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2014 Ford Fiesta ST project

44079 Views 126 Replies 27 Participants Last post by  twendt
So I picked up a 2014 Ford Fiesta ST to play with. There are a bunch of reasons I did this so I'll just make a simple numbered list to help explain why.

1. I wanted a small lightweight car again (It's 27XXlbs)
2. I wanted to learn the Ford ECU
3. I wanted to track a small lightweight car
4. I wanted a small lightweight car that got great gas mileage for my commute

That's about it overall for the reasons. With over 20 years of driving Mitsubishis, Subarus and VW's I never ever ever ever thought I would own a Ford....

For some reason the Focus ST never really intrigued me. After reading all the press about the Fiesta ST, it did intrigue me, I went and test drove a bunch and I totally fell in love with the car. It really feels like something special, a Ford engineering baby.

I still own my current Evo, an Evo 10, for now. It's in a different league for sure, but I didn't buy the Fiesta ST to replace the Evo. So enough about that.

This thread will serve as a place to post my findings as I learn the car, the ECU, etc.

I come from a tuning background. I used to tune Mitsubishis professionally, mainly Evos. Most recently a 2005 Evo 8 MR for 10 years that was my personal project, that I tuned and tracked. It had 500hp on E85. I also had a 2010 Mitsubishi Lancer Sportback Ralliart that I also tweaked and tuned to 400hp on E85. As stated above still have my Evo 10, 400hp, also on E85. You can sense what's coming for the Fiesta ST then.

Initial photos, 100% stock minus upgraded wheels/tires.

2014 Ford Fiesta ST
Recaro Package
"Rado" wheel package (painted wheels and brake calipers)

Wheels replaced with Sparco Assetto Gara 17x7 +42 satin black
Tire replaced with Bridgestone Potenza S-04 205/45/17

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I have a question for you, in STx autocross classes, tunes are an allowed modification. However, the tune cannot alter "boost controls". Is there a way to tune the ecu for reasonable power gains and leave the boost controls untouched, or is the system so complex that most changes will alter boost. . For example, does changing the torque target also change the boost map? Thanks for your insights, cool to hear about somebody digging into this.
Yep, after 80+ autocross runs and 11k miles, my oem pads still have plenty of life left.
Whole bunch of updates!!!


I almost killed myself and the car at Thunderhill. Second lap into the second session, at 110 mph in the front straight into the braking zone I lost all brakes and had a serious OHHHH FUUUUUU moment.

Lesson learned, Wilwood BP-20's have no business being on a car that is on track. They melted and smeared all over the rotors.

Pedal going to the floor at the end of the front straight....

Man that seriously sucked.

I had a set of wilwood BP-30 race pads that I put on after the incident. I SHOULD have done that before the first session but silly me thought I would be ok the first two sessions getting used to the car but the BP-20's had a different idea. The brakes where rock solid after I put the race pads in. Bone headed move on my part. I know better.

Obligatory track paddock photo:

Playdoh melted BP-20 pads smeared all over my rotors

Since I am a data junky, I was really looking forward to datalogging at the track today. I have 5 sessions worth of datalogs to comb over but here is the first interesting one.

This is a datalog of my last session of the day in the afternoon. About four full laps of a 2.8 mile course. It was about 95* ambient at the time. The hottest session.

My selection is over the peak numbers for the datalog while on track.

Couple things to note:

1. Correlation between Charge Temp and Coolant temp, the plots almost mirror each other. We really need a upgraded radiator option!
2. Intake temp. How rock steady is that mofo? Stock intake down to the paper filter. Guess it works well.
3. Zero knock except a single 1 blip. Guess my track tune is working. ;)
4. Oil temps. Getting toasty. From what I know from tracking Evos, cooler oil temps will also equal cooler water temps.

More data!

One thing this will show is that I was driving the car at about maybe 70% and I'm sure all the guys I was pointing by can attest to that. ;) It was more of a test and tune day for me since I hadn't been to the track in six years and this is a totally different platform for me, as I am used to high horsepower AWD Evos.

Some of the things I learned was that I have a ton of cobwebs to get out and these little short wheel base FWD cars are hard to drive on track, at least compared to what I am used to!

Btw, an old Evo friend of mine was with me at the track in his Focus ST with cobb stage 1 map. I would easily pull on him in the fast parts of the track based on pure acceleration. Was interesting to see that.

This is my last lap of the day with Lateral G-Force and MPH. Very cool data!

Peak lateral G of .99 in this data set. Like I said I was driving at probably 70% so I think it easily has over 1.0 G in it. I believe a stock FiST has been tested at .92? It also has more mph in at at the end of the front straight, I let off a bit as you can see here. I know when I looked at it right before my braking incident I was at 110 mph but of course my eye to brain connection can be off. ;) If I remember correctly (It's been a long time) my Evo 8 would hit about 125 or so in the same place.

Purple is MPH
White is Lateral G
Positive numbers are left turns and the negative are right turns. So a -.81 would be a right turn at .81g

I was also pretty happy that I could fit almost everything for the track in the back, with the false floor and spare removed. Especially happy how well the two fuel jugs fit. The only thing I couldn't fit is my plastic bin of essentials. Which I put in the back seat.

I have my tool box, a jack stand, a jack, two 5 gallon VP racing fuel jugs and my folding chair in there.

How are you determining the oil temp? Are you getting that through OBD or do you have a dedicated sensor?
Do you know the PID that the system uses to output the signal? Would love to have access to oil temp. Pressure would be better, but beggars can't be choosers.
I knew it wouldn't be that easy. Thanks anyway!
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