OBD Analysis After Removing Airbox Intake Grid Rezonator (5Q0129668F) — Test & Observations

[AlperUtkuCeylan]

My car: | 41AC676 | 2021 Seat Ibiza 1.0 EcoTSI DSG (engine code DLAA, 110 HP / 200 Nm, DQ200 gearbox).
After removing the hood insulation, I wanted to hear more engine sound.
For this reason, I removed the grid-like plastic piece inside the airbox (part number: 5Q0129668F), which sits before the air filter and directs the airflow.

Test conditions:​

• City driving in Istanbul (traffic, stop&go) + some light aggressive throttle.
• OBD parameters monitored:
  • STFT (Short Term Fuel Trim)
  • LTFT (Long Term Fuel Trim)
  • IAT (Intake Air Temperature)
  • Boost & Throttle
  • Coolant temp

Observations:​

• STFT mostly ±0–3%, with short spikes up to +10–20% → pretty normal.
• LTFT steady between −2 and −0.8% → healthy long-term adaptation.
• IAT ambient 21 °C, but stayed 40–48 °C in traffic → normal, but could rise more in summer. (Even though it looks healthy now, the vehicle is reaching these temperatures due to its own engine bay structure and it also shows that there is still some room for improvement for me. In the future, I will also make improvements related to the airflow or the intercooler.)
• Coolant average 93 °C → normal.
• Sound: Slightly more intake hiss and turbo whoosh noticeable inside the cabin.
• Performance / fuel economy: No measurable difference, fuel consumption remained the same.

Conclusion:​

• Removing this part did not negatively affect engine health; trims and temps remain within normal healthy range.
• Only NVH changed: intake sound is sportier, which some may like.
• For long-term use, proper maintenance is key (I service every 10k km and check the filter regularly).

 

[Syphon]

Very cool thanks for sharing

 

[AlperUtkuCeylan]

Very cool thanks for sharing

Thanks

 

[AlperUtkuCeylan]

To evaluate the effects of two small modifications on my car's engine, I captured two separate data logs with my 41 AC 676 plate, 2021 SEAT Ibiza 1.0 EcoTSI (DLAA, 110 HP / 200 Nm) equipped with a DSG DQ200 transmission. The first log covers an urban stop-and-go drive, while the second one is from a calm highway cruise. The modifications I made were:

1. The air filter box resonator (part code: 5Q0129668F) was removed.
2. The flap on the air intake duct behind the grille was temporarily sealed with tape.

I am sharing the results obtained from the analysis of the log data with you.

Technical Evaluation with Log Data​

• Fuel Management (Fuel Trims): One of the most crucial data points, the LTFT (Long Term Fuel Trim), was measured as a constant 0% in both logs. This indicates that the modifications did not permanently disrupt the air-fuel ratio, and the engine is operating in perfect harmony with its original factory settings. During the city drive, the STFT (Short Term Fuel Trim) briefly spiked to +7.81% but generally stayed within the ±3% range. These values are completely normal.
• Temperature Values: Assuming an ambient temperature of 20°C, during the fully warmed-up highway drive, the engine oil temperature increased from 85°C to 103°C, and the engine coolant temperature rose from 96°C to 101°C. These values prove that the cooling system is operating perfectly. The Intake Air Temperature (IAT) remained between 33-41°C, while the Charge Air Cooler (CAC) outlet temperature was in the 38-47°C range. These values show that the modifications did not cause hotter air to enter the engine.
• Performance Data: The maximum turbo boost pressure (MAP) was recorded as 1.14 bar in the city log and 1.48 bar in the highway log. These figures demonstrate that the turbocharger can easily produce the required pressure despite the car having 85,000 km on the clock. The Timing Advance values stayed consistently positive (+2° to +22°) in the highway log, indicating that the engine experienced no knocking.
• Transmission Health (DQ200): Clutch 1 and 2 temperatures reached a maximum of 90°C in both logs. This is a normal temperature range for the DQ200's heat management.

Conclusion and Takeaways

Based on the OBD log data, the modifications I made have not had any negative impact on the engine's health. The air-fuel ratio remains stable, temperatures are within the normal range, and the engine continues to operate efficiently without any knocking. The only noticeable difference is that the engine's intake and turbo sounds have become more prominent inside the cabin. This adds a more aggressive, sporty character to the car's NVH (noise, vibration, harshness).