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I had the purge valve recall done, was hopeful but it didn't correct my misfire issue. So they started testing everything and ended up pulling the cylinder head to find a head gasket leak on cylinder 3, same cylinder most of the misfire codes were popping up on. They'll hopefully have it back together this week and I'll see if we have finally gotten to the bottom of the this intermittent misfire issue I have been having.
 

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2018 ST just threw a code on a cold start an hour and a half ago. Say a prayer for me guys... Gonna go get it checked out in a few minutes...

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Yep I've had both of those, I've had my car back about 2 weeks now since they replaced the head gasket, so far so good. However I have gone months at a time before with no CEL being tripped, so if I make it to next winter with no misfire codes I'll consider it fixed. I currently have their latest tsb for misfires applied and my purge valve was replaced as part of that recall.


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Yep I've had both of those, I've had my car back about 2 weeks now since they replaced the head gasket, so far so good. However I have gone months at a time before with no CEL being tripped, so if I make it to next winter with no misfire codes I'll consider it fixed. I currently have their latest tsb for misfires applied and my purge valve was replaced as part of that recall.


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What does the latest tsb for the misfires consist of?
 

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What does the latest tsb for the misfires consist of?
As far as I know just some newer software changes, they still install plugs gapped at .040".


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So, I just had this same issue replaced the spark plugs, but still getting a **** ton of misfires, but no engine light or codes popping up. its 17 ST with 15k miles...rip
 

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Ok I wanna give a heads up to the worry warts in here. I bought my 2018 with 60 miles on it back in March if last year. At around 5k I got a cold start misfire code, took it in they did that worthless TSB with new plugs which from what I have heard are fiesta plugs if I remember correctly which are "supposed" to be gapped down to .040, which questioned them about because that's entirely to big and asked about the software mod, well come to find they change the timing event somewhat because they say the combustion was bending spark plugs. Well I got home, never through a another check engine light but after about 200 miles, I popped the plugs out and checked them they gapped them to the normal .028, not the .040 the tsb called for. So anyways I popped those **** plugs out put in some 6510s and loaded my accessport and I haven't had any hard misfires yet. So now, does the car still have misfires yes of course, I have owned this car long enuff now and a Speed6 also, and these ecoboost motors are just notorious for low end cold start warm up open loop mis fires. I can literally tell in an instant when my car goes from open to closed loop at full operating temp because any lil misfire I may have been getting disappears. I have had my compression checked at 22k and I was 170 across all 4 and I'm at 32k now running great. I still have lil bumples and mumbles but only during warm up and an occasional one here and there but nothing that throws check engine lights at all and I check my accessport for hard and soft codes every week or two just to be safe. Just a heads up for people thinking that a misfire means **** death oh now, don't sweat it so much.
 

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So took my car to the dealership service center...cleared the codes, check the spark plugs did the TSB and still have misfires, but no codes...any suggestions? 15k miles
 

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Ok I wanna give a heads up to the worry warts in here. I bought my 2018 with 60 miles on it back in March if last year. At around 5k I got a cold start misfire code, took it in they did that worthless TSB with new plugs which from what I have heard are fiesta plugs if I remember correctly which are "supposed" to be gapped down to .040, which questioned them about because that's entirely to big and asked about the software mod, well come to find they change the timing event somewhat because they say the combustion was bending spark plugs. Well I got home, never through a another check engine light but after about 200 miles, I popped the plugs out and checked them they gapped them to the normal .028, not the .040 the tsb called for. So anyways I popped those **** plugs out put in some 6510s and loaded my accessport and I haven't had any hard misfires yet. So now, does the car still have misfires yes of course, I have owned this car long enuff now and a Speed6 also, and these ecoboost motors are just notorious for low end cold start warm up open loop mis fires. I can literally tell in an instant when my car goes from open to closed loop at full operating temp because any lil misfire I may have been getting disappears. I have had my compression checked at 22k and I was 170 across all 4 and I'm at 32k now running great. I still have lil bumples and mumbles but only during warm up and an occasional one here and there but nothing that throws check engine lights at all and I check my accessport for hard and soft codes every week or two just to be safe. Just a heads up for people thinking that a misfire means **** death oh now, don't sweat it so much.
how rough does your FoSt idle?
 

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I noticed if I turn on AC at first start in the morning car idles fine with no misfires.

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Yea mines the same way sometimes. What it seems to be is the area between like 1500 to 1750 rpms it really likes to miss until its warmed up, as soon as it drops out of Open loop the misfires disappear like our ozone layer. I am not sure what or why it does this, but it has something to do with coolant temp, and the open loop fueling during warm up. Because the moment my car hits what the ecu considers full operating temp and drops from open loop its literally like a light switch. You can also feel it while you drive, if you go and start driving a minute or two after starting your car which I know many do, I don't, its opinion, but anyways if you start driving and dont beat on it but just cruise you can also feel when it goes from open loop to closed because the kinda miss in the throttle pedal disappears. I know for me if I drive before its completely warmed up itll feel kinda sluggish at lower rpms, unless you keep in like 1st or 2nd and just ride gear at like 2500 or 3k rpm, but the temp gets right and boom its really weird. Anyways, this may have to do with cylinder temps getting up to temp and until they do the bowl of the piston doesnt create a good atomization of fuel, I know that in the RS motors the 2.3 piston bowls on top were revised to help with a better fuel burn and that may have something to do with the fact that the RSs and mustangs never had the misfire issue.
 

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So, my 2017 ST (63500km / 37k miles-ish) has been struggling with this this summer. Started with the surging and a CEL plus idling really rough and just not driving right around the start of July. Dealer replaced 2 plugs and an ignition coil. I had the purge valve recall done when it came out however long ago. At least I think I did. Asked dealer to check in.

Anyway, since the first fix, no more CEL but rough idle and surging did persist, albeit less then before. Took back to dealer, more misfires and replaced a plug. Now last week it stalled on me at a light and wouldnt stay running unless I held the gas. Went into the dealer, left it there as i'm going for a week to Europe. Went in and advised them there are some TSBs and this has happened to other people's ST's. As of yet they haven't started working on it.

What am I in for in terms of getting this actually, permanently fixed so I can enjoy my car as it was?
 

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Have them actually check/replace the purge valve. The recall didn't automatically replace the part... It was a software update and then they would replace the valve + gas tank if needed.
 

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376630
Engine blew at 59k covered by warranty. 2k into a new engine and this is the 4th time getting misfires. This time around I had misfires in every cylinder but number 3. Last few times cylinder 3 was included. Cold start idles causing them. Also car will bog down when I come to a red light or stop sign. Not amused. No tune. Rs air box/cat back.
 

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View attachment 376630 Engine blew at 59k covered by warranty. 2k into a new engine and this is the 4th time getting misfires. This time around I had misfires in every cylinder but number 3. Last few times cylinder 3 was included. Cold start idles causing them. Also car will bog down when I come to a red light or stop sign. Not amused. No tune. Rs air box/cat back.
My engine blew at 59k too.. spun a bearing on the connecting rod on cylinder 4. I just got mine back like a week ago. Almost 1k on it now. Haven't had any misfires though. I definitely had that problem with the old motor. If the temp was below 40, it was hit or miss but it threw the CEL quite a few times.

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My engine blew at 59k too.. spun a bearing on the connecting rod on cylinder 4. I just got mine back like a week ago. Almost 1k on it now. Haven't had any misfires though. I definitely had that problem with the old motor. If the temp was below 40, it was hit or miss but it threw the CEL quite a few times.

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Dude that’s crazy. I was 59,363 miles. I did have a stratified tune on it tho. Got lucky I knew the dealership, they knew I had it tuned. From what I read in this thread it just happens? I don’t notice any driving issues. Just the rough idle n misfires/bog down at red light stops. Both engines did it. This new one is non stop cels tho. I garage keep at 60 degrees n back it out into cold newyork mornings. I did notice that it happens when I start the car and don’t gas it at all n let it warm up without reversing out the garage right away. Idk its going to ford tmr.
 
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