Bro keeps dying while slowing down

[GabzRK]

Hi, yes, I did make an account just to post this, but I've been reading various old posts regarding my baby's "issues."

So, a little background:
It's a 2016 Ford Fiesta ST w/ some sort of aftermarket intake (I didn't buy it; I can look if you absolutely wanna know) and a Stage 1 Tune run on 93. It has about 64,000 miles and I got a new battery probably 1k miles ago.

I bought it late September of 2023 from a used suburban ford dealership, and yes the engine light came on like that first week I had it, and no it's not warranted. L

I have a Cobb access port that came with the car, and I know that it has code P1450 (unable to bleed up fuel tank vacuum) 24/7 and occasionally has P0420 (Catalyst system efficiency below threshold (bank 1)) and P0456 (Evaporative emission system leak detected (very small leak)) but they haven't popped up in a couple of months.

Now: It typically drives as expected (sometimes it does the usual stalling after refueling thing); however, within the past 2 months, it began not turning over after refueling. It clicks but doesn't turn over, so I have to give it a couple of minutes and make sure I am also lightly pressing the gas when starting, and it works fine after that. I tend to run it until I have less than 20 miles pretty frequently and I was told that was likely the cause due to burning vapors.

Last Monday, I stopped at Tim Hortons on my way to work cause I had low blood sugar, and I noticed my car got really quiet. I looked at my dash, and it did the usual flash of Christmas lights when it stalls, and I thought it was on me. Except it kept doing it. I even got sick and didn't drive it after that for a week, but it did it today, too. When I'm slowing down or idling, it just dies, even if I'm moving. I am not even stalling because a message always pops up saying, "Press the clutch to start" when I stall. It just gets really quiet, and it only happens when I'm in neutral, so it doesn't "jump" like it does when stalling "manually." Also, my dad bought me some fuel injector and whatever cleaner and I put it in there this morning - no change. </3

Does anyone have any tips?

 

[XanRules]

Figure out what kind of intake you have and post a photo - there are known issues with some intakes, especially on 2016+ cars, causing issues with the evaporation system that contributes to stuttering and hesitation, and sometimes outright stalling, after filling up.

Also post whatever other modifications you have - who did your tune, how is it tuned, etc.

 

[GabzRK]

View attachment IMG_9657.jpeg View attachment IMG_9658.jpeg
Here are some that I just took. As far as the tune, there was a set of stage 1, 2, and 3 with 87, 89, 93 available on the cobb. When I got it, it was set to 3 on 93. A quick google suggested that wasnt good for longevity if I only had an upgraded intake, so my bf suggested changing it to stage 1 on 93. Idk anything about tunes or the previous owner’s plans, so I’m unsure if that was preprogrammed or done somewhere and imported.

I did notice while driving home, it does rough idle when the gas is not actively being pressed and it’ll tend to do that until it ultimately stops or idles normally. 50% of stops or neutral periods are normal and 50% it dies.

 

[TyphoonFiST]

What you need to do is get a scan tool that can run and Emissions test that will clear or fail the system. Id be curious to see how they have the Emissions harness with the Purge valve setup underneath the intake you have in this picture. Another thing you could do is clean the Capless fuel system also.

View: https://youtu.be/JlK2qekqX5s?si=jwGVHZ5-i5PJmdJD

 

[akiraproject24]

Based on the available info you've provided, if it were me (and I'm retarded) I'd do this

I'd replace the purge valve assembly (octopus looking thing connects to cold side pipe and intake etc). I'd probably also do the vent canister solenoid (small solenoid that lives down by the fuel tank/charcoal cannister) and I'd want to look at the downpipe to see if it is catted or catless or aftermarket in general.

Secondarily I'd probably replace that intake with oem or ST200 if and when I could find someone parting with it for a good deal.

I'm no trained mechanic however, I just enjoy wrenching on my cars

Could also check for torn or disconnected vacuum hoses or their connectors not fully seated

 

[XanRules]

View attachment 64321 View attachment 64322 When I got it, it was set to 3 on 93. A quick google suggested that wasnt good for longevity if I only had an upgraded intake, so my bf suggested changing it to stage 1 on 93.

This is likely your problem. It sounds like you don't know that all you have is an upgraded intake - "Stage 3" is for an upgraded intake, intercooler, and catless turboback exhaust. Running a stage 1 tune with all of these mods can cause the issues you are describing.

 

[LucasHigh]

Based on the available info you've provided, if it were me (and I'm retarded) I'd do this

I'd replace the purge valve assembly (octopus looking thing connects to cold side pipe and intake etc). I'd probably also do the vent canister solenoid (small solenoid that lives down by the fuel tank/charcoal cannister) and I'd want to look at the downpipe to see if it is catted or catless or aftermarket in general.

Secondarily I'd probably replace that intake with oem or ST200 if and when I could find someone parting with it for a good deal.

I'm no trained mechanic however, I just enjoy wrenching on my cars

Could also check for torn or disconnected vacuum hoses or their connectors not fully seated

and also its common the o rings on the evap harness connection tear especially while removing I would check for that first as its the cheapest option

 

[GabzRK]

This is likely your problem. It sounds like you don't know that all you have is an upgraded intake - "Stage 3" is for an upgraded intake, intercooler, and catless turboback exhaust. Running a stage 1 tune with all of these mods can cause the issues you are describing.

Hmm good point, it didnt look like those mods were done, hence it was changed to stage 1, but I’ll look into it

 

[GabzRK]

Okay so an update…

1. I have had a hard time finding the ability to do an emissions test, they aren’t mandatory in Michigan and so no one really offers it, but my capless does look pretty clean.

2. I used my cobb to monitor some things while driving, and I noticed my cat runs hot for what it’s supposed to, but not extreme - I presume it may be dying. It gets up to about 1200 F during normal driving and never goes below 800.

3. I dont have any modifications beyond the upgraded intake (from what I can tell). Particularly the intercooler and exhaust, they are oem despite being run on a stage 3 tune before I bought it.

4. i bought a bottle of this yesterday, as it’s suggested before replacing your o2 sensors, but I havent used it yet.
https://www.autozone.com/fuel-and-e...28488_0_0?searchText=Fuel+and+exhaust+cleaner

Ive gotten away with driving it without stalling as long as i stay under 3k rpm and drive reasonably (no pulls unfortunately). Also if anyone knows some other things I can measure with my accessport lmk. I’ve been doing a lot of research before doing anything, as engine codes can mean a plethora of different things, and I want to make sure I do things right.