Is Your 2020 Subaru WRX Tune Causing Problems?

How to Fix Tune Issues

Experiencing performance problems with your 2020 Subaru WRX after a tune? You're not alone. Many owners encounter issues related to fuel delivery or intake leaks after modifying their vehicle. As one owner stated, "My problem is that this seems to affect the pressure in my heater core to such an extreme that now it doesn’t blow hot when my car is idling." While this specific quote refers to a cooling mod, the underlying concept of modifications affecting other systems is relevant to tuning issues. This guide will walk you through common symptoms, diagnostics, and potential fixes based on reported experiences from other 2020 Subaru WRX owners.

Symptoms

Aftermarket tunes can sometimes cause a range of symptoms in your 2020 Subaru WRX. Owners have reported issues like excessive popping from the exhaust, which can indicate an improper fuel mixture. You might also notice black smoke emanating from the tailpipe, especially during acceleration. This symptom often points to the engine running too rich, meaning there's an excess of fuel compared to air in the combustion chamber.

Another common complaint is engine backfires. Backfires typically occur when unburnt fuel ignites in the exhaust system, creating a loud bang and potentially damaging exhaust components. Stalling is also a symptom that can indicate a problem with the tune. "Either put back the stock intake or upgrade other parts of the car so it runs better. Its not worth spending 8-900$ for a tune just for an intake lmfao," cautioned one owner. This highlights that some tunes, especially those done poorly or without proper supporting modifications, can lead to drivability problems.

Experiencing any of these symptoms after a tune is a sign that something is not right. It's crucial to address these issues promptly to prevent potential damage to your engine and other components. Pay attention to when these symptoms occur – is it during specific driving conditions, like idling, acceleration, or deceleration? Gathering this information will be helpful when troubleshooting the underlying cause.

Most Likely Cause

Based on owner reports, a primary cause of tune-related problems in the 2020 Subaru WRX is the fuel system. Improper tuning can disrupt the delicate balance of the air-fuel mixture, leading to a range of issues. A tune designed for specific modifications might not work correctly if those modifications aren't properly installed, or if there are underlying issues with the fuel injectors, fuel pump, or fuel pressure regulator. Furthermore, modifications to the intake system without proper tuning can also cause significant issues.

In some cases, the fuel system itself may not be the problem, but rather the tune is not properly calibrated for the specific hardware in your vehicle. As one owner indicated, "Getting a tune with only an air intake is just wild to me lol. Either put back the stock intake or upgrade other parts of the car so it runs better." This highlights that a proper tune needs to take into account any modifications made to the engine, intake, or exhaust systems.

How to Diagnose

Diagnosing tune-related issues in your 2020 Subaru WRX requires a systematic approach. Here's a step-by-step process you can follow:

1. Visual Inspection: Start by visually inspecting all hoses and connections related to the intake and fuel system. Look for any cracks, leaks, or loose connections that could be causing a vacuum leak or fuel leak. Pay close attention to the intake manifold, fuel injectors, and fuel lines.
2. Data Logging: If you have an Accessport or other diagnostic tool, use it to log engine parameters such as air-fuel ratio (AFR), fuel trims, and boost pressure. Analyze the data to see if there are any anomalies or deviations from the expected values.
3. Boost Leak Test: Perform a boost leak test to check for any leaks in the intake system. This can be done using a boost leak tester, which pressurizes the intake system to identify any leaks. Listen for hissing sounds or use soapy water to pinpoint the source of the leak.
4. Fuel Pressure Test: Use a fuel pressure gauge to measure the fuel pressure at the fuel rail. Compare the reading to the factory specifications to ensure that the fuel pump is delivering adequate fuel pressure.
5. Check for Codes: Even if the check engine light isn't on, use an OBDII scanner to check for any stored diagnostic trouble codes (DTCs). These codes can provide valuable clues about the underlying problem.
6. Consult Your Tuner: Reach out to the tuner who created the tune for your vehicle. They may be able to provide insights based on the data logs you collected and offer suggestions for troubleshooting the issue.

Tool Requirements:

• OBDII scanner
• Accessport or other diagnostic tool (optional)
• Boost leak tester
• Fuel pressure gauge
• Basic hand tools (screwdrivers, wrenches, etc.)

Step-by-Step Fix

Based on owner reports, addressing fuel system issues related to tuning on your 2020 Subaru WRX often involves the following steps:

1. Revert to Stock Tune: If you suspect the tune is the problem, revert back to the stock tune. This will help you determine if the issue is related to the aftermarket tune or if there is an underlying mechanical problem.
2. Address Intake Leaks: If you suspect an intake leak, carefully inspect all hoses and connections for cracks, leaks, or loose fittings. Replace any damaged components and ensure all connections are secure.
3. Verify Fuel Injector Function: Check the fuel injectors to ensure they are functioning correctly. You can use a multimeter to measure the resistance of the injectors and compare the readings to the factory specifications. If an injector is faulty, replace it.
4. Check Fuel Pressure: Verify the fuel pressure at the fuel rail using a fuel pressure gauge. If the fuel pressure is low, check the fuel filter for clogs and replace it if necessary. You may also need to inspect the fuel pump to ensure it's delivering adequate fuel pressure.
5. Data Log and Refine Tune: If the issue persists after addressing any mechanical problems, work with your tuner to refine the tune. Provide them with detailed data logs of your engine parameters so they can make the necessary adjustments to the fuel maps.
6. Consider Supporting Mods: As one owner pointed out, upgrading other parts may be needed for the tune to work correctly. Adding an intake requires a tune adjusted for the greater airflow. Evaluate adding supporting modifications if you are experiencing issues.
7. Professional Retune: If you are not comfortable with tuning the vehicle yourself, seek professional help from a reputable tuner. They can properly diagnose the issue and make the necessary adjustments to the tune to ensure optimal performance and reliability. As one owner shared: "I was tuned by DMann before going ethanol, and after installing my Cobb CAN gateway FlexFuel kit I used Cobb’s map."

Parts and Tools Needed

• Replacement hoses and clamps (if intake leaks are found)
• Fuel injectors (if faulty)
• Fuel filter (Subaru Part Number: 42072FA120)
• Fuel pump (if necessary)
• OBDII scanner
• Accessport or other diagnostic tool (optional)
• Boost leak tester
• Fuel pressure gauge
• Basic hand tools (screwdrivers, wrenches, etc.)

Real Owner Costs

The cost of fixing tune-related issues on your 2020 Subaru WRX can vary widely depending on the nature of the problem. Here are some examples based on real owner experiences:

• DIY Intake Leak Repair: Replacing a cracked intake hose and clamps can cost around $50-$100 in parts.
• Fuel Injector Replacement: Replacing a set of fuel injectors can cost anywhere from $200-$500, depending on the brand and flow rate.
• Fuel Pump Replacement: Replacing the fuel pump can cost around $300-$600, including the cost of the pump and labor.
• Professional Retune: A professional retune can cost anywhere from $500-$1000, depending on the tuner's experience and the complexity of the tune.
• As one owner mentioned it may not be "worth spending 8-900$ for a tune just for an intake". If adding supporting mods, the total cost can be much higher.

DIY vs. Shop Comparison:

• DIY: Doing the repairs yourself can save you money on labor costs, but it requires mechanical knowledge and the right tools.
• Shop: Taking your vehicle to a professional mechanic or tuner can ensure the job is done correctly, but it will cost more in labor. If you're not comfortable working on your vehicle, it's best to seek professional help.

Prevention

Preventing tune-related issues on your 2020 Subaru WRX involves taking proactive steps to ensure proper installation and maintenance of your aftermarket tune.

• Choose a Reputable Tuner: Select a tuner with experience tuning Subaru vehicles. A skilled tuner will be able to properly calibrate the tune for your specific modifications and driving conditions.
• Proper Installation: Ensure all modifications are installed correctly and according to the manufacturer's instructions. This includes properly sealing all connections and verifying proper functionality.
• Regular Maintenance: Perform regular maintenance on your vehicle, including oil changes, filter replacements, and spark plug replacements. This will help ensure that your engine is running optimally and prevent potential problems. As one owner shared: "I go every 5k using Pennzoil Platinum 5w-30, though it's just a stock engine/tune and more than half are highway miles".
• Data Logging: Regularly data log your engine parameters and review the data for any anomalies or deviations from the expected values. This can help you catch potential problems early before they escalate.
• Monitor Fuel Quality: Use high-quality fuel from reputable gas stations. Low-quality fuel can cause engine knocking and other problems that can affect the tune.

What Owners Say

Real experiences from SUBARU owners:

Owner Experiences

"The mod increases flow which is great, but as such it decreases pressure (I have the RCM variant of the kit) My problem is that this seems to affect the pressure in my heater core to such an extreme that now it doesn’t blow hot when my car is idling." — omv_owen (source)

"My problem is that this seems to affect the pressure in my heater core to such an extreme that now it doesn’t blow hot when my car is idling. Mind you it still does get hot when I’m driving and my coolant never gets too hot under any circumstances. (I have an AP and am pro-tuned in a forged build)" — omv_owen (source)

"Either put back the stock intake or upgrade other parts of the car so it runs better. Its not worth spending 8-900$ for a tune just for an intake lmfao." — YoungsterGk (source)

Pro Tips from Owners

💡 "If you come across a time where you want to ask if you should get a tune before installing something else, the answer is yes, always get a tune." — sompn_outta_nuthin (source)

💡 "-when shopping used, go over the Carfax with a fine-tooth comb. There are some key services every 30k miles, especially at 60 & 120k, and make sure to read accident history." — gingysaurusrexx (source)

Real Repair Costs

"So my local tuner charge $1.6k for two dynos for FlexFuel. I honestly can’t afford that." — Aware-Requirement-67 (source)

"I brought him down from $15.5k a couple months ago to under $10k cash to finally buy it. Interior is already all back in and working, full detail inside and out, ordered a voltex front lip that will cover all damages on the bumper/grill area, dual A pillar gauge pod, new gauges that actually work, the center long dash trim, and will be eventually getting a new hood, trunk, and some pdr on the roof to get rid of hail damage come spring time." — SupremePribs (source)

"It ended up being a solid ass buy. I brought him down from $15.5k a couple months ago to under $10k cash to finally buy it." — SupremePribs (source)

FAQ

Q: How long does it take to fix tune issues?

A: The time it takes to fix tune issues varies greatly depending on the specific problem. A simple intake leak repair might take an hour or two, while a more complex issue like a faulty fuel injector or a retune could take several hours or even days.

Q: Can I drive with tune issues?

A: It's generally not recommended to drive with tune issues, especially if you're experiencing symptoms like stalling, backfiring, or excessive smoke. These symptoms can indicate a serious problem that could potentially damage your engine.

Q: Is this a common issue on the 2020 Subaru WRX?

A: Tune-related issues are relatively common on modified 2020 Subaru WRX vehicles. Anytime you deviate from the factory settings, there's a risk of encountering problems. However, with proper tuning and maintenance, you can minimize the risk.

Q: DIY vs mechanic - what's recommended?

A: Whether you should attempt to fix tune issues yourself or take your vehicle to a mechanic depends on your mechanical skills and comfort level. If you're comfortable working on your vehicle and have the necessary tools, you may be able to tackle some of the simpler repairs yourself. However, if you're not confident in your abilities, it's best to seek professional help from a qualified mechanic or tuner.