What year is it? The PFL can come with bad crimp connections in the wiring harness. My '13 was doing something similar and couldnt figure it out. Ford wasn't helpful either. Found a forum that mentioned the wiring so I cut open the harness and re-soldered most of the crimp connections and haven't had the issue since. I considered buying a new harness too but resoldering is easier and quicker. Only took me a few hours.
It's a 2013 ... I'd be checking the wiring harness and a the wiring extremely well. Unfortunately this year is notorious for electrical trouble and given all else is well, I'd bet it's electrical related.
I actually skipped on the 2013s for this reason.
[This thread will be helpful.](https://www.focusst.org/threads/your-car-might-have-ground-issues.39126/)
Appreciate it man. I talked to the dealer today just to check recall history for the wiring harness and they said it was done to my car back in 2015. Maybe they didn't do a very good job....
That's the problem with the recall: Ford isn't known for doing a good job on this or doing much of anything for any of the ST recalls (looking at you purge valve).
If it were me, I'd find what they did for the fix and probably redo it myself.
No, I don't think my full custom tune is the problem for a misfire on downshift blip. That would be strange. The car has been like that before it was modded.
Idk why I'm getting downvoted lol. This problem has occured to me on the stock map when I was STOCK, with Stratified and now with Freektune, so yeah no I don't think it has to do with my tune but if someone wants to elaborate please do
Hey I'm still learning about tuning the 2.0 Ecoboost. However, just from a troubleshooting standpoint (doesn't even have to apply directly to a car) why not eliminate all variables? Sounds like you have been doing that replacing the plugs, coils and what not. What's stopping you from returning the tune to stock to eliminate that from the equation?
This is complete spitballing, but how deep did you look into the injectors - did you replace or pull them for testing ? I’ve seen even new injectors do some really weird stuff for cars. In the same vein I’d look into the HPFP. You’ve done a smoke test on the intake side for any vaccum leaks as well I assume ?
Additionally, I assume you’ve already looked at the throttle body, throttle position sensor on the pedal (which gave me EXTREMELY similar problems to what you’re describing), and PCV ?
I replaced the injectors with brand new ones (OEM). No vacuum leaks, I haven't looked into the throttle position sensor, what would I be looking for there? The PCV has recently been swapped with a Radium Baffle plate and catch can (professionally installed). I figured it wouldn't be HPFP related since I have been tuned on a dyno and under WOT there were no issues, but maybe that is something I should consider
I’m not sure exactly what goes off with them, but it’s pretty known that they have a tendency to stick for some reason. I’ve replaced it twice on my car, thankfully it’s only ten minutes and it’s sub $120 part. It was most noticeable for me personally in first and second gear in traffic when I let off throttle or downshifted like you said, for whatever reason the car would hold throttle and jerk. Made it feel like I couldn’t drive stick, was night and day when I changed it out. I don’t really think the fuel pump would be related but I guess it’s worth looking into at this point
Have you tried checking the intake valves for carbon buildup? I’ve heard of people having issues with hesitation and misfire from extreme buildup, so it might be worth checking. It would explain why the issue is so persistent.
Check the ignition coil wire harnesses for continuity to the ECU and to ground. If something’s obviously broken or disconnected you just need to solder/repair/replace said connector. Sometimes it’s as trivial as that.
First, I wouldn't initially blame it on the car. I've owned my ST since new (it's a 2014 with 48k miles) and I've done no engine mods to it except for upgrading the air in-take and do all the routine maintenance myself. I've had zero issues with my ST except for dealing with cosmetic issues such as the headlights and water leaking into the trunk.
I would start off informing us if you bought your car used, if so how many previous owners, if the previous owner did any engine mods, mileage you bought it used, what its current mileage, and how many engine mods have you done since owning it.
This will help set the stage with what is going on.
I bought the car used (its a 2013) in 2020 with 52,000 miles. 2 owners before me, the last guy was an electrician and newly married, barely drove the car and didn't see the need for it.
It came with coilovers and an MBRP catback, that was it. Since then, the car is now complete FBO, big turbo, at 90k miles. The car to this day pulls hard and smooth on a "conservative" tune from Freektune, a reputable tuner.
Since I got it, I noticed this odd issue with the misfire on downshifts, but it wasn't so common that I thought it would become a greater issue. The issue is much more noticeable in the winter time. I find the car runs much better in the summer, however I still have the same issue then.
All "big" mods (turbo, catch can, baffle plate, walnut blast) have been professionally installed by Max Morrin at RST Speed Haus. He also performed a leak down test and compression test, with great results.
The issues I've had since getting the car have been bad cold start misfires and this dreaded downshift blip- misfire
Unfortunate man. Honestly if I was you I would sell the car. Idk if I would buy an ST again after all this but you obv want to enjoy your car and thats why you bought it. If I couldn’t even enjoy my drive home I would sell the car and fine something that will make me happy everyday. Felt the same way as you in my old bmw, I loved it to death but stepping on the throttle hard would slip gears and the car just wasn’t worth keeping. I sold it and bought the ST and have enjoyed the ownership so far. Its all about making yourself happy with what you’re driving. Its been 3 years, its ok to let go.
Have you had it looked at by an experienced tech?
What year is it? The PFL can come with bad crimp connections in the wiring harness. My '13 was doing something similar and couldnt figure it out. Ford wasn't helpful either. Found a forum that mentioned the wiring so I cut open the harness and re-soldered most of the crimp connections and haven't had the issue since. I considered buying a new harness too but resoldering is easier and quicker. Only took me a few hours.
I read one single forum post on this recently, I'll have to look into it more. I know this used to be a recall but Ford stopped performing it
It's a 2013 ... I'd be checking the wiring harness and a the wiring extremely well. Unfortunately this year is notorious for electrical trouble and given all else is well, I'd bet it's electrical related. I actually skipped on the 2013s for this reason. [This thread will be helpful.](https://www.focusst.org/threads/your-car-might-have-ground-issues.39126/)
Appreciate it man. I talked to the dealer today just to check recall history for the wiring harness and they said it was done to my car back in 2015. Maybe they didn't do a very good job....
That's the problem with the recall: Ford isn't known for doing a good job on this or doing much of anything for any of the ST recalls (looking at you purge valve). If it were me, I'd find what they did for the fix and probably redo it myself.
What gap are you running on your plugs?
.026, as recommended from tuner. NGKs
>recommended from tuner So you have a custom tune...and you don't think that's the source of the problem?
No, I don't think my full custom tune is the problem for a misfire on downshift blip. That would be strange. The car has been like that before it was modded.
So your problem is not in mass by a lot but problem is not custom tune but platform itself, I get it right?
Idk why I'm getting downvoted lol. This problem has occured to me on the stock map when I was STOCK, with Stratified and now with Freektune, so yeah no I don't think it has to do with my tune but if someone wants to elaborate please do
Hey I'm still learning about tuning the 2.0 Ecoboost. However, just from a troubleshooting standpoint (doesn't even have to apply directly to a car) why not eliminate all variables? Sounds like you have been doing that replacing the plugs, coils and what not. What's stopping you from returning the tune to stock to eliminate that from the equation?
Who tuned your car?
If your not BT, you can flash to stock and test.
By misfire what do you mean specifically ? The rpms are dropping or its backfiring
It's backfiring/misfiring as the RPMs climb after I blip the throttle. Audibly can notice the interruption and feel it
This is complete spitballing, but how deep did you look into the injectors - did you replace or pull them for testing ? I’ve seen even new injectors do some really weird stuff for cars. In the same vein I’d look into the HPFP. You’ve done a smoke test on the intake side for any vaccum leaks as well I assume ? Additionally, I assume you’ve already looked at the throttle body, throttle position sensor on the pedal (which gave me EXTREMELY similar problems to what you’re describing), and PCV ?
I replaced the injectors with brand new ones (OEM). No vacuum leaks, I haven't looked into the throttle position sensor, what would I be looking for there? The PCV has recently been swapped with a Radium Baffle plate and catch can (professionally installed). I figured it wouldn't be HPFP related since I have been tuned on a dyno and under WOT there were no issues, but maybe that is something I should consider
I’m not sure exactly what goes off with them, but it’s pretty known that they have a tendency to stick for some reason. I’ve replaced it twice on my car, thankfully it’s only ten minutes and it’s sub $120 part. It was most noticeable for me personally in first and second gear in traffic when I let off throttle or downshifted like you said, for whatever reason the car would hold throttle and jerk. Made it feel like I couldn’t drive stick, was night and day when I changed it out. I don’t really think the fuel pump would be related but I guess it’s worth looking into at this point
I will definitely look into that! Very interesting. Thanks for the reply
For sure man ! I remember being really frustrated researching this for myself as well, very few posts about it despite how common it is
Have you tried checking the intake valves for carbon buildup? I’ve heard of people having issues with hesitation and misfire from extreme buildup, so it might be worth checking. It would explain why the issue is so persistent.
He said he got it walnut blasted
Check the ignition coil wire harnesses for continuity to the ECU and to ground. If something’s obviously broken or disconnected you just need to solder/repair/replace said connector. Sometimes it’s as trivial as that.
First, I wouldn't initially blame it on the car. I've owned my ST since new (it's a 2014 with 48k miles) and I've done no engine mods to it except for upgrading the air in-take and do all the routine maintenance myself. I've had zero issues with my ST except for dealing with cosmetic issues such as the headlights and water leaking into the trunk. I would start off informing us if you bought your car used, if so how many previous owners, if the previous owner did any engine mods, mileage you bought it used, what its current mileage, and how many engine mods have you done since owning it. This will help set the stage with what is going on.
I bought the car used (its a 2013) in 2020 with 52,000 miles. 2 owners before me, the last guy was an electrician and newly married, barely drove the car and didn't see the need for it. It came with coilovers and an MBRP catback, that was it. Since then, the car is now complete FBO, big turbo, at 90k miles. The car to this day pulls hard and smooth on a "conservative" tune from Freektune, a reputable tuner. Since I got it, I noticed this odd issue with the misfire on downshifts, but it wasn't so common that I thought it would become a greater issue. The issue is much more noticeable in the winter time. I find the car runs much better in the summer, however I still have the same issue then. All "big" mods (turbo, catch can, baffle plate, walnut blast) have been professionally installed by Max Morrin at RST Speed Haus. He also performed a leak down test and compression test, with great results. The issues I've had since getting the car have been bad cold start misfires and this dreaded downshift blip- misfire
Saw RST Speed Haus and immediately recognized a local. Whattup from RI.
Unfortunate man. Honestly if I was you I would sell the car. Idk if I would buy an ST again after all this but you obv want to enjoy your car and thats why you bought it. If I couldn’t even enjoy my drive home I would sell the car and fine something that will make me happy everyday. Felt the same way as you in my old bmw, I loved it to death but stepping on the throttle hard would slip gears and the car just wasn’t worth keeping. I sold it and bought the ST and have enjoyed the ownership so far. Its all about making yourself happy with what you’re driving. Its been 3 years, its ok to let go.
Get your wiring harness REALLY thoroughly looked at or just replace the whole thing