After the rebuild came the OEM+ tune up.

 turbo. 

Months of pampering had finally come to their climax—the break-in period had been reached, and the TT was finally ready for its tune-up. However, this was not going to be your usual filter-and-plugs ordeal, not in the slightest.

I had spent weeks, if not months, researching the known weak points of the EA888.2 engine and made it my mission to ensure they were addressed. The first was the consistently problematic positive crankcase ventilation (PCV) plate integrated into the aluminum valve cover.

This emissions system is designed to route gases that enter the crankcase back into the intake stream to be reburned in the combustion chamber. However, it is prone to failure, often without warning, allowing oil to enter the intake tract and contribute to carbon buildup on the intake valves.

This issue was addressed by installing a CTS Turbo CNC aluminum PCV replacement plate, paired with an oil condenser and catch can. Oil vapor travels from the CNC plate into the catch can, which uses a ten-plate baffling system. As the heated gases pass through the can, they condense, separating oil from vapor before routing back through the CNC plate and into the turbo inlet.

This setup helps reduce further carbon buildup on the intake valves and improves upon the factory emissions routing system by allowing the engine to operate more efficiently.

The coil packs were also known to fail and cause misfires. A common upgrade is the installation of Audi R8 red-top coil packs, which provide a stronger, more reliable spark and improved connectivity. The factory spark plugs were replaced with NGK Iridium Hyper Extreme plugs, offering a more consistent and aggressive spark profile.

Although the engine produced respectable torque on its relatively conservative OEM tune, there was still noticeable drivetrain slop from the torque arm and soft factory bushings. To address this, a CTS Turbo dogbone mount insert was paired with a CNC torque arm upgrade featuring polyurethane bushings, improving responsiveness by reducing unwanted movement.

The EA888.2 also suffers from restrictive intercooler piping. Tube diameters change abruptly with sharp bends that are detrimental to airflow. Imagine trying to push a large volume of air through a narrow straw—then adding multiple sharp bends and kinks. That’s an accurate representation of how restrictive the factory setup is, particularly for a small turbo designed for quick boost response.

To resolve this, multiple components were installed to create a more efficient charge piping system. A CTS Turbo “turbo muffler delete” was paired with larger K04 charge pipes. Gone are the restrictive bends that created turbulent airflow and placed unnecessary stress on the already small K03 turbo.

The stock diverter valve, which is also prone to wear and failure, was upgraded with a CNC aluminum piston-style core and paired with a vent-to-atmosphere spacer. The intent of the VTA setup is to reduce compressor surge and prevent turbulent air during throttle lift-off.

Since the engine had recently been rebuilt, a magnetic oil drain plug was also added to provide insight into any residual metallic debris circulating in the oil system. While not a traditional weak point, it serves as a useful diagnostic upgrade.

Finally, the factory airbox and intake were replaced with a performance cold air intake designed to reduce restriction while maintaining cool, clean airflow to the turbo.

The concept behind the entire tune-up was simple: reduce restriction so the turbo can breathe more freely. In turn, the engine becomes more efficient across the board. Gains in performance, fuel economy, and reliability are further enhanced when paired with a software tune. As boost pressure increases, restrictions become more significant—but so do the performance gains.

Some modifications improve not just performance, but also the quality, reliability, and drivability of the vehicle without turning it into an over-the-top “Fast and Furious” build.

So far, the tune-up has made a noticeable difference in responsiveness, performance, and fuel economy. As time goes on, there will be opportunities to further refine and upgrade OEM components.

Until then, I’ll be enjoying the improved TT and logging its enhanced performance whenever possible.

Stay tuned.