connection and causing a slow coolant leak. It has also been reported that the hose clamp on the overflow will weaken over time and you may see a slight leak at this connection and the short jumper piece under the engine cover that runs between the two hard lines that get coolant from the turbo. Joseph at Colorfittings.com is working on a kit to replace this line with a very high-quality braided line and AN fittings to make sure you are leak-free and looking great while doing it.
Driving Habits
Mainly referring to lugging the engine. At all costs avoid putting the car into a low-speed high load scenario. The stock shift strategy is terrible about this as they're mileage-minded. Trying to accelerate while the car is at a low RPM, for example under say 2800-3000, you may feel the car shudder similar to driving a standard and trying to take off in too high of a gear. This scenario creates high cylinder pressures and combined with the aforementioned LSPI is, in my opinion, one of the main causes of the dreaded cracked ring lands. With some experimentation you can feel out the car and learn to vary throttle inputs to drive around this or better yet have the transmission tuned by a reputable tuner that has experience with our platform. The other topic that relates to driving habits relates mostly to those on the stock tunes. These cars run fairly lean during most normal driving and part throttle pulls. They will run fairly rich at WOT for a direct injected platform but seeing that most of us use the pedal not as an on-off switch keep in mind the lean factory tune will result in high EGTs or exhaust gas temperatures if you're making long high-speed pulls or consecutive pulls. This will result in actually melting pistons if you push it far enough. This can also be combated, to an extent, by having the car tuned by someone familiar with the platform.
Induction cleanings
Being that this is a Direct Injected engine we no longer have the cleaning effect of the fuel spraying the back of the intake valves. Over time oil and other contaminants will bake onto the back of the intake valves and in the bowl section of the port. This build-up can obviously disturb air flow, cause poor idle conditions, and up to carbon chunks falling into the chamber can become hot enough to create an ember and ignite fuel causing LSPI. This goes back to using the proper ‘Low Ash’ oils with the correct API ratings. There are a few methods that can be used to clean the ports. Walnut blasting is the BMW dealer-approved service which does require removing the manifold and going port by port to blast the areas clean turning the engine over by hand to make sure the valves are closed. Aerosol/Liquid type cleaners can also be used. Brands like Seafoam, BG Products, and Im sure there are countless others. These work typically by spraying them into the intake system and results can vary. I suggest doing research either way and find what you're comfortable with. Water-Methanol Injection is also a great way to keep these clean as it basically steam cleans it as you drive the car but this does require a knowledgeable tuner to make the correct changes to the tune to run properly, again do your own research if you plan to go this route and see if it’s the best fit for your car.
I hope this will help you guys and I will add anything going forward that we learn along with any more tech info, links, etc.
