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Repair Summary
This article covers replacing both the spark plugs and ignition coils (also known as a "tune up") in a BMW F30 3 series vehicle with the N20 engine. The N20 engine is also used in a wide range of other BMW models including the 1,2,4,5,X1,X2,X3,X4 and Z4 series cars and SUVs. This article can be applied to any vehicle with the N20 engine with minor modifications to the repair steps.
See all vehicles this article applies to
F30 3 Series 318d
F30 3 Series Hybrid 3
F30 3 Series 335iX
F30 3 Series 335i
F30 3 Series 335dX
F30 3 Series 330d
F30 3 Series 330dX
F30 3 Series 328i
F30 3 Series 328dX
F30 3 Series 328d
F30 3 Series 328iX
F30 3 Series 320iX
F30 3 Series 325d
F30 3 Series 320i
F30 3 Series 320i ed
F30 3 Series 320dX
F30 3 Series 320d ed
F30 3 Series 320d
F30 3 Series 318dX
F30 3 Series 316i
F30 3 Series 316d
A BMW F30 spark plug replacement can help cure a rough idle and poor performance in your N20 turbocharged engine.
In 2011 BMW introduced the N20 four-cylinder turbocharged engine into its model line up. It was to be the successor to the venerable line of normally aspirated inline 6 cylinder engines that had powered most of BMW's vehicles since the late 1980s. The inline turbocharged four-cylinder N20 produces the same horsepower and torque as the larger six-cylinder engines in a more fuel and weight-efficient package.
There have been reports from BMW F30 3 series owners of a noticeable decrease in performance around 40-50,000 miles including poor acceleration, rough idle, engine stalls, and fluctuating low-speed RPMs (like when "rolling" to a stop with the foot off of the accelerator). Many of these issues are directly attributable to failing spark plugs and ignition coils in their N20 engines.
The BMW Service and Warranty Book for the F30 3 series recommends changing the spark plugs in your 2012-2019 3 series every 60,000 miles. Based on the information we have accumulated from F30 owners, we feel this is too long a period. The BMW Repair Guide recommends replacing the spark plugs in your N20 engine every 40,000 miles to keep your vehicle performing normally. There are no recommendations on ignition coil replacement in the service and warranty book, but we feel it is good practice to always change them out with the spark plugs.
A BMW F30 spark plug and ignition coil replacement is a straightforward repair that can be completed in about an hour. It involves replacing the ignition coils and spark plugs in the four cylinders. The good news is the cylinders in the N20 engine are easily accessible - a minimal amount of engine parts have to be removed to complete this repair. Doing your own BMW F30 spark plug replacement is a big money saver as well...it can be performed in your garage for a fraction of the cost charged by the dealership or your local repair shop.
View the detailed parts diagram for this repair.
Includes detailed part diagrams, part numbers and links to purchase all of the required components needed to complete this repair.
Before starting this repair, you must have the following required parts.
Genuine BMW, kit includes four plugs
Don't be fooled by aftermarket manufacturers that claim their plugs are "OEM". There is only one trusted source for factory spark plugs...Genuine BMW. These are the same factory plugs that would be installed at the dealership.
All vehicles with N20 four cylinder engine
Sluggish acceleration, misfires and rusty terminals are symptoms of a worn coil. Located on the top of your engine, these coils should be inspected replaced as needed or every 100,000 miles. Keep your ignition system in perfect order.
BMW F30 320i and 328i
The air filter must clean 8000-9000 gallons of air for each gallon of fuel burned inside the engine, without restricting the air intake.
Air filter replacement at recommended intervals lets an engine breathe properly while protecting it from costly damage. Air filters should be inspected and replaced as needed at least once a year, more often if the vehicle is driven in heavily polluted or dusty conditions.
Section 1 - Prepare the Engine for Removing the Spark Plugs and Ignition Coils
Preparing the engine so the N20 spark plugs and ignition coils can be accessed is a relatively easy procedure taking less than 15 minutes. Please note that it is important that the strut braces are loosened (step 9) to create enough space to get the upper partition out without breaking it.
- Always disconnect the negative terminal of your vehicle's battery before starting this repair. Since you will be working in the engine compartment with metal tools near a live positive terminal, failure to disconnect the battery could create a short circuit causing catastrophic damage to sensitive electronics.
- Begin by removing the engine cover. It is held in place by three rubber mounts. Simply pull it free from its mounting bracket and remove it from the engine compartment.
- Remove the sound insulation from the top of the engine.
- Use a 10mm nut driver to release the three plastic locking mechanisms on the right apron. Grasp the apron and remove it from the engine compartment.
- Repeat the same procedure on the right apron.
- In order to gain access to the rear number 4 cylinder, the top equipment partition must be removed. Begin by removing the seven 10mm bolts anchoring the partition to the body of the car.
- Remove the rubber engine sealing gasket from the partition.
- Remove the wiring harness from the sealing gasket. Remove the sealing gasket from the vehicle.
- Use an E18 external torx socket to remove the two strut brace bolts. You will need to remove these bolts so the strut braces can be raised just enough to allow enough room to remove and reinstall the top partition.
- Lift the strut braces and maneuver the top partition underneath them. Remove the partition from the vehicle.
- You now have clear access to all four cylinders.
Section 2 - Replace the Spark Plugs and Ignition Coils
The four BMW N20 spark plugs and ignition coils are very easily accessed on the right side of the engine. The BMW Repair Guide strongly discourages the use dielectric grease on the ignition coils during reassembly - dielectric grease can cause the coils to slip off of the spark plugs causing misfires.
- Starting with cylinder number one, release the plastic locking clip on the ignition coil and remove its plug.
- Pull the ignition coil off of the spark plug. Use a socket extension to assist pulling it out if necessary.
- Using a 14mm thin wall spark plug socket, remove the spark plug from the cylinder.
- Apply a small amount of anti seize lubricant to the new spark plug.
- Install the new spark plug and hand tighten.
- Using a torque wrench, torque the spark plug to 25 Nm (18 ft-lb).
- Insert a new ignition coil into the spark plug tube and install the electrical plug. Make sure the plug is pushed in snugly as far as it will go into the ignition coil. DO NOT apply dielectric grease to the ignition coil...this will cause the coil to slip off of the spark plug causing a misfire.
- Push the coil firmly down onto the spark plug using the palm of your hand.
- Repeat the above steps on the last three coils.
- Before reassembling the vehicle, start the engine and check to make sure it is running smoothly.
Section 3 - Reassembling the Engine
- Reinstall the top partition and its seven mounting bolts.
- Reinstall the strut brace bolts and torque to 25 Nm (18 ft-lb).
- Reinstall the engine sealing gasket and its wiring harness. Make sure the gasket is correctly seated on the top partition to avoid and water and debris from entering the engine.
- Install the aprons making sure they are securely snapped in and the locking mechanisms are secure.
- Reinstall the sound insulation and the engine cover.
BMW F30 Spark Plug Replacement Finished
