The SP Turbo Kit is one of the most popular forced-induction upgrades for the Subaru BRZ, offering a reliable path to 300+ wheel horsepower on a stock FA20 engine. Enthusiasts choose this kit for its clean packaging, reasonable cost, and proven results. However, no aftermarket turbo system is immune to teething problems. Boost leaks, fuel delivery hiccups, and tuning mismatches can frustrate even experienced builders. This guide walks you through the most common issues with the SP Turbo Kit, explains root causes, and provides step-by-step fixes to keep your BRZ running strong. Whether you are a do-it-yourself owner or a shop technician, the troubleshooting steps below will save you hours of diagnostic time.

Understanding the Most Frequent Problems with the SP Turbo Kit

After installing the SP Turbo Kit, owners have reported a handful of recurring complaints. Recognizing these early allows you to diagnose and correct them before they cause serious engine damage. The most common issues include:

  • Boost leaks at intercooler piping or couplers
  • Insufficient fuel delivery under high boost
  • Engine knocking or pre-ignition
  • Turbo lag that makes the car feel sluggish off boost
  • Blue or white exhaust smoke indicating an oil leak

Each of these symptoms points to a specific hardware or tuning problem. Below we break out each issue in detail and explain how to resolve it.

1. Diagnosing and Repairing Boost Leaks

Why Boost Leaks Are Common

The SP Turbo Kit uses silicone couplers and worm-gear clamps to join sections of aluminum intercooler piping. Over time, or if not properly tightened, the couplers can slip or develop small gaps. A boost leak causes the turbo to work harder to reach target pressure, reducing airflow to the engine and making the car run rich. You may notice a loss of power, poor fuel economy, and a hissing sound under acceleration.

Step-by-Step Leak Check

  • Visual inspection – Look for couplers that have shifted off the pipe bead. Check all clamp screws for tightness; tighten to 5–6 Nm (do not over-torque and crush the pipe).
  • Smoke test – Pressurize the intercooler system to 15–20 psi with a commercial smoke machine. Any smoke escaping from joints or the throttle body gasket indicates a leak.
  • Pressure test while listening – If a smoke machine is not available, attach a 20 psi air source to the turbo outlet, plug the throttle body, and spray soapy water on every connection. Bubbles reveal leaks.

Fixing Leaks

Once you locate a leak, replace any damaged coupler or o-ring. Upgrade to T-bolt clamps if the factory worm-gear style repeatedly loosens. For the throttle body elbow, use a high-temp silicone hose with a reinforced inner liner. Many owners also install a MAPerformance boost leak tester kit to simplify future checks.

2. Solving Fuel Delivery Problems

Why Fuel Delivery Becomes an Issue

The stock BRZ fuel system can supply enough fuel for about 280 whp on pump gas. The SP Turbo Kit, when turned up past base boost (typically 7-9 psi), often requires higher flow. Symptoms include lean air-fuel ratios (AFRs above 13.0 under boost), hesitation, or fuel trim values that climb over 25% positive. A lean condition at high load can quickly lead to engine damage.

Troubleshooting Fuel Delivery

  • Verify fuel pressure – Connect a mechanical gauge to the fuel rail test port. Idle should be ~43 psi; under boost pressure should rise 1:1 with manifold pressure. If pressure drops, the pump or regulator is struggling.
  • Check fuel pump wiring – The SP Kit includes a fuel pump rewire harness. Ensure it is connected to a clean 12V source and that the ground is secure. A poor connection reduces voltage and pump output.
  • Inspect fuel lines – After some miles, the rubber factory lines can collapse or kink near the engine bay heat shield. Replace with PTFE-lined or -6AN braided hose for long-term reliability.
  • Test injectors – Flow-match injectors or upgrade to 750–1000cc units if running E85. A clogged injector will show a negative fuel trim on one cylinder.

Fixes and Upgrades

For most SP Kit users running pump gas, a DW200c or AEM 340lph in-tank fuel pump is the first step. Combine with an adjustable fuel pressure regulator set to 43 psi base. If you plan to exceed 400 whp, upgrade to a surge tank and dedicated external pump. Always re-tune after any fuel system change to protect the engine.

3. Resolving Engine Knocking or Pinging

Root Causes of Knock

Detonation (knock) happens when unburned fuel ignites spontaneously in the combustion chamber. The FA20 engine has a high compression ratio (12.5:1 in the BRZ), making it knock-sensitive when turbocharged. Common triggers include low-octane fuel, excessive ignition timing, high intake air temperatures (IATs), or a failing knock sensor.

Diagnostic Steps

  • Fuel octane – Always use 93 octane (or 91 if that is the highest available) when running the SP Kit. If knocking occurs on an ethanol blend, check that your ethanol content matches the tune.
  • Log ignition timing – Use a data logger (ECUTek or Cobb Accessport) to view knock correction values. Negative corrections of -3 degrees or more indicate active knock. Review ignition advance at high load and compare to your tuner's target map.
  • Reduce IATs – The SP Kit intercooler sits in the engine bay heat soak zone. Verify your intercooler is clean and the heat shield around the turbo is installed. Consider wrapping the downpipe and using a cold-air intake duct.
  • Check the knock sensor – Remove and re-torque the knock sensor bolt to 20 Nm. A loose sensor sends false knock signals, causing the ECU to pull timing unnecessarily.

Correcting the Tune

A reliable tuner can adjust the ignition table to eliminate knock while maintaining power. Do not simply add octane booster as a band-aid; the root cause must be addressed. If you are using an off-the-shelf tune, ensure it matches your exact injectors, fuel pump, and boost level. Custom tuning by a specialist like those on FT86Club is strongly recommended for safety.

4. Minimizing Turbo Lag

When The Turbo Fails to Spool

Turbo lag feels like a dead spot from 2500 to 4000 RPM, followed by a sudden surge of power. While some lag is inherent in any turbocharged BRZ, excessive lag points to a specific problem: a too-small exhaust housing, a wastegate that is stuck open, or an exhaust leak before the turbo.

Common Causes and Solutions

  • Wastegate operation – The SP Kit uses an internal wastegate. Check that the actuator rod moves freely and the spring tension holds the flapper closed until boost builds. A loose actuator can bleed pressure early. Use a pressure source to verify cracking pressure (typically 5-7 psi).
  • Exhaust leaks – A leak at the manifold-to-head gasket or the turbo-to-downpipe flange allows exhaust gas to escape before reaching the turbine wheel. Tighten all bolts to the specified torque and use new OEM gaskets if you suspect leakage.
  • Turbo size mismatch – The SP Kit ships with a BorgWarner EFR 6758 or a similar frame. If you have swapped to a larger turbo (e.g., GTX3071), expect increased lag. Conversely, a smaller A/R turbine housing will spool quicker but cap top-end power.
  • Boost control solenoid – A faulty electronic boost controller solenoid can prevent the turbo from building pressure. Test the solenoid with a multimeter and replace if it does not cycle properly.

Practical Fixes

Install a quality boost controller (such as a PTP or McBoost electronic unit) and tune the duty-cycle ramp to spool the turbo earlier. Wrapping the exhaust manifold with titanium heat wrap helps retain exhaust energy, reducing spool time by 200–400 RPM. Some owners also port the wastegate passage to improve flow.

5. Dealing with Excessive Exhaust Smoke

What the Smoke Tells You

White smoke on start-up or under boost typically means oil is leaking into the exhaust system; blue smoke indicates oil burning in the combustion chamber; black smoke is unburned fuel. For the SP Turbo Kit, white smoke is the most concerning, as it often signals a damaged turbo oil seal or a clogged oil return line.

Troubleshooting Oil Leaks in the Turbo

  • Inspect oil return line – The gravity-fed oil drain from the turbo must have a continuous downward slope back to the oil pan. If the line is kinked or restricted, oil backs up into the center housing and pushes past the seals. Remove the line and check for debris.
  • Check turbo shaft play – With the air intake removed, grab the compressor wheel and try to move it side-to-side. Excessive radial play (more than ~1mm) indicates worn bearings. Axial play (in/out) of more than 0.5mm is also a failure sign. Replace the turbo cartridge.
  • PCV system – A clogged PCV valve or crankcase breather can pressurize the crankcase and force oil into the turbo drain. Install a Catch can or PCV delete to reduce oil contamination.
  • Open the downpipe – Probe the turbine outlet with a borescope to check if oil is pooling. If the shaft seal is wet, rebuilding or replacing the turbo is necessary.

Fixing the Source

Replace the turbo oil feed line restrictor (if not already in the kit) to a 0.040-inch orifice to reduce oil pressure to the center cartridge. Use AN -10 line for the drain, the largest diameter that fits. If smoke persists after these repairs, have the turbo professionally rebuilt with upgraded seals.

Installation Pitfalls That Lead to Problems

Many issues traced back to the SP Turbo Kit are not hardware defects but installation oversights. Avoiding these common mistakes will save you hours of rework:

  • Torque specifications – The manifold-to-head nuts must be torqued to 30 ft-lb in sequence. Under-torquing causes a blowout; over-torquing can warp the flange. Use antisieze on the studs.
  • Oil feed line angle – The feed hose should exit the turbo downward to avoid an air lock. If it angles upward, air trapped in the line causes oil starvation on start-up.
  • Grounding the ECU – The SP Kit requires grounding the ECU’s MAF sensor circuit to a clean chassis point. A poor ground leads to erratic idle and fueling issues. Solder the ground wire and seal with heat shrink.
  • Intercooler fitment – The front-mount intercooler must not contact the radiator core. Use rubber isolators or custom brackets to prevent vibration damage over time.

Tuning and ECU Calibration for the SP Turbo Kit

Importance of a Proper Tune

The SP Turbo Kit will not run safely on a bone-stock ECU without a re-tune. Even if the kit comes with a base map, that map is a starting point, not a finished calibration. Every car has slight variations in fuel octane, barometric pressure, and component wear. A custom tune optimizes ignition timing, boost targets, and fuel trims for your specific setup.

What to Look for in a Tune

  • Fuel mapping – Target AFRs at full boost should be between 11.0 and 11.8 for pump gas. For E85, aim for 11.5–12.2.
  • Boost curve – A safe boost taper (e.g., 14 psi at peak torque falling to 12 psi at redline) reduces the risk of detonation.
  • VE (volumetric efficiency) tables – Ensure the tuner adjusts the MAF scaling to compensate for your intake and intercooler.
  • Cold start and idle – The FA20’s direct injection can cause rich misfires at low coolant temps. A good tune includes a revised cranking and warm-up fuel table.

Tuning Platforms

The most popular tuning solutions for the BRZ are Cobb Accessport (with open-source mapping via EcuFlash) and ECUTek. Both allow real-time logging and remote calibration. If you are not a DIY tuner, hire a professional with FA20 experience. For a list of recommended tuners, check the SP Turbo Kit vendor’s official support forum.

Preventive Maintenance for Long-Term Reliability

Prevention is far less expensive than rebuilding a damaged engine. Follow this maintenance schedule to keep the SP Turbo Kit performing at its best:

  • Engine oil – Change every 3,000 miles (4,800 km) using a high-quality 5W-30 synthetic such as Motul 8100 or Liqui Moly. Avoid used engine oil additives.
  • Turbo oil feed – Inspect the feed line for cracks or swelling at each oil change. Replace if any abrasion is visible.
  • Intercooler cleaning – Every 10,000 miles, remove the intercooler and flush with mineral spirits to remove oil residue that reduces cooling efficiency.
  • Boost leak check – Perform a pressure check every 6 months or whenever you feel a power drop. Replace any brittle vacuum lines.
  • Spark plugs – The FA20’s iridium plugs should be replaced every 15,000 miles when boosted. Use colder heat range plugs (Denso IKH24 or NGK LFR7AIX) to prevent pre-ignition.
  • Coolant system – Flush the coolant annually (or replace with Evans waterless coolant) to prevent electrolysis damage to the heater core and radiator.

Conclusion

The SP Turbo Kit transforms the Subaru BRZ into a genuinely fast sports car, but it demands respect for its installation and maintenance requirements. Boost leaks, fuel delivery shortfalls, knock, lag, and oil smoke are all solvable when approached with logical diagnostics and the right parts. By carefully inspecting your kit at each service interval, investing in a quality tune, and addressing problems at the first sign, you can enjoy years of reliable forced-induction performance. For more detailed discussions and build logs, the BRZ community on FT86Club remains the best resource for real-world troubleshooting. Keep your boost steady and your AFRs safe, and the SP Turbo Kit will reward you with a thoroughly addictive driving experience.