2014 Explorer Sport Hesitation/Bucking

[SHUMAX]

102,000 miles. I always run top tier fuel of at least 89 octane - normally 93. I also change the oil every 5,000 with synthetic fill and an OEM filter. I have an AirRad air intake on the engine. I give it a nice "Italian tune-up" once a week when it's been warmed up for a while.

Over the last 20,000 miles, I've noticed what follows to be getting worse. As I accelerate, gently, in 6th gear from 50mph on up to 70mph - without letting the vehicle downshift, it misses and bucks. I can "feel" it in the gas pedal, steering wheel and it makes the truck shake a bit. I can almost picture the engine rocking on it's mounts.

If it downshifts, it is smooth and there are no issues. It's only when I accelerate in 6th gear in that speed range. Also, if I hammer it and let it run up to redline, I can feel it missing just a bit (no matter what gear) above 5,000 RPM as it pulls.

The air filter is clean, there are NO codes and the plugs were swapped out 5,000 miles ago. No change. I'm starting to get concerned it's carbon build up from the DI design.

It goes in today for this and strut mounts. Any thoughts?

Shumax

 

[Odrapnew]

My wife’s CX9 was acting very similar, but hers was resolved with new plugs.
It would buck pretty hard in 6th gear on the freeway under moderate acceleration.
No engine codes.
It would go away when the torque converted unlocked or it downshifted.
I could get it to happen in other gears if it was low rpm and moderate load.

I purchased a Bluetooth OBD2 reader and checked for misfires.
I was able to watch the misfire count increase on a couple of the cylinders(one was worse than the other) when the bucking would happen, but it still wouldn’t register a code.

I replaced the front 3 spark plugs(they only had about 50k miles on them) and it went away. One of the front cylinders had the biggest misfire count.

Possible that one or more of your coils is going bad.

One other thing that I did was slightly stretch the spring inside the coils before I put them back on. I just took a needle nose pliers and pulled on the spring a little bit. Not sure if that did anything, but it was a “fix” for a similar issue on my old car as well.

 

[peterk9]

Unless you posted this issue before in another thread, I recall reading a post with the same issue. Hesitation in 6th gear but fine once it downshifts. Have not been able to find that post. Good luck.

Peter

 

[SHUMAX]

I likely have mentioned it before. Not sure. I took them for a ride and they felt it but sort of said it is what it is. The brakes are bad - warped and, when hot, shake like crazy. Strut mounts and struts too.

See how it goes!
Shumax

 

[KayGee]

Didn't you just have a bunch of stuff done not long ago when you were on vacation because of misfire stumbling/bucking? You should probably consider a scan tool that can graph misfires or get a OBD dongle and forscan to watch misfires, fuel trims, and other PIDs to trace down your problem.

Front end shake under braking can also be caused by worn suspension components (inner and/or outer tie rods - basically car will track fine under power, but shake under braking and feel like bad brakes) - just something to check.

 

[SHUMAX]

Yup, that was me on vacation. That ended up to be a cat and plugs, they said. No CEL since then so I suspect the CAT was to blame. I should get a scan tool. Suggestions on an economical option with in iPhone 7?

I am so intune to this generations front suspension I could write a book. In fact, I have on here over two explorers in this generation. After control arms and sway bar links, I am certain it’s strut mounts. Will replace the struts, too, given the mileage.

The brakes have too much disc transfer from the pads and warp after being warped up - mostly rear, but front, too.

Should know more tomorrow.

Thanks for the input!
Shumax

 

[SHUMAX]

Got the vehicle back. I attempted to duplicate the "missing" and it did do it some, but not a lot. The tech said he sort of felt it, but nothing real obvious. That's about how it goes for me. They looked it over and said they didn't see anything wrong - plugs looked fine. I did get new struts and strut mounts and they resurfaced the rotors as they had pad build up on them that was causing a shimmy at high speed (heated) braking. That popping in the front is gone and so is the brake shimmy. So, a sort of "win" for me.

For grins, I bought one of these: https://www.amazon.com/gp/product/B0091DJWV0/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

I have a three hour drive on the highway tomorrow and plan to watch for misfires on the scanner and log them. I just need to figure out how to use it quick!

Shumax

 

[kdog]

Hi Shumax,

I'm now experiencing the same symptoms at 114K miles. Were you able to determine the cause?

 

[SHUMAX]

Spark plugs. It helped but it came back 10,000 miles later. I gave up and ignore it, sadly...

 

[kdog]

OK, thanks. I'll get it in the shop next week and see what we can learn.

 

[MtnCar]

I have a similar issue with my '13 Sport. Happens around 60-65 mph going uphill on the freeway. If I shift down the shaking/lunging goes away. No CEL codes or any engine issues with regular driving. As troubleshooting steps I have replaced plugs, cleaned MAF and other sensors, replaced air filter. I do not think, in my case, it is not a misfire issue. It seems like something mechanical almost like the leverage while in top gear is causing a harmonic of some sort at that speed range and load. Wondering if firmer engine and/or transmission mounts would resolve the issue?

 

[kdog]

For me it seems more tied to load and low RPMs - uphill or accelerating between 1500-2000 RPMs. Downshifting will help as the RPMs will pass that low point. I've seen and had mentioned to me that the catalytic converters may be the cause.

 

[MtnCar]

For me it seems more tied to load and low RPMs - uphill or accelerating between 1500-2000 RPMs. Downshifting will help as the RPMs will pass that low point. I've seen and had mentioned to me that the catalytic converters may be the cause.

Seem like the same thing I am experiencing. Following to see what you find from shop visit. If it is the cats it may be a good excuse to replace with aftermarket catted downpipes since I already have a tune. Livernois Motorsports

 

[kdog]

Picked up the truck today - #2 cylinder coil was shorting and plug was fouled. Replaced #1 - 3 coils, since they had everything open and accessible, and all plugs. Took it for a spin on the hills - problem seems resolved. I'll keep tabs and let you know if it changes.