What Are The Most Common Issues With Subaru FA20 Engine?

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The Subaru is one of those vehicles that is trusted and bought by thousands of people. The reason for this is that it has amazing performance. What makes this performance output possible is the FA20 engine that is under the hood.

Although the FA20 engine racks up many points in the positive department, some issues come associated with it. You should be aware of that.

So, let’s take a closer look at the Subaru FA20 engine problems:

  1. Failure Of The Connecting Rods
  2. Carbon Build-Up In The Engine
  3. Poor Factory Tuning
  4. Failing Valve Springs

Unlike some engines, whose issues are not that serious, all of these four above are deemed critical. This article will explain why these issues occur and what can be done to resolve them.

The 4 Most Common Subaru FA20 Engine Problems

As stated in the introduction above, we will now discuss the four issues I outlined above. At the end of this page, you will find an FAQs page that will help in eliminating any confusion.

1. Failure Of The Connecting Rods

Function

Connecting rods is not something that is exclusive only to the Subaru. Every vehicle that has a piston layout, which is almost all vehicles, uses connecting rods. Now, what is the function of connecting rods?

Well, they connect the piston to the crankshaft. The rod does the work of converting the movement of a piston into the movement of the crankshaft.

In basic terminology, the connecting rod transfers the motion from the piston to the crankshaft.

The Issue

You may have already assumed that without the connecting rods, the Subaru FA20 engine would not be able to function at all. Users reported that the rods started failing when they tried to upgrade the performance of their vehicles.

As the engine is a turbo one, boosting its HP and torque is quite an easy task. A simple tuning could be all you need to get the job done.

So, why does this happen? There are several different reasons for this. Let me write down some of them before:

  • High engine speeds.
  • Piston hitting a valve.
  • Incorrect installation of the rod.

As suspected, the first two causes may be due to an HP increase. In the short term, it can be concluded that the connecting rods can handle only stock power levels.

Repair

Depending on the severity of the issue, you can expect to pay too much to get this issue resolved. Simply replacing the rods will not get the job done. You may even need to rebuild the entire engine for it to become functional again. If that is the case, you can easily expect the costs to be north of the $5000 ballpark.

Although you can drive with a rod knock, these rods could fail catastrophically at any second. The broken rod can, in turn, damage the engine severely. It is not worth it to risk that much.

2. Carbon Build-Up In The Engine

Now, this next problem is the one that was faced by users the most. Many Subaru owners complained that their engines suffered from carbon build-up. Let us find out the reason for this issue and how to fix it.

Why It Occurs

So, why does the FA20 engine have carbon deposits? Well, the culprit of the problem is direct injection. As some engine variants use direct injection to spray fuel directly into the nozzles, there is some blowback.

This is perhaps the only disadvantage of this technology. The blown back oil settles in the intake tracts. As the process is quite slow, the intake ports and valves get clogged up over the years.

Getting The Issue Fixed

So, what can someone do to fix the build-up issue in their FA20 engine? Well, there is only one real fix for this issue, and that is called walnut blasting. The intake manifold is removed during this process, and all of the intake tracts are blasted with walnut media shells. This clears up all of the deposited carbon.

The cost of this solution is in the ballpark of $500. You don’t need to get this done now and then, but it is better to get it checked and done after every 100000 miles.

Symptoms Of Carbon Build Up

Although the process of carbon depositing is very slow, there are some symptoms in the later stages of the process. They will confirm if you have a build-up in the engine.

Some of these symptoms are:

  • Unexpected misfires.
  • Hesitation while accelerating.
  • Sudden power loss.
  • Rough idling.

As you may have expected, all of these issues will severely affect your daily driving experience. These symptoms should not be avoided. They could be caused due to other underlying problems, but carbon build-up has the highest probability of displaying these symptoms.

3. Poor Factory Tuning

Background

Now, this third issue can be blamed fully on Subaru. The tuning of a vehicle is extremely important to make sure it performs adequately. It controls how much HP is generated and how much fuel is consumed.

As many of you may know, a vehicle needs to be tested thoroughly to make sure the best settings have been applied after a tuning. Well, I don’t think that was the case when Subaru designed this engine.

The Issue

As tuning is software-related, some settings can be tweaked to adjust the performance of the car. Well, users reported that the tuning on the engine was pretty bad in some cases. Users reported that their engines had the issue of not running smooth or the boost being too aggressive.

So, how did a company like Subaru mess this up? The thing is, they didn’t. There have been reports of engine inconsistencies, but nothing major was reported. Now many of you may be confused as to what the issue is.

Well, most people who were informed about this problem did not know that the engine had a direct injection system. This causes the engine to be too lean or too aggressive while boosting.

Fixing The Tuning

If you own a Subaru with the FA20 engine under the hood, then there is a chance that you may not be satisfied with the answer I provided you. Well, the only solution to the problem is to get a tuner of your own. It will connect to the OBDII port of the vehicle, and you can set the performance to your liking.

You could also visit a mechanic to get the job done, but it will cost you many. It is a lot cheaper to get a tuner and perform the procedure yourself. It is recommended to get tuners from reputable brands as you risk wiping the ECU.

4. Failing Valve Springs

History

Now, this final issue is found on the naturally aspirated variant of the engine. There were no reports regarding this issue when it came to the Turbo variant. This is the only problem in this article that led to the conglomerate issuing a widespread recall.

The Problem

Although it is quite serious when vehicles ship with faults, I find it extremely satisfying when I find out that the company acknowledges its mistakes and recalls its vehicles. It means that the company knows and wants to fix the issue for you.

Further Problems

Regardless, users complained about failing valve springs. This was due to them not being constructed properly. The thing is, the problem does not end there. Replacing the valve springs is already a time-consuming one, which takes around 10 hours; users reported that it was not done correctly.

They complained that too much sealant was used, which when mixed with the engine oil. This issue is quite serious because if the engine is not lubricated properly, it could lead to various issues. Some users complained that their engines completely died to there being too much sealant.

It was quite surprising to see something as serious as this happen with a manufacturer like Subaru. The company messed up the process.

For those who didn’t read this through, the company recalled vehicles to fix an issue but created more problems for the users. The issue made the rounds in many headlines on the internet. It was quite a big fiasco that affected the company’s reputation.

What Is The Subaru FA20 Engine?

The Subaru engine was released alongside Subaru BRZ. It was also featured in the Toyota 86 and the Scion FR-S. The engine is quite interesting. It was mainly built on the FB20 architecture. The square shape of the motor allowed the engineers to reach a 1:1 bore/stroke proportion.

The engine’s compression index is a very impressive 12.5:1. In terms of fuel injection, Toyota had a hand in it. It was the direct fuel injection system, which allowed the engine to produce more horsepower. Of course, it has some drawbacks, but the technology is quite successful.

Is The Subaru FA20 Engine Reliable?

This is a complicated answer. Yes, the engine is reliable and will not cost you too much in terms of maintenance, but when something goes wrong, the chances are that many other parts of the engine will be affected too. Take the connecting rod problem, for example. The issue can damage many other engine parts.

The same can be said for the carbon build-up issue. So, if you safely drive your Subaru and keep it maintained at all times, then you will not run into such issues. For those of you who do this, the engine is very reliable.

What Cars Use The Subaru FA20 Engine?

The engine has been used on some vehicles. Subaru was not the only company to use it because Toyota owns a part of it. So, these two companies shared the ownership of this engine.

The naturally aspirated model was used in three vehicles. The Subaru BRZ and the Toyota GT86 used this engine. They used it from 2012 to 2020. The Scion FR-S also was introduced with this engine.

The turbo variant, the FA20F, was used in four different vehicles. The Subaru Legacy, the Leborg, and the ever-popular WRX were the ones that use this engine.

Yes, that’s right, as of 2021, these vehicles still ship with the same engine. The Forester also used this engine but only for four years, from 2014 to 2018.

Subaru FA20 Engine Specs

Cylinder block composition Aluminum
Cylinder head composition Aluminum
Fuel Gasoline
Fuel injection type Direct injection
Arrangement Inline, Turbo
No. of chambers 4
Valves in each cylinder Valves in each cylinder
Valvetrain layout DOHC
Bore 86 mm or 3.39 cubic inches
Stroke 94mm or 3.70 cubic inches
Displacement 2.0L or 1998cc
Internal combustion engine (Type) Four stroke, Naturally articulated, Turbocharged
Compression ratio 10.6:1, 12.5:1
Power 197 – 296 HP
Torque 151 – 295 lb. ft
Weight of engine oil SAE 0W-20
The capacity of engine oil 5.7 quarts w/filter
Firing directive 1-3-4-2
The interval between oil change/strong> 6000 miles (10000 km) or six months

The Benefits Of Choosing The Subaru FA20 Engine

The engine has many advantages, apart from being a very decent performer:

  • Has a direct fuel injection system.
  • Better injection control.
  • Higher compression ratio.
  • It is a turbocharged engine.

FAQs

What Turbo Does The FA20 Engine Have?

The FA20 engine has a Twin-Scroll Turbocharger installed in it. The engine produces a respectable 272 HP and 258 lb. ft. The performance should be plenty for most people. Anyone who does not use their vehicles for heavy-duty purposes will find the engine perfect for them.

How Heavy Is The FA20 Engine?

The engine is quite lighter than other engines I have checked out. It is only 480 pounds in weight. This is a decent weight and working on the engine becomes considerably easier.

Does The FA20 Engine Have Forged Internals?

Yes, it does. The engine used ultra-strong 2618 aluminum to forge the internals. The engine also features injection bowls which have been designed to be compatible with the fuel injection system.

Conclusion

So, there you have it, avid readers, my take on the Subaru FA20 engine problems. The company has created a solid engine that has been in use for almost a decade. Although it does have its fair share of problems, its overall performance is very solid.

Users were very impressed with what it could do, and it still is lightweight, being under the 500-pound limit. Talking about reliability, I think the engine is quite reliable, and if you choose to get a vehicle that is equipped with it, it will exceed your expectations. With a good fuel consumption and power output, it is enough for most people.

Resources:
1. https://tuningpro.co/the-4-most-common-subaru-fa20-engine-problems/
2. https://www.motorreviewer.com/engine.php?engine_id=72