Runs rough and sometimes shuts off

Tiny
MATT-_BROWN
  • MEMBER
  • 2019 FORD F-150
  • 5.0L
  • V8
  • 2WD
  • AUTOMATIC
  • 36,500 MILES
My truck (XLT model) starts and drives fine, but one day I was going through Atlanta when I got to a stop light and it just shut off on me and I have noticed it a lot more since then and it just idles really rough and sometimes cuts off on me. I took it to the dealer and they said I had a bad coil on 7. So they replaced it and it still is doing what it was before. I have no check engine light on.
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Thursday, March 19th, 2020 AT 3:50 AM

13 Replies

Tiny
ASEMASTER6371
  • EXPERT
Good morning,

If they saw the misfire at the cylinder, do you know if they did a compression test?

https://www.2carpros.com/articles/how-to-test-engine-compression

Did they replace the plug as well?

The check engine light will come on as soon as it misses the number of times for misfires.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Roy
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Thursday, March 19th, 2020 AT 5:14 AM
Tiny
KASEKENNY1
  • EXPERT
So I am curious if they gave you any information about why they found the coil was the issue? Clearly if it is running rough we would think a misfire is the issue but on a 2019 they have really good misfire detection. So the fact that it is not setting a misfire code, I suspect we have another issue that feels like a misfire. Something like a vacuum leak.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

However, again due it being a new vehicle we have really good system monitoring so even a vacuum leak should cause the PCM to set a code. This is leading me to think we have a sensor issue like a MAF or IAT that is wrong throwing off the air/fuel mixture causing a rough running condition.

At this point, do you have any way of monitoring o2 sensor data to see if the engine is actually running rich or lean when this happens?

If not, we clearly need to get it back to the dealer. I would suggest taking the adviser or tech for a ride with you to show them what it is doing.

Let me know and we can go from there. Thanks
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Thursday, March 19th, 2020 AT 5:25 AM
Tiny
MATT-_BROWN
  • MEMBER
I don't have a way to monitor that, but it was under warranty and they gave me the run around and said that I told them it was misfiring and that was it so they "fixed" it and didn't check for anything else. Normally if it was a vacuum leak you could spray brake cleaner and find the leak with the engine revving up right? Honestly I have just been trying to figure it out because it's bugging me and I need a good running truck. Thanks for the input. I am going to put a scanner on it today and see if there is any codes that pop up even though the light isn't on.
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Thursday, March 19th, 2020 AT 12:09 PM
Tiny
ASEMASTER6371
  • EXPERT
Did anyone check the compression when they had it?

I doubt you will see a code since the light is not on.

You need to go to mode 6 on your scan tool to see which cylinder is not firing.

Roy
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Thursday, March 19th, 2020 AT 12:15 PM
Tiny
MATT-_BROWN
  • MEMBER
They never told me they did a compression check, so I am not sure if they did or not. But I might be able to get one done soon.
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Thursday, March 19th, 2020 AT 12:44 PM
Tiny
ASEMASTER6371
  • EXPERT
I would get it checked. That is the first thing they should have done when you presented it to them.

Roy
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Thursday, March 19th, 2020 AT 12:50 PM
Tiny
MATT-_BROWN
  • MEMBER
I'm going to try to run a compression test on it when I get home tonight and I will let you know what the PSI is on each one.
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Thursday, March 19th, 2020 AT 3:30 PM
Tiny
ASEMASTER6371
  • EXPERT
Sounds like a plan.

Roy
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Thursday, March 19th, 2020 AT 3:32 PM
Tiny
MATT-_BROWN
  • MEMBER
I was going to do the compression test and I took one plug out and had oil all over the threads so hopefully it should be covered under the 5 year 60,000 miles power-train warranty. I'm just going to let the dealer figure it out and save me some trouble.
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Thursday, March 19th, 2020 AT 6:42 PM
Tiny
ASEMASTER6371
  • EXPERT
Good idea. I would request a free rental car from them for the duration of the repair.

Roy
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Friday, March 20th, 2020 AT 4:45 AM
Tiny
MATT-_BROWN
  • MEMBER
I tried that last time and they said they didn't have any and couldn't get me one.
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Friday, March 20th, 2020 AT 5:17 AM
Tiny
ASEMASTER6371
  • EXPERT
They can do it. It is just a choice they make. Not good for customer service when they decline this.

Roy
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Friday, March 20th, 2020 AT 5:24 AM
Tiny
KASEKENNY1
  • EXPERT
Just a suggestion after reading the last few posts from you and Roy. Not only do they want to do what Roy said but depending on the results they need to find where that oil is coming from. Assuming they replaced the plug when they did the coil, for it to be oil fouled this soon shows a pretty good leak. I would leave that plug in there so they can find it and make sure they understand that it stalls as well. A misfire on one cylinder will not cause a stall which is why I am thinking there is a larger engine issue.
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Friday, March 20th, 2020 AT 7:31 AM

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