I'd have it cleared and then drive to see if it's fine.

It could've been the fuel door.

 

The fuel door won't cause a code, or a misfire. The little flapper that is part of the capped system will, but it would be evap, not misfires.

Could have been some funky gas... Base engine, ignition problems... Hard to say. If you don't feel it, or the engine lamp isnt flashing, it "probably" isn't going to cause caytalist damage... But I wouldn't clear anything. Because you will remove and info the dealer will need. Get it to them as soon as they will allow it.

 

Thanks.

Agree about the fuel door.

I took the car out last night in the cool evening weather without the ac on and went for a quiet drive. It drives just fine. I kept it under 4k rpms and it runs the way it always has.

The good news is that I found a local dealer that can see me this afternoon.

I'll update this thread once I find out more.

 

When I tell you this I'm not being a **** at all. A misfire code that stays on in this car usually means one thing its new motor time. Drive it till it dies to insure you get a complete new motor under warranty

 

How do you figure that logic? There have been tons of people with cold start misfire issues with less than 5k miles on their cars that have had whole heads, ignition and almost whole fuel systems replaced and still have misfires. For me as an example I bought a 2018 St2, that had all but 0 miles on it broke it in religiously, less then 5k, one day i started it and had a misfire code only on cold start up, literally you can tell as soon as it leaves open loop during warm up the misfire leaves instantly. So anyways, took it to Ford ASAP they put there TSB in for it, which is some retarded gapped plugs and some new calibration to change the timing of combustion events, worked well, surprisely enough the new gap didn't effect the power or give any blow out during top end boost, which was my worry. I will say it still has some what of a misfire or something during warm up, but the minute the temp gauge hits full operating temp it literally is like it shuts off a switch. Which the only thing I can figure is that its going from open loop to closed loop fueling. And also, if the motor someone is referring to has proper compression, and isn't burning any oil, I don't see how you could automatically say it needs a new motor, given they replaced peoples motors before and still had the issues. Unless your talking about a different kind of misfire that is cylinder selective, where a certain cylinder is always the same one misfire, that would lead me to beleive that particular cylinder may have issues, but as far as a random cylinder misfire during cold start I dont think necessarily means new motor.

 

Have you cleared the code to see if it returned? Do that first. The fuel filler door will not cause a misfire code.

 

No, I haven't cleared the code. Once i had it read, I set out to get it looked at by a dealer as soon as possible.

 

I'm having the same codes appear on and off, so far nothing the dealer has replaced did help me.

 

ive hand the same issue before i cleared it and it went away. My issue was if you ever notice there is a hesitation between 1500 to 1900 rpm which even with the latest ecu update is still there. That is causing random misfire.

 

Also I'd recommend to check that your grill shutters are all open when the car is off.

The motor actuates only one shutter blade; the rest move via a center vertical connection bar that easily breaks/comes undone, leaving only 1/4 of the shutters open, or just the one blade.

The shutters open fully when the car is turned off. When the ignition is turned on, the shutters go through a self-calibration motion and close -- until the car warms up sufficiently to cause the ECU to (attempt to) open them in varying degrees.

So, if the shutters are closed when the car is parked and turned off, the car will get quite warm as the shutters will never open, and in combination with marginal gas, that can sometimes cause a misfire.

Hope that helps,
Mark

 

Well, after about 90 minutes at Fair Oaks Ford in Naperville (super nice new showroom/waiting area), I've got the car back.

They ran a cylinder power balance test which the car passed. They also checked the ignition coil connections and those were all good too. They reset the code, ran it for a little bit and it didn't come back up. Basically, it's all good.

Drove it home, pushed it past 4krpm for the first time since the light came on and I didn't throw a code or explode so that's good.

Fair Oaks Ford in Naperville IL... good dealer.

 

One last question on this subject of a misfire...

Prior to getting that CEL on Tuesday morning, I drove the car on Monday night with very low fuel. When I eventually refuelled, the car was saying I had 4 miles til empty.

Could a very low gas level cause a misfire? I've googled around and seen a bunch of BMW related posts on this subject and was kind of curious if that could be what caused my code.

 

You could, but the car would be starving for fuel and running poorly. You'd need to run the tank near bone dry for that to happen.

Also, don't boost below 1/4 tank.

 

Thanks a ton for the info Joe.

I wasn't whipping, but I wasn't exactly cruising on the highway either.

By the time I got gas, I did put in 11 gallons so it was very low. Drove home from the gas station and then the next time I started it, I had the check engine light.

Regardless, Ive never let my tank go that low before and I'll be sure to not let that happen again.

 

2015 ST3 around 5000mi and I also had these codes come up with CEL light. It has happened twice so far. First time was the cylinder misfire and second was the random misfire. Both times it was determined by my ford dealer No Problem Found. He ran a complete diagnostic both times. First time he just cleared the code after the diagnostic but 2 weeks later it reappeared and then he cleared the code and performed some kind of factory reset procedure with calibration for engine misfire detection. Not exactly sure what he meant but he was working hard on it for over 2 hours the second time. It's been over a week and has not failed again. Will see what happens and report back if it fails again. Just like the OP mine ran smooth and no obvious symptom when misfire occured. The tech mentioned my second misfire was recorded when I was barely moving at 1mph.
I kinda thought it was from bad gas or something but he assured me it most likely was not that since the car runs smoothly. He was not sure what caused it except possibly not calibrated correctly when manufactured that's why he performed the reset and re-calibration. To be determined if this resolves the issue for good.

 

Thanks a lot for your post Noah.

It's good to know I'm not alone with this and its also interesting how similar our situations are... Right down to the mileage.

 

Update-

Left work an hour ago to an illuminated check engine light. Called the dealer that took care of me last time and they were able to get me in right away so I'm there again while they get to the bottom of the CEL.

I didn't have the code pulled prior to coming to the dealership this time so I don't know if its the same misfire issue, but I'll find out soon.

Fingers crossed that it's a simple fix

 

Update-

This time it was a cylinder 3 misfire. Last time it was cylinder 2 and random misfire.

Again, the car passed the tests and again, the car is running without any noticeable problems.

So, what they're going to do now is swap the plug and coil from cylinder 3 over to cylinder 2. The thought is, if the car throws another misfire and this time it's cylinder 2 instead of 3, they'll blame it on the plug/coil and go from there.

I mentioned that cylinder 2 was the misfiring cylinder last time but we are still going to go through with this swap and wait.

Whatever.

 

Do you get the CEL while driving? Or while standing, in neutral..

 

1st misfire CEL- When I first started the car in the morning.

Todays misfire CEL- When I first started the car in the afternoon after work.

So, both were right upon start up after the car had been sitting for 8 hours. Standing, in neutral.

your not going to want hear my opinion so I will keep it short. don't tune your car, leave it stock. i would advise against touching your car specifically at all, no mods no nothing. if your having these issues stock, I wouldnt touch the thing.

No worries there. I have zero urge and zero plans to tune or mod the car. That's not my thing.

 

your not going to want hear my opinion so I will keep it short. don't tune your car, leave it stock. i would advise against touching your car specifically at all, no mods no nothing. if your having these issues stock, I wouldnt touch the thing.

 

I'm asking because I'm having the exact same issues, car drives fine but I get misfire codes while standing in neutral (for a while). I think the dealer already replaced all Ford lists for misfire codes, I might get a new engine soon (under warranty).

 

How many times have you had a misfire code come up?

How many times have you been to the dealer for it?

 

So I can reproduce the problem basically starting up a cold car and leaving it running idle for up to 10 minutes. This way I get the CEL like 1 out of 3 or 4 attempts. I've been to the dealer with this maybe 6 times already, each time they replace something else but now I think they replaced everything Ford asks for for this code (plugs, coils, cables checked, compression test done, in tank fuel pump replaced, maybe something else I don't remember).
I'm wondering if dirty intake valves can contribute to this issue..

 

Boy, that's a lot of trips to the dealer. Too many really.

 

Yes. So I'm interested in the outcome of your issue as I did not have many other people with this problem.

 

Update.

Got out of work 39 minutes ago and was greeted with the CEL upon start up... Just like the last time this happened.

Drove immediately to my Ford dealer and am awaiting their word on how we are finally going to fix this.

Getting real tired of this. I am desperate for a fix.

 

@FordService

Maybe time to get Nick involved. Good luck!

 

I've been in contact with Nick. He's been a help for sure.

Just talked to the tech and the CEL was for the cylinder 3 misfire for the second straight time.

They've ordered a new injector for cylinder 3. It will get here tomorrow and in the mean time, I'm going to take a rental home.

 

Home now. Kinda glad that this third CEL was the same as the last one- cylinder 3 misfire. Really hoping that a new injector solves this issue.

Rental car is a 2015 V6 Mustang. When I was shopping for cars, I drove the ecoboost Mustang prior to getting in the STs and was pretty underwhelmed by the car. Good power, but it felt huge, yet tiny inside and the overall ride was very floaty. Also it was very hard to place the front tires while steering.

The V6 is more of the same. Incredibly floaty and it's still weird to just stare at the hood the whole time and have very little clue what the front tires are doing.

One thing to add- it rained a lot today. This V6 Mustang gets ZERO traction on wet streets. That rear end steps out with any throttle applied in a turn. I've driven rear drive before, but nothing I've driven was as loose as this. The all seasons on this thing have zero bite.

I miss my ST already





And oddly enough, I really didn't like the rear of the new Mustang, but it has grown on me a bit... it's a nice look to walk up to. Wide.

 

This V6 Mustang gets ZERO traction on wet streets. That rear end steps out with any throttle applied in a turn. I've driven rear drive before, but nothing I've driven was as loose as this. The all seasons on this thing have zero bite.

I do not think they have made a Mustang yet that gets traction on anything but dry pavement!

 

Mine waited until about 7000miles before my check engine light came on. It threw a P0303 and a P0316, the random misfire cylinder 3 and random misfires in the first 1000rpms. It’s been to the dealer 3 times now, the first two they hooked it up and nothing was wrong, no misfires. This last time they decided to take the coil from cylinder 3 and move it to cylinder 2 to see if the problem moves cylinders (thinking it may be a weak coil). So now I am just waiting for the light to come back on to take it in again. I am really hoping that they can find the problem because I do like the car, but the lifted F250 sitting in the showroom was looking pretty nice..........

 

I have the exact same issue with cylinder 3 misfire. Only happened on start up and only happened every couple months or so. I suspect a leaky injector.

Sent from my SM-G920P using Tapatalk

 

Wow, Jason and ecstasy, thats pretty wild. Us 3 have been experiencing IDENTICAL problems, right down to it being cylinder 3.

They even did the cylinder 2 and 3 spark plug swap on both of ours.

Wild.