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Discussion Starter #21
With that stuck on, i'd also be cleaning up terminals. Not good ground etc could give your computer fits too. Seems a little knit-picky, but I always go after the little things first before spending money. Especially if I stumbled on something like a stuck battery terminal like you luckily did. Those stupid little variables are responsible for their share.
Thank you for the input. Battery terminals are very clean. It’s not so much of the cable being stuck but it is hard to pull off. I thought I had loosened the little nut as much as I could but I may have not. I have already gotten my battery and alternator checked and everything checked out fine. I figure that if a bad battery or loose cable would have been the issue, the battery monitoring system would have sensed it and something would have lit up on the dash. The truck cranks up fine with no hesitation.
 

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Discussion Starter #22
Thank you for the input. Battery terminals are very clean. It’s not so much of the cable being stuck but it is hard to pull off. I thought I had loosened the little nut as much as I could but I may have not. I have already gotten my battery and alternator checked and everything checked out fine. I figure that if a bad battery or loose cable would have been the issue, the battery monitoring system would have sensed it and something would have lit up on the dash. The truck cranks up fine with no hesitation.
To add some more info, since temps have dropped down to mid 80’s, the truck is idling superbly with ac on max. Rpms don’t dip when coming to a stop and all is good. Since my issue was there when the temps were in the 100’s, I started suspecting of the AC charge. Either that, or the min rpms underload need to be adjusted. I’ll ask dealership to check both the tube and ac compressor. I can’t think of anything else
 

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Hi Brian, I meant to ask earlier if your truck has always done this since new or if it started doing it later on after you bought it. Thanks!
I don’t recall it doing it until late this summer .
Perhaps around 20-25k miles .

I’m not to concerned personally


-Brian

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18 Lariat 26,000 miles. Mine does exactly as you describe as well. It nearly always has a very slight low idle (only I might notice it) when coming to a stop but it’s always much worse when the AC is cranked and the engine fans are on high - it’s always worse when the outside temps are very hot. I’m just a little north of you near Atlanta so it’s been running fine the last week or two.

Mine had done this since new but like I said not all the time is it bad enough to worry about. I’ve had the truck at the dealer for it once but they found nothing. Truck is perfect otherwise.

I ran 87 fuel for probably the first 20,000 miles then switched to exclusively 93 the last 6,000. No difference. Once the shake was terrible like you described. I was in north Georgia in the mountains. Truck had been sitting all day. It was mid 90’s and very humid. Went to leave the parking lot and truck was shaking so badly I thought something was coming apart. No noises but idle was about 450 rpms when at a stop. Truck ran fine once going down the road.

One thing I have not seen mentioned. If you put the truck in neutral the idle will immediately return to normal and the shake goes away.


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That last mention of putting it into neutral.....

That's interesting.

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Discussion Starter #28
18 Lariat 26,000 miles. Mine does exactly as you describe as well. It nearly always has a very slight low idle (only I might notice it) when coming to a stop but it’s always much worse when the AC is cranked and the engine fans are on high - it’s always worse when the outside temps are very hot. I’m just a little north of you near Atlanta so it’s been running fine the last week or two.

Mine had done this since new but like I said not all the time is it bad enough to worry about. I’ve had the truck at the dealer for it once but they found nothing. Truck is perfect otherwise.

I ran 87 fuel for probably the first 20,000 miles then switched to exclusively 93 the last 6,000. No difference. Once the shake was terrible like you described. I was in north Georgia in the mountains. Truck had been sitting all day. It was mid 90’s and very humid. Went to leave the parking lot and truck was shaking so badly I thought something was coming apart. No noises but idle was about 450 rpms when at a stop. Truck ran fine once going down the road.

One thing I have not seen mentioned. If you put the truck in neutral the idle will immediately return to normal and the shake goes away.


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Hi Robbie,
Thank you for sharing this information. Looks like you and I have had very similar experiences. My truck too, shook so bad one time, my stability control light came on. I thought the truck was going to fall apart as well. Other than the rough idle and this one time severe shaking experience, I've enjoyed my truck a lot. Since the temps came back up to low 80's yesterday, I started to feel the shake very slightly again throughout the day. This morning on the way to work, as always, the truck idles great. I have to switched to 93 octane with no change. As you said, it is worse with AC on and worsens with increased AC fan speed and higher outside temps. Seems to be a widespread issue with 2018 F-150 3.5 ecoboost. Seems that most folks who have reported on the issue, have about 22,000 to 28,000 miles on their trucks. It'll be interesting to see if those with less mileage see the same symptoms later on. I have not done the shift to neutral thing since my truck smooths out within a second or two after the rpms dip immediately after stopping. Sometimes I wonder if this could be a torque converter issue. I don't know though, I am not very mechanically inclined. I have towed around 5,000 lbs with my truck and all was wonderful. My truck is an 08/18 build, it is not a 2017 build. I may be wrong but I wonder if enough people reported this issue, that Ford will look into it and figure out a solution? I hope we see a TSB out for this in the near future.
 
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