2015 Fiesta ST Warm Start issues (Resolved as of 2/11/24)

[Tungsten]

Hey y’all,

I’ve been having issues with my car recently stalling after a warm start. I found another post on this forum describing pretty much exactly what I’m experiencing.

Here is a link: https://www.fiestastforum.com/threads/rough-idle-stalling-issue.28573/

Quote from the link:
“I have a 2016 FiST that I've had for a little over a year now and around the year mark it started doing this thing where if I started it cold and drove it would be fine, but if I stopped and shut the car off to go into the store or whatever and then went to start it, by the time I shifted into second and get to around 2k-2.5k RPMs it would just lose all power and when I came to a stop it would idle at around 500rpm until I shut it off and started it again. It got progressively worse…”

No codes have been displayed for this. My Cobb AP doesn’t show any DTC codes despite a check engine light coming on sometimes. Any information and help would be incredibly helpful. I will attempt to attach/link some videos of the issue.

Thank you.

Links:
https://youtube.com/shorts/diFvDvuPgzk?si=WVpBELqOkv2gRiBi

https://youtube.com/shorts/R5lRu9mMzoM?si=zKqFbexSj2KUwNfT

 

[Tungsten]

The issue is yet to have happened to me at high speeds. Only ever while at idle, 1st gear, and sometimes 2nd gear.

 

[Tungsten]

I have found the following forum thread that describes a similar issues to mine.

Link: https://www.fiestastforum.com/threads/fuel-pressure-issues-help.30000/

TyphoonFiST identified the Low Pressure Fuel Sensor as being the issue. I’ve ordered the replacement part and will get it installed ASAP to hopefully fix my issue.

 

[Intuit]

I know you said their are no codes despite the check engine light, but that makes absolutely no sense. What alterations have been made?

 

[Tungsten]

I know you said their are no codes despite the check engine light, but that makes absolutely no sense. What alterations have been made?

I’ve tried multiple times to use my Cobb AP to scan for any DTC codes when my car stalls. Each time the Cobb AP says there aren’t any. It’s pretty strange. What do you mean alterations?

 

[Intuit]

It's probably not reading from all the modules. Try to read the check engine light code from https://forscan.org/ .

 

[Tungsten]

It's probably not reading from all the modules. Try to read the check engine light code from https://forscan.org/ .

I’ll give that a try. Hopefully it’ll get me somewhere.

I’m able to monitor the Fuel Rail Pressure with my Cobb AP. I tracked the pressure while in idle and it’s usually at ~600 psig. The pressure then nosedives to ~50 psig, then the engine starts to stutter and after a few seconds stalls. Useful information. I’m hoping the issue is the Low Pressure Fuel Sensor.

 

[Tungsten]

It's probably not reading from all the modules. Try to read the check engine light code from https://forscan.org/ .

The engine light came up again tonight. I used the Cobb AP to read current DTC codes and it actually worked this time.

It’s a P0087 code “Fuel Rail/Pressure - Too Low”

Sooooo pretty much what I had said earlier today. The new Low Pressure Fuel Sensor came in today. I’ll install it tonight or tomorrow and see if the issue persists. I’m hoping it’s not the Low Pressure Fuel Pump giving out.

 

[Intuit]

Vaguely recall a recent thread on this. Dunno if it was the exact same code but it was intermittent low pressure.

 

[Tungsten]

Vaguely recall a recent thread on this. Dunno if it was the exact same code but it was intermittent low pressure.

I replaced the Low Pressure Fuel Sensor a little over a week ago.

I am happy to say the problem has not reappeared since then. I think it’s safe to say the sensor was the issue.

Thank you for your help!

 

[Intuit]

Interesting. Assuming resolved, replacing the sensor implies that there wasn't actually a low pressure condition. By dropping power at the "sight" of low pressure, it seems Ford is attempting to protect the engine from possibly damaging lean condition. Nice feature.