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Discussion Starter · #1 · (Edited)
My 2013 Focus ST2 with 91,xxx miles on the clock is acting up on me. This morning on my way to work it stalled 3 separate times as I was coming to a stop with the clutch pedal fully depressed. In the few weeks prior its happened once or twice randomly, but never before that and I've owned it from brand new. My car has always had weird idle quirks though. I redid all the splices in the harness and addressed the grounding issues myself. I've always kept up on my spark plugs (new set installed recently and gapped correctly). My gut tells me my problem lies somewhere in my fuel system based on all the threads I have read. Whatever it turns out to be I need to address it quickly because I'd hate to find myself in a wreck due to my car stalling unexpectedly.

*I should also mention that I have no codes present or nor did any set when the stalls occurred.

**I will try my best to get a data log the next time it happens to see if that provides any useful direction.
 

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dirty/clogged injectors perhaps? Have you done a valve cleaning yet?
 

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Discussion Starter · #3 ·
dirty/clogged injectors perhaps? Have you done a valve cleaning yet?
Perhaps as I have not looked at those or done any kind of valve cleaning yet.
 

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Discussion Starter · #5 ·
If its fuel related, you should be able to log it. Sounds like something else though. Could be a clogged 02 sensor?
I'm open to all reasonable suggestions as to where/what the culprit might be.
 

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Clogged O2 would throw thresh hold codes though wouldnt it?

If its fuel related, you should be able to log it. Sounds like something else though. Could be a clogged 02 sensor?
 

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Buddy of mine just checked fuse (i think it was 56 in the passanger footwell) that controls the fuel pump/ mass flow) and it was shorting, replaced it with a new fuse and everything was fine. He was having it shut off every time during a stop. Just something you may want to look into.
 
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Discussion Starter · #8 ·
Buddy of mine just checked fuse (i think it was 56 in the passanger footwell) that controls the fuel pump/ mass flow) and it was shorting, replaced it with a new fuse and everything was fine. He was having it shut off every time during a stop. Just something you may want to look into.
I'll definitely take a look at that since its a quick and easy one. Thanks!
 

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I would try to get a camera in and look at the valves. Dirty valves with DI can cause horrible idling issues. Could have an issue with the pcv system. You've got 3 sources for idle issues: air flow (valves, leaks, pcv system...etc), fuel (everything from the intank pump, to the di pump, fuel lines and injectors), and lastly the electrical aspect (anything from the tune, spark, gremlins of sorts).

Don't rule out the tune without looking at logs. The tune could be compensating for something else that is a problem.
 

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Discussion Starter · #10 ·
I would try to get a camera in and look at the valves. Dirty valves with DI can cause horrible idling issues. Could have an issue with the pcv system. You've got 3 sources for idle issues: air flow (valves, leaks, pcv system...etc), fuel (everything from the intank pump, to the di pump, fuel lines and injectors), and lastly the electrical aspect (anything from the tune, spark, gremlins of sorts).

Don't rule out the tune without looking at logs. The tune could be compensating for something else that is a problem.
Yeah I'm not ruling anything out at this point since I don't have much to go on. Since it is my daily I probably won't be able to tear into it too much until I'm off this Friday.
 
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Discussion Starter · #12 ·
probably. Never know with the focus. Sounds more electrical though to be honest.

How does the car run outside of this one specific issue?
It runs strong while driving, but like I said it has always been a little quirky at idle. I've experienced the idle dipping when coming to a stop, but it would always catch itself, shoot up past idle and then settle. This always seemed more pronounced when the A/C was running due to the additional load of the compressor. What makes me feel its fuel system related is it seems to act up more when I have a full tank of gas which I did this morning. Also worth noting is today was one of the coolest we've had here in DFW since a cold front rolled through last night (~55 degrees out as opposed to ~80). I troubleshoot military aircraft problems for a living (work for Lockheed Martin on the F-35 Program) so I'm confident I can chase this down and welcome/appreciate any advice y'all throw my way.
 

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It runs strong while driving, but like I said it has always been a little quirky at idle. I've experienced the idle dipping when coming to a stop, but it would always catch itself, shoot up past idle and then settle. This always seemed more pronounced when the A/C was running due to the additional load of the compressor. What makes me feel its fuel system related is it seems to act up more when I have a full tank of gas which I did this morning. Also worth noting is today was one of the coolest we've had here in DFW since a cold front rolled through last night (~55 degrees out as opposed to ~80). I troubleshoot military aircraft problems for a living (work for Lockheed Martin on the F-35 Program) so I'm confident I can chase this down and welcome/appreciate any advice y'all throw my way.

It happens more often when the tank is full? Sounds like a bad purge valve.
 

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Discussion Starter · #14 ·
It happens more often when the tank is full? Sounds like a bad purge valve.
That is what I'm leaning towards biased on my symptoms and from what I've read on here.
 

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Discussion Starter · #18 ·
im at 155k. I barely drive my ST anymore. I think i've put on like 2k miles since January, but i've owned the car for 5 years.
Well definitely a worthwhile avenue to explore. Thanks for your input!
 

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Had this early on (~50k mi) with my '14, had it towed to my dealer. They claimed there was some junk built up in the MAF (lol, there's no actual MAF, but the MAP sensor right near the intake), they cleaned it out and it cleared up. They blamed my green filter and didn't warranty it.

I figure it's worth looking at cleaning that MAP just in case.
 

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Discussion Starter · #20 ·
Had this early on (~50k mi) with my '14, had it towed to my dealer. They claimed there was some junk built up in the MAF (lol, there's no actual MAF, but the MAP sensor right near the intake), they cleaned it out and it cleared up. They blamed my green filter and didn't warranty it.

I figure it's worth looking at cleaning that MAP just in case.
I'm putting together a short list of things to look at since there may not be a smoking gun, but a combination of things contributing to my problem. Plus nearing that 100k mark I wanna do my part maintenance wise. There was a good write-up I saw the other day about walnut blasting which I'm sure my valves could benefit from too.
 
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