Hello all. I hope this is the right place for this since I just sign up and am in desperate need of some help.

I have a 2017 Ford F150 Lariat with the V-8, 6 speed transmission, and a towing package that I bought brand new off the dealer lot in 2017. About six months ago or so I started feeling a “shutter” at speeds of around 60 miles an hour. The “shutter“ feels like a trailer hitching type pullback however, I do not have a trailer attached to it. It also only happens when I take my foot off of the gas – kind of like when you’re trying to maintain a certain speed. It does not happen under acceleration or deceleration.

I took it to the dealership around the corner and of course on the test drive, we could not feel the issue. The service advisor stated that if there was no check engine light on, there was not a way for them to find an issue. I took it home drove it for a while and I started to feel this “shutter” at lower speeds.

I took it to the dealership that I bought it from, took the technician for a test drive and he felt the “shutter” right away. He stated that it was a torque converter issue. I had it replaced, however it still is an issue.

I took it to an independent mechanic who is a family friend, and he thought that it was some type of unbalanced tire, a misfire, or a fuel injection issue, but he wasn’t sure. I needed new tires anyway, so I took it to the dealership around the corner got brand new tires, however I still felt the “shutter“.

I took it back to the dealership around the corner for them to look at it. They had it for several days, and of course they could not replicate the issue. When I went back to pick up my truck, I asked if there was someone that could ride with me so I can show them the problem. The service manager and I went for a ride and we felt it right away. The service manager called the shop foreman to go for a ride and we again felt the issue. The foreman asked to drive my truck to “perform some diagnostic tests“. While we were driving he felt the “shutter“, he then put the truck into neutral while the shutter was happening, and the shutter went away. He said that it was a possible misfire in the engine, and he would go cylinder by cylinder to try to fix the problem. I was also told that they could not check the torque converter because it was replaced by another dealership and they could not “touch it.”

I had not heard anything back from them until today when I asked them for an update. They stated - "the lead technician has changed around coils and plugs, tested in different positions. There is no change. This is going to be deemed as a normal operation characteristic of the vehicle. No further repair to be made." And that, "the technician went above and beyond to make sure there was not an issue with the engine or idle. The other technician had no concerns with the transmission. I do not have anything else that I can do for the vehicle."

I know it’s not just me when I say that I know this is not normal operation. Like I said I bought the truck brand new off the lot, it has only been an issue in the last six months. I need someone to please help me figure out what this problem is. Thank you in advance.

 

You are in a tough position with trying to identify a problem without clues.

Short of throwing parts at it, there isn't much to do without having the computer help pinpoint the concern.

Like they have done already with coils, that seems to be eliminated. Maybe it's just time to freshen up the plugs with a new set of Motorcraft plugs.
Please though don't go out and purchase a set of coils to chase this problem- biggest waste of money. Also in the wasted money category, don't touch your injectors or have them 'cleaned'.

Depending how much carbon inside the motor, could have a valve not properly sealing or a bunch of other random stuff. A code would help isolate a specific cylinder problem then one could swap coils to move the misfire, but no code present. One could also change the plug in that cylinder.
My first thought was a misfire but you said it isn't happening under a load which is when minor misfire "shudders" are felt.
Can you duplicate this in any gear -you're on the highway and feel it -will it happen again/continue if you shift to 5th and maintain speed?

I actually credit your service department for looking into as much as possible without simply throwing parts at it or telling you you 'probably need an injector clean' or "8 new coils to be sure we found the bad one".

 

It certainly sounds like a misfire issue. Hard to trace down without a CEL or access to IDS to run a misfire monitor though. Did they just move around your plugs and coils? If they are moving around a faulty one, of course the problem will still occur as its still in there, just a different cylinder. Start by replacing your spark plugs. Use Motorcraft and make sure to gap them correctly. When you pull each coil off to get the plug out, look at each one closely for Carbon Tracking. If you see any at all, replace that coil as well.

 

Can you duplicate this in any gear

To answer the question, yes I can duplicate this in any gear as did the shop foreman on our test drive.

 

[QUOTE=medicman2004;6896510]That could potentially rule out a misfire under load then. Lot of times those little glitches are apparent while in O.D. trying to climb a hill and not force a downshift.

Sounds like a challenging one to troubleshoot.
How many miles on the truck?

 

I think you should have the dealership that charged you for a torque converter take another look. They clearly threw parts at it that you paid for and it didn't solve the problem. So what are they going to do for you now? Taking it to 18 other places to have them look at it, you're just going to keep throwing money at it.

 

How many miles on the truck?

About 40,000

 

I know you said you had converter changed already but I had a customer with a 17 that had about 80k on it and it was doing something similar. I serviced the trans and added 2 of these https://www.lubegard.com/products/isf/ . Its got 150k on it now and still running strong. It would be worth trying
Mitch

 

Definitely sounds like a misfire. Had this on my 2008, swapped out plugs and coils, my truck ran like new.