2017 Ford Focus St Engine – Your Guide To Power, Longevity, And DIY
The 2017 Ford Focus ST features a 2.0L EcoBoost engine that delivers 252 horsepower and 270 lb-ft of torque in a compact, front-wheel-drive package. This guide explores the technical specifications, common maintenance needs, and performance potential of this popular turbocharged powerplant. Whether you are troubleshooting a check engine light or planning your next modification, we provide the expert insights you need to keep your ST running strong.
If you own a hot hatch, you likely agree that few things beat the rush of a well-tuned turbocharger kicking in on a winding backroad. We promise to provide you with the technical depth and practical advice needed to master your car’s maintenance and performance. In the following sections, we preview the essential specs, common failure points, and the best DIY upgrades for your vehicle.
The 2017 ford focus st engine is a masterpiece of modern engineering, but it requires specific care to stay reliable. Enthusiasts love it for its mid-range punch, yet it faces unique challenges like carbon buildup and heat soak. By understanding these nuances, you can ensure your Focus ST remains a dependable daily driver and a weekend track weapon.
Understanding the 2017 ford focus st engine Specifications
At the heart of the Focus ST lies the 2.0L EcoBoost inline-four. This engine utilizes a BorgWarner K03 turbocharger, which is integrated directly into the exhaust manifold to reduce weight and improve spool times. This design allows the car to produce maximum torque as low as 2,500 RPM.
The block is made of high-pressure die-cast aluminum with iron sleeves for added durability. It uses a Direct Injection (GDI) system, which sprays fuel directly into the combustion chamber at high pressure. This increases efficiency and power but leads to some specific maintenance requirements we will discuss later.
The compression ratio sits at 9.3:1, which is relatively high for a turbocharged engine. This setup requires high-quality fuel to prevent detonation. While the car can run on 87 octane, you will only achieve the advertised 252 horsepower using 93 octane premium gasoline.
Internal Components and Design
Ford engineered this engine with a forged steel crankshaft and powdered metal connecting rods. These components are robust enough to handle moderate increases in boost from aftermarket tuning. The cylinder head features Ti-VCT (Twin Independent Variable Camshaft Timing) to optimize airflow across the entire rev range.
The cooling system is also highly integrated. It uses a cross-flow radiator design to manage the high heat generated by the turbocharger. Keeping this system in top shape is critical for preventing head gasket issues or warped heads during spirited driving.
Common Issues and Troubleshooting for the 2017 ford focus st engine
Every engine has its quirks, and the 2017 ford focus st engine is no exception. One of the most discussed topics in the ST community is Low-Speed Pre-Ignition (LSPI). This occurs when the engine is under high load at low RPMs, potentially causing catastrophic piston failure.
To avoid LSPI, never “lug” the engine. If you need to accelerate quickly while in 6th gear, always downshift to 4th or 3rd to get the RPMs up. This simple habit protects your ring lands and keeps the internals safe from extreme cylinder pressures.
Another frequent culprit for poor performance is the Purge Valve (CPV). When this valve fails, you might experience a rough idle after refueling or a stalling sensation. It is a common DIY fix that usually involves replacing the entire vapor canister purge line assembly.
Addressing Carbon Buildup
Because the 2.0L EcoBoost is direct-injected, fuel never washes over the back of the intake valves. Over time, oil vapors from the crankcase bake onto the hot valves, forming carbon deposits. This can lead to lost power, hesitation, and decreased fuel economy.
Many owners install a Catch Can to intercept these oil vapors before they reach the intake. If your car has over 60,000 miles and feels sluggish, you may need a professional walnut blasting service. This process safely scours the valves clean, restoring original airflow and performance.
The Infamous “Wiring Loom” Rub
Some 2017 models suffer from electrical gremlins caused by the engine wiring harness rubbing against metal brackets. This can cause intermittent misfires or sensor errors. Inspect the harness near the battery box and intake manifold for any signs of frayed insulation or exposed wires.
Essential Maintenance for Your EcoBoost
Consistent maintenance is the secret to a 200,000-mile 2017 ford focus st engine. Oil choice is perhaps the most important factor. Always use a high-quality 5W-30 full synthetic oil that meets the Ford WSS-M2C946-B1 specification.
Change your oil every 5,000 miles, regardless of what the onboard monitor suggests. Frequent changes help remove the fuel dilution common in direct-injection engines. Use an OEM Motorcraft FL-910S filter or a high-quality equivalent like a WixXP for the best filtration.
Spark plugs are another critical item. The ST is sensitive to spark plug gap and heat range. For a stock engine, use NGK Iridium plugs gapped to 0.030 inches. If you are running an aftermarket tune, you may need a “one step colder” plug gapped to 0.026 or 0.028 inches.
Coolant and Transmission Care
The cooling system uses Orange or Yellow Motorcraft coolant, depending on the specific build date. Never mix different colors of coolant, as this can lead to “sludging” that blocks the heater core. Flush the system every 50,000 miles to maintain optimal thermal efficiency.
Do not forget the transmission fluid. While the Focus ST uses a manual MMT6 gearbox, the fluid does break down over time. Replacing the factory honey with a high-performance DCT fluid can significantly improve shift quality, especially in cold weather.
Performance Upgrades for the 2017 ford focus st engine
The 2017 ford focus st engine responds exceptionally well to basic modifications. The first upgrade every owner should consider is an Aftermarket Intercooler (FMIC). The factory unit is notoriously small and “heat soaks” after just one or two hard pulls.
A larger intercooler keeps intake air temperatures (IATs) low, allowing the engine to maintain full timing and boost. This doesn’t just add power; it adds consistency. You will notice the car feels just as fast on the tenth pull as it did on the first.
The Rear Motor Mount (RMM) is another essential “day one” mod. The stock mount is very soft to reduce vibration, but it allows the engine to rock excessively during shifts. Replacing it with a stiffer urethane mount improves traction and eliminates the dreaded “bang” during hard 1-2 shifts.
Tuning and Airflow
To truly unlock the potential of the EcoBoost, you need a COBB Accessport or a similar tuning device. A Stage 1 tune can add 20-30 wheel horsepower and significantly more torque. Always ensure you have the supporting hardware, like a high-flow air filter, before pushing higher boost levels.
For those seeking more sound, a Downpipe and cat-back exhaust system will let the turbo whistle shine. Be aware that a high-flow downpipe usually requires a tune to prevent a Check Engine Light (CEL). It also reduces backpressure, allowing the turbo to spool even faster.
Safety and DIY Tools for Engine Work
Working on the 2017 ford focus st engine requires a few specific tools. A quality torque wrench is non-negotiable, as many bolts on the EcoBoost are “torque-to-yield” or require very specific tightness. Over-tightening a spark plug or an oil pan bolt can lead to a very expensive day.
Always use jack stands when working under the vehicle. Never rely on a hydraulic floor jack alone. The Focus ST has specific jacking points on the pinch welds; using a rubber puck adapter prevents the metal from bending or rusting over time.
Before performing any electrical work or sensor replacement, disconnect the negative battery terminal. The ST’s computer system is sensitive to voltage spikes. A 10mm socket is all you need to safely depower the car and protect your expensive ECU.
When to Call a Professional
While most maintenance is DIY-friendly, some jobs are best left to a licensed technician. If you suspect a blown head gasket or hear internal metallic knocking, stop driving immediately. Diagnosing internal bottom-end issues requires specialized Bore-scopes and compression testers that most hobbyists lack.
Frequently Asked Questions About the 2017 ford focus st engine
What is the best oil for the 2017 Ford Focus ST?
You should use a 5W-30 full synthetic oil that meets Ford’s specific performance standards. Many owners prefer brands like Pennzoil Platinum or Amsoil because they offer high resistance to the heat generated by the turbocharger. Always pair it with a high-quality filter like the Motorcraft FL-910S.
How often should I change the spark plugs?
For a stock 2017 ford focus st engine, change the plugs every 30,000 miles. If the car is tuned or driven hard at track events, inspect them every 10,000 to 15,000 miles. Correct gapping is essential to prevent misfires under high boost.
Does the 2017 Focus ST engine have a timing belt or chain?
The 2.0L EcoBoost engine uses a timing chain, not a belt. This is a significant advantage for long-term reliability, as the chain is designed to last the life of the engine. However, you must maintain proper oil levels to ensure the chain tensioners function correctly.
Why does my Focus ST idle roughly after getting gas?
This is almost always caused by a failing Evaporative Emission (EVAP) Purge Valve. When the valve sticks open, fuel vapors from the gas tank flood the engine, causing it to stumble. Replacing the purge valve assembly usually solves the problem immediately.
Conclusion and Final Tips
Owning a 2017 Ford Focus ST is a rewarding experience for any driving enthusiast. By staying proactive with your maintenance and understanding the unique needs of the 2.0L EcoBoost, you can enjoy years of turbocharged fun. Remember to avoid low-speed lugging, keep your intake valves clean, and always use high-quality synthetic fluids.
Whether you are keeping your car 100% stock or chasing 350 horsepower, the key is consistency. Listen to your engine, watch your gauges, and don’t ignore small leaks or strange noises. With the right care, your Focus ST will remain a formidable force on the road for a long time to come.
Stay safe, keep the shiny side up, and enjoy every mile behind the wheel of your ST!
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