Shudder/Hesitation when cruising in 6th gear/Low RPM

[baws22489]

Hi, I'm new here and purchased a 2016 SHO in September. I love it but it has been driving me crazy. When I'm driving and the car is in 6th gear and the RPM's below 2k, when i give it a little gas to speed up, i can feel the car hesitate/jerk some. This happens just about all the time regardless of weather. If it downshifts the car picks up speed fine.I tried different levels of octane gas 87,93(always use shell) but its still there. The car has less than 4k miles and I'm not mechanically gifted. I have read that some Ecoboost motors get oil or sludge in the CAC and it needs to be drained. If so im not capable of doing that and wondered where i should look for help. The motor is stock non PP package and i don't drive it hard. So wondered why this would happen in the first 2 months of owning. If i drive in Sport mode from what i understand stays in 5th gear, the car runs great but I'm not sure if i can do that all the time as i put 90 miles a day going to work.

Sorry for so many questions and thank you for any help,

Steven

 

[sholxgt]

I have the exact same issue.  I believe the problem lies within the torque converter, but have not found a solution.  Car has been to two dealerships and been driven by several mechanics.  None are willing to help because they are not certain what is causing the issue and it's mild.

Major problem for me is, once I tune with with any of my SCT based tunes, the stutter/jerk spreads like wildfire to include all gears and speeds up to about 2,800 rpm.  With any tune, once under load, the same stutter/jerk becomes unbearable.

Curious question...do you live in a hilly/mountain area?  I do which makes the problem significantly worse.

My advice to you is make sure that you either get the problem resolved or don't waste your money on an SCT based tune.  It will make the problem MUCH worse.

Edited to add...if you search here and on shoforum you will find others with the same issue.  So far, all reports have been from non-PP cars and it centers around 1400-1500 rpm in 6th gear.  That is if untuned.  Once tuned it spreads.  No one has posted a fix except one person that found a Livernois tune to solve his issue.  Not sure it his was the same problem though.

 

[SHOdded]

If it happens going uphill, there is a tsb for the PTU

 

[baws22489]

I live in Southern Maryland on pretty flat surfaces and drive to DC everyday. Mostly back roads and 2 lane roads. Today i drove on the Beltway to Tysons Corner and it seemed worse because i was doing more cruising at high speeds. I just shifted down to Sport mode as it was frustrating.

 

[Vortech347]

Mine does this exact thing.  It's not so bad in my native Utah air but down here in California I'm REALLY feeling it quite badly.  Going up steep grades at lower speeds 60-65mphish when it loads up in 6th its down right nasty.

Flat surface, it's fine. 

 

[SHOdded]

I would have the PTU checked.  The TC also has been known to go bad, but let's pile on the scapegoat first

A proposed solution by LME for trans misbehavior is adding 1/4 quart of fluid past the FULL mark.  Helps prevent cavitation.

 

[baws22489]

Mine happens on flat surfaces and up hills?

I always take my vehicles to my local Ford dealer to get the "works" done every 5k miles, so if i ask them to check the PTU they should know what that means? Sorry i ask stuff like that but i have no idea what a PTU or TC is and I'm about to google it!

Last questions, if the PTU or TC are having issues, would it only happen in 6th gear and drive mode as opposed to 5th gear and Sport mode?

 

[derfdog15]

The PTU is part of the AWD power transfer system. TC is torque converter I believe. The torque converter locks and unlocks depending on RPM, which is a function of gear and speed (RPM). So that is definitely reasonable that it would go away in 5th in S, as RPM is held higher in S, thus the converter is most likely locked up.

Along with that, each gear has a different ratio related to engine speed vs. RPM. while 5th and 6th are both Overdrive, the ratio is different, so RPM at the same speed is different once again.

 

[sholxgt]

My PTU tested fine.  I checked it myself also and found zero slop in the driveline.  Could still be the problem for others though.

I had a tech do a drive along with his test equipment hooked up.  He found that as soon as he commanded 100% lock from the converter at low rpm, it would go into the severe stutter/shudder.  But, that doesn't necessarily mean that the problem is the converter itself.  It could just be the result of low rpm with high load.

Hard part is getting them to do anything about the issue.

 

[SHOdded]

The TSB I was referring to ...  Yes, the dealer should know the issue, but never hurts to have the TSB in hand to point out to them, if you get pushback.

Try the little extra trans fluid first see if it helps.

 

[baws22489]

Thanks for all the suggestions and help. I went down to check the trans fluid and couldn't find the dip stick. So got the manual out and see that i have to remove the air filter to even check the levels or add anything. I will wait till this weekend to try that.

I will let you know if adding 1/4 quart Motocraft mercon lv atf helps.

thanks again

 

[SHOdded]

:thumb:

 

[dubcitySHO]

So happy I stumbled onto this thread!  Another example of this particular issue on my vehicle as well, 2012 SHO with 85k on the clock. 

Are any of you (tuned) gents experiencing RPM fluctuations during acceleration before/during the shuddering?  I also believe the problem lies within the TC, as opposed to the PTU, as my fluid changes yielded nothing out of the ordinary although I did not send samples in for UOA. 

 

[Vortech347]

Brad made some adjustments in my tune to encourage the 5th gear downshift with high load a little sooner.  It make a very nice difference.  I think he made some TC adjustments too.  Hopefully he see's this thread.

 

[sholxgt]

So happy I stumbled onto this thread!  Another example of this particular issue on my vehicle as well, 2012 SHO with 85k on the clock. 

Are any of you (tuned) gents experiencing RPM fluctuations during acceleration before/during the shuddering?  I also believe the problem lies within the TC, as opposed to the PTU, as my fluid changes yielded nothing out of the ordinary although I did not send samples in for UOA.

Yes, tomorrow I will post pictures of my logs showing the rpm fluctuations. They are occurring even with AJP's excellent attempts to correct. He even went as far as to use the tune from a different strategy to no avail.

Stock my car is liveable. Tuned it is not an enjoyable vehicle.

 

[dubcitySHO]

I will have to drop Brad another email perhaps on this issue.  If he can tune out some of the tendency for the engine to lug without downshifting it may help.  At least with my vehicle it def seems like that's when it's most prevalent. 

 

[FoMoCoSHO]

Another option would be to pull that left lever when you want to accelerate since in D it will return to normal shift schedule without further input.

Obviously not a fix but it is a simple workaround till someone figures it out.

 

[dubcitySHO]

Another option would be to pull that left lever when you want to accelerate since in D it will return to normal shift schedule without further input.

My paddles are non functional in D on my '12 although the '13+ guys will benefit.  I have bumped down into M and used them to keep RPMs up in certain situations though.

 

[sholxgt]

Another option would be to pull that left lever when you want to accelerate since in D it will return to normal shift schedule without further input.

Obviously not a fix but it is a simple workaround till someone figures it out.

With the stock tune, I can put it in S mode and live with the higher rpm and lower fuel economy that comes with it to avoid the 6th gear stutter because it only occurs below about 60mph.  If tuned, the range of stutter expands too much for that to be an option.  It stutters even when accelerating at 70+mph on the interstate. 

At the beginning of each of the logs below you can see the parameters that are funky during the stutter.  Note the rpm variation and torque converter functions.  Boost included to show that I don't believe it is related to the issue.  Other motor functions appear normal as well.  I believe mine to be converter related.  The solution is likely a new torque converter, but I don't know how to get a dealer to spring for one.

Note that when the converter goes to 100% lock, the rpm variance diminishes greatly.

That all being said, I'm not 100% positive that it's the torque converter.  The thought of it possibly being LSPI from boost coming in at such a low rpm with the onset of load seems to be a possibility as well and would explain why the car is worse tuned than it is untuned. 

 

[Vortech347]

Another option would be to pull that left lever when you want to accelerate since in D it will return to normal shift schedule without further input.

Obviously not a fix but it is a simple workaround till someone figures it out.

The problem I ran into when doing this is the transmission would go back into 6th. So I had to lock it into sport on the big hills.