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GR Yaris Tuning, Fault Diagnosis & Hybrid Turbo Upgrade

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This Toyota GR Yaris came into Whifbitz for a routine service and ECU tuning, but before moving on to performance work, an underlying issue needed addressing.

Fault Diagnosis & Repair

The owner reported what they believed to be a misfire, something we’ve seen before on GR Yaris models. After inspection and testing, the issue was traced to the ignition system. A new set of genuine Toyota ignition coils resolved the problem immediately, restoring smooth and consistent engine operation.

With the fault rectified, the car then received a full service, ensuring it was in the best possible condition before performance tuning began.

Existing Modifications

The GR Yaris already had a strong foundation in place, featuring several upgrades we regularly recommend:

  • Whifbitz exhaust system
  • GPF delete pipe
  • Eventuri intake kit
  • Airtec intercooler

In addition to the power-related upgrades, the car also featured a number of chassis, interior, and styling enhancements:

  • SW Motorsport rear cage with rear seat delete
  • Coolerworx short shifter
  • Toms Racing rear bumper vents
  • Whifbitz TM-style rear spoiler
  • Turbosmart dual-port blow-off valve
  • Whifbitz bonnet damper kit

These modifications improve driver engagement, weight reduction, cooling, and overall aesthetics.

Performance Upgrades & ECU Calibration

To take the car further, we carried out the following upgrades:

  • Kelford 267A cams & valve springs
  • Midland hybrid turbo
  • Ecutek ECU remap

All calibration work was completed on 99RON pump fuel, with a focus on safe, repeatable power and strong drivability.

Dyno Results

The GR Yaris was configured with low and high boost maps, allowing flexibility depending on driving conditions.

Final dyno results:

  • Low boost: 255whp / 308bhp
  • High boost: 297whp / 357bhp

The result is a sharp, responsive GR Yaris with strong mid-range performance and a healthy increase in top-end power, while remaining well suited to road use.

Final Notes

This build highlights the importance of proper fault diagnosis and preparation before tuning, as well as the effectiveness of combining proven supporting modifications with a well-matched hybrid turbo and custom ECU calibration.

If you’re looking to have your GR Yaris serviced, diagnosed, tuned or upgraded, get in touch with Whifbitz to discuss your project.

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