05/10/2026
This MK8 Ford Fiesta ST 1.5 EcoBoost came to us with an underboost fault that several local garages, including a Ford dealer, had been unable to diagnose.
The customer had recently bought the car and was told the original turbo’s wastegate was worn. He purchased one of our Turbo Technics exchange turbos, but the fault remained. We explained that the old turbo was clearly worn and suggested there could be another issue, such as a boost leak.
After further attempts elsewhere, the car had been fitted with several parts, including an AIRTEC intercooler, vacuum pump and boost solenoid, but the underboost fault was still there.
We carried out data logging and a thorough inspection at OC Motorsport, where we found two significant boost leaks. Once repaired, we logged the car again and confirmed the issue was fixed. The difference in performance was night and day.
The customer also chose to have our Peak Performance Stage 1 calibration added. It transformed the car’s performance and optimised the air-fuel ratios for a turbocharged petrol engine. We’ve seen over 250bhp from this calibration, so it makes a serious difference to the three-cylinder 1.5 EcoBoost.
This is a good example of why choosing a specialist who knows your car can save time, money and unnecessary parts.
