The Four Most Frequent Subaru FA20 Engine Issues

The Four Most Frequent Subaru FA20 Engine Issues. The 2.0 Subaru FA20 engine debuted in 2012, with two variations available. FA20D engines are non-turbo and use direct and port injection. The FA20F, on the other hand, employs a twin-scroll turbo and direct injection. Wards Auto 10 best engines accolade went to both types of the Subaru FA20. They’re fantastic engines that provide an excellent blend of performance and efficiency. Nevertheless, flawless engines do not exist, and there are no exceptions. This article discusses common difficulties with Subaru FA20 engines and concludes with general ideas on reliability.

The Four Most Frequent Subaru FA20 Engine Issues

FA20 Engine Specifications and Information

The fundamental specifications of the FA20D and FA20F engines are listed below. It’s worth noting that the Subaru FA20F is also known as the FA20DIT, which stands for “direction injection turbocharged.”

The Four Most Frequent Subaru FA20 Engine Issues

The specifications of the two engines are comparable, as indicated above. They do, after all, share the FA20 engine family. The FA20D has no turbo, although it does have port and direct fuel injection. In the meantime, the Subaru FA20DIT gets a twin scroll turbo but no port injection. To enable the greater power and boost, the turbo variant’s compression is reduced from 12.5 to 10.6. Otherwise, the Subaru FA20’s basic design is essentially identical.

FA20D Subaru/Toyota

Subaru and Toyota cars with naturally aspirated FA20D engines include:

The FA20F Turbo

The Subaru FA20F turbo engine is available in the years and models listed below:

  • Subaru Legacy 2.0GT 2012+
  • Subaru Leborg 2014+
  • Subaru WRX 2015+
  • Subaru Forester 2014-2018

4 Common FA20 Engine Issues

Among the most prevalent issues with the Subaru FA20 engine are:

  • Carbon accumulation
  • Rods for connecting
  • factory tuning
  • Spring-loaded valves

We’ll go through these issues in detail throughout the rest of this essay. However, before moving on, it’s a good idea to add a few notes. These are some of the most prevalent Subaru engine problems. It doesn’t mean they’re frequent or affect a high percentage of vehicles. Also, the majority of the issues we’re mentioning are related to the FA20DIT turbo engine. We will discriminate between the engines as needed. That being said, let’s go over each of the aforementioned FA20 engine issues.

1) Carbon Build-Up on the Subaru FA20

In many contemporary engines, we find ourselves writing about carbon buildup. Direct injection (DI) is a fantastic technique that helps the FA20 engine perform and run more efficiently. DI, on the other hand, has a few problems of its own, one of which being carbon build-up. Carbon build-up is not an issue with the FA20D because it uses port and direct injection.

Why is this issue limited to the Subaru FA20DIT? Direct injection squirts all of the fuel straight into the cylinders. Oil blow-by occurs naturally in engines and travels through the intake tract. Oil blow by finally finds its way onto the intake ports and valves, where it forms carbon deposits. Fuel is injected in this location via port injection to wipe away oil deposits.

Once considerable carbon buildup occurs, the cylinders no longer receive optimal air flow. This is due to the deposits shrinking the intake ports over time, which might cause drivability concerns. Carbon buildup on the Subaru FA20 is expected to be an issue every 60,000 to 100,000 km. It’s not a major issue that requires immediate attention.

Signs of FA20DIT Carbon Buildup

The following are symptoms of high carbon buildup on the FA20 turbo direct injection engine:

  • Misfires
  • Idle time
  • Stuttering or hesitancy
  • Power outage

Misfires are frequently the beginning of difficulties with carbon deposits on the intake valves. You’ll probably notice harsh idling as well as stuttering or hesitation when accelerating. The FA20 will lose power when the cylinders receive less airflow. Yet, because carbon build-up occurs over time, this symptom is sometimes difficult to notice.

Subaru FA20 Carbon Deposit Removal

Cleaning up carbon deposits using walnut blasting is probably the most effective method. To access the intake ports and valves, the intake manifold must be removed. The carbon deposits are subsequently removed with a shop vac and walnut medium shells. Because the materials for the job are quite inexpensive, the fix is primarily labor-intensive. Walnut blasting the FA20DIT intake valves will cost between $400 and $600. Again, it’s not an urgent job, but it’s good to do every 60,000 to 100,000 miles.

2) FA20 Engine Connecting Rod Issues

This may not be fair to include on a list of common FA20 engine failures. Yet, it’s worth mentioning because the turbo engine is simple to tune and modify. With factory FA20 engines, connecting rods aren’t a major issue. They could still fail, but it’s quite unlikely. When you start adding more boost and torque, things change.

FA20F connecting rods are known to be a source of problem in the 325-350 torque range. It’s not difficult to get the Subaru FA20 turbo engine into that range with a tune and some modifications. Again, at stock power levels, this isn’t a huge issue.

Still, it’s important mentioning because connecting rod failures are a big problem. If a rod bends and starts knocking, the FA20 engine will need to be rebuilt. In the worst-case scenario, you may require a whole new engine. It’s not the kind of failure you want to encounter, but if you intend to modify the FA20, you should be aware of the possibility. We’ll skim through the symptoms and treatments for connecting rod issues. Instead, in the following part, we’ll discuss a few risk-mitigation strategies.

Lowering the Chances of Subaru FA20 Rod Failure

Several methods for lowering the danger of connecting rod difficulties on the FA20DIT engine include:

  • Maintain a boost pressure of less than 22 psi.
  • Reduce low-end torque
  • Tuning that is conservative
  • Data-logging

The first three points are related. On the FA20 engine, stick to conservative tweaking. Keep boost at 21-22psi and watch out for low-end torque. The pistons move more slowly at lower RPMs. This exposes the engine to high pressures for a longer length of time, increasing the likelihood of pre-detonation. Bending rods on the FA20DIT is frequently caused by pre-detonation, especially when pushed near the safe limits.

Instead, log data often. Keep a watch on the fueling, AFRs, ignition timing, and so forth. If you see too many timing pulls, consider altering the tune to pull some timing out. Lean AFRs are risky, therefore this is another important data point to monitor. We’ll produce some tuning and mod guides for the FA20 engine in the future and delve more into these issues.

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3) Subaru FA20 OEM Tuning Problems

We’ll be working through this topic quickly. Several FA20DIT owners are dissatisfied with the stock engine software (“tune”) that comes with the vehicle. There have been reports that it is quite aggressive on boost, isn’t smooth, runs too skinny, and so on. Proper engine software necessitates a significant amount of effort and knowledge. Individuals also have varied methods for tuning and configuring engines.

There may also be some misunderstandings. With a direct injection engine, the Subaru FA20 can run a little leaner than standard port injection engines. Many used to complain that the stock BMW N54 tune was far too lean. In actuality, most of them were simply unaccustomed to the nature of DI.

The point is that we do not entirely believe the complaints regarding the factory software on the FA20 engines. Most owners are unlikely to detect any problems. It’s also simple to use a tuner to get the tone exactly where you want it. As a result, we don’t believe this is a genuine issue with the FA20.

The Four Most Frequent Subaru FA20 Engine Issues

Failures of FA20D Valve Springs

Okay, we’ll be brief on this as well. We strive not to include recall-related concerns in any common problem posts because they are issues that the manufacturer is aware of and working to resolve. The FA20D valve spring issues, on the other hand, are an intriguing topic. Because there is no known serious issue with the FA20DIT turbo motor, we are specifying the normally aspirated engine here.

Meanwhile, Subaru and Toyota issued a recall for valve springs on the FA20D engine in the Subaru BRZ, Toyota 86, and Scion FR-S. That’s great – they found a problem and attempted to assist owners with a lengthy and pricey recall. The task entails extracting the engine to remove the valve springs and takes more than ten hours to complete.

However, some owners have reported further issues following the valve spring replacement. It is possible that the IT technicians working on the recalls are applying too much sealant, which is subsequently mixed with engine oil. That eventually resulted in a few engine breakdowns. It appears to be mostly affecting the FA20 engine in the Toyota 86. We’ll leave it at that because this is a hotly debated topic with plenty of information flying around.

The Subaru FA20’s dependability

Are the engines in the Subaru FA20 and FA20DIT reliable? In terms of dependability, we rate the Subaru FA20 as average. It could possibly make more than the average, but there are still some unknowns. The NA Subaru FA20D engine does not have many typical faults. However, there is the valve spring recall nightmare, although it’s difficult to blame the company too much. New engines will always have a few quirks to iron out.

The FA20DIT, on the other hand, has a few more prevalent flaws. That makes sense because turbo engines are more sophisticated and have more parts that can fail. It’s odd that Subaru omitted port injection because DI only causes carbon buildup issues on the FA20. Otherwise, keep an eye out for connecting rod failures at higher than standard power and torque. The FA20DIT is simple to tune and modify, but this can drive the rods above their safe top limits.

Having said that, the FA20 engines are overall robust engines that provide a good blend of reliability, performance, and efficiency. Maintain them properly, and you should have a pleasant experience for many years to come.