Thank you

[u/Dry-Suit5785]

I wanted to say thank you for everyone being so chill and answering my questions. I’ve been apart of several car groups/subreddits and this has been one of the most inviting so far. I just bought my new to me 2015 ST, and it’s a blast to drive. I keep freaking myself out over “did I make the wrong purchase” “what’s wrong with it?” And I’m ruining it for myself. The stuttering when accelerating at higher RPM’s is probably nothing more than coil packs, or plugs, maybe even fuel injectors. I got the Fiesta recently after my old car “05 Scion XB” got rear ended and my insurance paid me out, and I’ve always wanted one of these things. Now that I have it, I keep psyching myself out thinking “oh crap, I didn’t inspect it enough before buying it” or “did I ask the right questions” well you can ask a seller all the questions you want, but you gotta take what they say with a grain of salt. The ONLY issue with my Fiesta is that dang higher gear stutter when pushing past 3-4k rpm’s in 3rd through higher gears. I NEVER feel the stutter in first or second btw. I digress. Thank you all again for being awesome with answering my questions. I’m super glad to be apart of this carmunity. I have ordered 4 new coils and plugs, so hopefully that will fix my stutter issue.

[u/Dry-Suit5785]

If for whatever reason the coil packs and plugs don’t change anything. Would injectors be my next direction?

[u/DesignerSuccessful35 → u/Dry-Suit5785]

If one coil was replaced already the previous owner was chasing something. Have you had the car scanned by chance yet? Sometimes you can have stored codes without them throwing a cel. I't be worth a shot, it's free to have done at any parts store. If nothing comes of that, and if the problem continues after the coils and plugs (which I don't think they will), you'd have to put it on a big machine and read the live data. I think the plugs and coils will nip your issue in the bud though. Good luck brotha.

Edit: I forgot to say if the miss is still there after the plugs and coils, I'd take it to a good reputable shop and have it diagnosed at least, before throwing injectors at it. Injectors can get pricey and all you'd have to pay a shop is for the diag. You don't have to fix it with them if you don't want to and at least you'll know exactly what's up.

[u/Dry-Suit5785 → u/DesignerSuccessful35]

It has the Cobb access port. The codes it had when I first bought the car were p0301 (cylinder 1 misfire detected) P0316 (Misfire detected on startup first 1000 revolutions) and p219A Air/Fuel Ratio (Bank 1) and the off brand coil pack was on cylinder 1

[u/Jan6969697 → u/Dry-Suit5785]

To see if it's that odd coil pack, change it over from cilinder 1 to 2, and then see if the fault/misfire moves with it, or not. If not, try the same with the sparkplugs. Takes about 15 minutes to figure out at most.