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Ford Fiesta ST 1.5 Ecoboost Tuning


The old Fiesta ST was a phenomenal success for Ford and a car we like very much here at Bluespark, so the new one had a lot to live up to. 

We appreciate that there are a huge range plug in units and remaps available for Fiesta ST tuning, so we wanted to share a little of our development process to show what we look into.

We had the pleasure of a visit from a returning customer with his brand new ST. We got to work and spent the day datalogging the car, finding its limitations and improving performance.

We strapped the car to our dyno for a couple of runs as standard. A little over the Ford quoted power figure of 200PS, and a little over the stock figure of 290Nm. 

This car was running 99RON fuel, so it is pretty common to see slightly stronger than stock figures.

Ford Fiesta ST Stock Power Dyno Graph

Looking at the stock graph we can see that stock torque looks like an extremely flat line, as does peak power. Almost always when you find results like this there is some software control holding the engine back to make exactly the figures the manufacturer is looking for. First we had a look at stock boost pressure across the whole rev range:

Fiesta ST Stock Throttle Closures Dyno

As you can see, boost pressure has no overshoot spike at the bottom end, and tails off with increasing RPM from 5000RPM onwards. The next place that we look is throttle position:

Fiesta ST Stock Throttle Closures Dyno

Bingo. The dashed line above shows throttle position, with the smooth line showing power. Despite my foot being flat on the pedal, the car is shutting its throttle very significantly at two points in the rev range. As the car comes on boost at 2000RPM up to around 3500RPM, and then from around 4700RPM right the way up to redline. This is a pretty common strategy of many modern ECU's. Throttle closure is a very fast acting way of regulating manifold pressure, but particularly at the top end, the car is very deliberately being held back.

We fitted our tuning system and started working on a file for the car:

Fiesta ST 1.5 Early Stage Tune

After a couple of edits we made a file that eliminated the throttle closure at the top of the rev-range, giving 233hp at peak. If we take a look at the throttle opening (dashed lines) where the stock run has a big throttle closure at the top end, the tuned version has now eliminated this. Tuned torque is improved, but nowhere near what we would like it to be. We can still see that at the bottom end of the rev range (left hand side of the graph) the throttle closure is improved, yet not eliminated.

Working on the file for a little longer we are able to improve on this very significantly:

Fiesta ST 1.5 Throttle Finished Tune

As you can see, the unwanted throttle closures have been eliminated throughout the rev range, allowing the car to make significantly more power and torque.

In the following graph you can see power and torque plotted vs the car as standard: 

Ford Fiesta ST Tuned Dyno Graph

There is a healthy improvement in power and torque throughout the rev-range, with strong gains in torque from low-rpm, maintained right up to redline. As you can see the power curve is also significantly smoother than stock.

To finish up we double check that everything is as it should be in terms of air fuel ratio, trims, and fuel pressure throughout the rev range. Just as an example, here is the Air Fuel Ratio plot vs Stock:

Ford Fiesta ST AFR Dyno Graph

As you can see, the standard target air fuel ratio (solid line) is maintained throughout the rev range.

Finally we take the car out for a road test and ensure that it drives as it should, with smooth power delivery throughout the rev range.

The car is much livelier vs stock, pick up is better and it pushes on much more eagerly. 

The final results are very close to those offered by many flash tunes, but with the advantage that our unit can be tracelessly removed in under 5 minutes (Install Video Here)

Our unit can also be reprogrammed for only £60.00 should you change vehicle in the future.

If you are interested in what we could do for your Fiesta, please take a look at the relevant link below or our Ford Tuning page: 

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ID Make Model Fuel System Engine Size (cc) KW Power (PS/HP) Nm
66416 Ford Ford Fiesta 1.5 TDCi 95PS Common Rail 1499 70 95 215 Select Vehicle
69546 Ford Fiesta 1.5 ST 200 PS Petrol Turbo 1498 150 200 290 Select Vehicle