2nd Gear Engine stops between 4-5k rpm

[Focus_Rider]

Hello y'all I'm new here and just got my 1st ST. and love this thing. It is a 2019 Fiesta ST and when I got it it had some surging related issue, at the time was "rectified" by the Ford dealership I bought it from. Well, I've owned this vehicle for about 2 months, and the surging comes after fueling up. WELL today I had something unique happened. Just the other day I went on a roughly 100mile trip no issues. Today I noticed when in 2nd gear and doing a WOT pull or just cruising in 2 and between 4k-5k RPMS the engine. I guess suddenly stops accelerating. It won't die and if I try to push it, it will act like there's no boost, wont do much of anything. No MIL on at this time The moment I shift into 3rd all is fine. No issues in any gear but 2nd. The ONLY thing I have done differently was when I came back home from my trip, I added 4 gallons of mid-grade (mixed it with the high-grade fuel in the tank) I just wanted to get some opinions. I got that ford extended warranty 3yr/36k but with this being my only vehicle atm I kinda want to figure it out before I commit to dropping it off for a week at the dealership.

 

[Zeille]

what do your fuel trims look like? especially low side fuel pressure? i had an issue where this would happen at the most random times in 3rd gear, and it was my low side fuel pressure sensor. car would bog down, not accelerate, and not build ANY boost, then come back on like nothing happened. do you have a COBB accessport?

 

[Focus_Rider]

Nop no cobb, So I found something interesting. I got my scan tool and found a P0001 for a circuit performance for the High Pressure fuel pump sensor (no check engine light). At I didn't think to look at the fuel trims because it was idling just fine. But my computer wasn't seeing data from the sensor and the car would just STOP . So I thought is was a boost related problem because it only happened on acceleration. I have a ford extended warranty so I too it to them and they verified it was a HP Fuel Pump.

 

[Focus_Rider]

Anyone who sees this have you guy had any issues when you rev the car and let it idle down and it drops well below normal idle point and the engine bogs. Only happens after the car sit up for a while but if you drive it for a few minutes we are good.

 

[Zeille]

Anyone who sees this have you guy had any issues when you rev the car and let it idle down and it drops well below normal idle point and the engine bogs. Only happens after the car sit up for a while but if you drive it for a few minutes we are good.

I've not had an issue like that with my fiesta, but I had that kind of issue on my 2007 Cobalt SS, which the solution was simply cleaning the throttle body. I would think of the purge valve with the way the issue sounds, as my car would stumble (only after fill-up, then subsequently at random times when driving when the low side fuel pressure sensor was giving me issues). I would like for other people to chime in on this - I'm absolutely not a professional at diagnosis or car work.

 

[Focus_Rider]

I've not had an issue like that with my fiesta, but I had that kind of issue on my 2007 Cobalt SS, which the solution was simply cleaning the throttle body. I would think of the purge valve with the way the issue sounds, as my car would stumble (only after fill-up, then subsequently at random times when driving when the low side fuel pressure sensor was giving me issues). I would like for other people to chime in on this - I'm absolutely not a professional at diagnosis or car work.

I've been working on cars (just got out of it) as a Main shop technician for Honda and GM and a few other dealerships for the last 8 years. BUT I've only worked at the dealerships and they do NOT train people to diagnose. They train you to see patterns in symptoms and follow trouble shoot procedures. With that being said Even with my uber expensive Snap-on scanner I am not 100% sure if the PID data i'm looking at is normal or not. If my scanner allows it I will try and command the Purge valve to make sure its opening smoothly. Other than that its very intermittent and I suppose it never hurts to clean the TB.
When I bought the car (from a ford dealership) It had an issue on the test drive where the idle was bobbing at idle. The technician told me the MAF was dancing around and he cleaned it with a cleaner and it actually did fix the fluctuation.

 

[Grsemky]

I've been working on cars (just got out of it) as a Main shop technician for Honda and GM and a few other dealerships for the last 8 years. BUT I've only worked at the dealerships and they do NOT train people to diagnose. They train you to see patterns in symptoms and follow trouble shoot procedures. With that being said Even with my uber expensive Snap-on scanner I am not 100% sure if the PID data i'm looking at is normal or not. If my scanner allows it I will try and command the Purge valve to make sure its opening smoothly. Other than that its very intermittent and I suppose it never hurts to clean the TB.
When I bought the car (from a ford dealership) It had an issue on the test drive where the idle was bobbing at idle. The technician told me the MAF was dancing around and he cleaned it with a cleaner and it actually did fix the fluctuation.

Our USDM cars are map based so cleaning the MAF wouldn't change anything and was more than likely coincidental