DeatschWerks DW400 In-Tank Fuel Pump; w/ 9-1047 Install Kit

Proper maintenance is key to ensuring your vehicle runs safely, reliably, and performs at its best with your custom tune.

We recommend staying on top of the following items, specifically:

• Engine oil: Check regularly and run ~0.5 quart over (especially if launching or driving aggressively)

• Service intervals: Shorten intervals and stay ahead of routine maintenance

• Fluids: Check levels consistently and adjust as needed (engine, trans, etc.)

Remember:

• Tuning can’t fix mechanical issues

• Mechanical issues won’t always show in logs

• Overall vehicle condition directly impacts performance

For full details, please refer to our Maintenance & Fill Recommendations guide. Your tune file notes and any direct guidance from our team always take precedence.

Additional Considerations:

Spark Plugs & Ignition Health

Maintain properly gapped, quality spark plugs and ensure ignition components are in good condition—this becomes increasingly important on higher-power setups. We recommend the NGK 95605:

Overall Vehicle Health

Address any underlying issues promptly, as the tune is designed around a properly functioning vehicle

Hardware Changes

If you plan to modify or install additional parts, we recommend reaching out before aggressive driving so we can confirm compatibility with your current calibration

For additional detail, we provide a Maintenance & Fill Recommendations guide as a reference.

Please note: Your tune file notes and any direct guidance from our team will always take precedence.

Before making any hardware changes, we recommend reaching out so we can review your setup and confirm compatibility with your current tune.

Your calibration is built around your existing configuration, and even small changes can impact performance, drivability, or reliability. Getting ahead of this ensures your vehicle continues to operate as intended.

If updates are needed, we’ll guide you through the next steps before you push the vehicle.

If something doesn’t feel quite right, stop driving aggressively and reach out to our team so we can take a closer look.

📋 Letting us know what you’re experiencing—along with any recent changes or conditions—helps us determine next steps quickly.

📈 In many cases, we may request a data log to review what’s happening.

⚠️ Including full DTC reports or relevant screenshots, photos or videos with your request is helpful to us and can reduce the time required for troubleshooting.

⚙️ For transmission-related concerns (e.g., harsh or inconsistent shifting), please see this FAQ: Why is my transmission shifting harsh after tuning?

📌 Please keep in mind:

• Tuning can’t resolve underlying mechanical issues

• Not all mechanical issues will show clearly in data logs

• Overall vehicle condition plays a direct role in performance

We’re here to help—reach out and we’ll work with you to get things sorted.

Harsh or inconsistent shifting immediately after a tune is not uncommon and is typically not a concern.

Modern Ford transmissions use adaptive learning, meaning the transmission adjusts shift behavior based on driving habits over time.

What to expect:

• Adaptive learning is reset any time the ECU is flashed

• Initial driving may feel inconsistent or harsh while the system re-learns

• Heavy throttle / WOT-focused driving early on can delay smooth behavior

• Adaptation is drive-mode specific, so behavior may vary between modes

• This relearning process can take several drive cycles depending on driving conditions

In most cases, normal mixed driving will resolve shifting behavior as the transmission relearns.

⚠️ When to take action

If concerns persist after adequate driving/adaptation, or if you have immediate concerns, follow this process:

• ✅ Check transmission fluid level

• ✅ Perform a re-learn cycle

• ✅ Capture a data log of the concern

• ✅ Flash back to stock to isolate behavior (if needed)

📎 Transmission Guide (PDF) includes full step-by-step instructions:

• Fluid level verification

• Re-learn procedure

• Logging + next steps

🧠 Important reminders

• Tuning cannot fix mechanical issues

• Some mechanical issues may not appear in logs

• Transmission behavior is heavily influenced by adaptive learning

To ensure your vehicle performs as intended, it’s important to consistently run the specific fuel type your tune was designed for. The fuel type of your tune is in the file name and can be reviewed in the TDN App at any time.

Using lower-octane or inconsistent fuel can impact performance, drivability, and overall reliability.

If you’re considering changing fuel types (e.g., switching octanes or moving to an ethanol blend), you can purchase an Additional Tune to cover it.

Don't hesitate to reach out first so we can confirm compatibility or advise on next steps.

💡 For more information on Fuel and Ethanol Blends, please see the Fuel & Gains section of our FAQ.