Have been experiencing noticeable jitteriness in accelerating from a dead stop that begins somewhere near the 1600RPM point up to 2500RPMs and sometimes above. Sort of a roughness to it. Car drives smooth otherwise and still getting expected gas mileage. No warning lights have illuminated to date.

Anyone have similar experience and have a sense of what may be occurring?

 

It would be good to know what codes are being throw.

 

This sounds kind of similar to a vibration I'm trying to also diagnose. It seems to be "moderate" acceleration (especially uphill) from about 20-35mph and about 1500-2800rpm. Completely gone after 30-35mph, also doesn't show up at all if I accelerate a bit more aggressively from a stop. But I feel it in the center of the car and though it doesn't shake the steering wheel I can feel the vibration there as well.

I haven't had any codes thrown that my IID is picking up so I'm not sure where to start looking honestly.

 

Start with something simple. Get som BG platinum 44K injector cleaner. use 2 cans and run 2 tanks of gas. Check for codes. When was the last time you changed the air filters? Whats the mileage? have you changed the spark plugs? How frequently do you drive the vehicle, and for how long. I.e. do you run a few errands then let it sit. or are you pulling some highway miles and running it at temper stretches of time?

 

I can’t speak for the OP but in my case I did run one can of BG44K through my tank a couple weeks ago, I replaced all air filters 3 weeks ago and I’m unsure of the spark plug condition (only had the truck a month so far. Mine’s at 143k presently and is right now mostly used for around town driving with a few longer (50+mi) drives on occasion. But it is being driven most every day.

Should I run an additional can of BG44K? I only thought to run one. Though interestingly timing wise right after running it through the tank and having run the whole tank, after that next fill up my fuel supply manifold broke and it dumped the whole tank while driving. But that’s a separate topic

 

Same issue. I've been diagnosing it for months. What I've done:

1. Replaced Air filters
2. Replaced spark plugs
3. Smoke tested for vacuum leaks
4. Removed and cleaned fuel injectors by hand
5. Ran several cans of BG 44k through
6. Used BG EPR before latest oil change
7. Cleaned MAF sensors
8. Cleaned throttle body

No codes, ever, but I do get the occasional stability control / HDC / parking brake lights when temps are below freezing. Turning on and off the car resolves this.

I've read all my values including fuel trims and air intake. Fuel and air mix is good.

Next possible attempts:
1. Shudder fix in the transmission

What I first thought might be a fuel / air issue I'm beginning to think is the torque converter. When I run in sport mode the issues mostly go away.

Any thoughts on any of the above?

 

Yeah I’ve been wondering if it’s transmission or differential related. I’ve ruled out wheels/tires as those just got replaced and nothing changed. I also have had no codes or signs of a problem when I scan everything.

To my knowledge my transmission fluid hasn’t been changed but the torque converter is an interesting possibility.

Interestingly my dad’s ‘11 L322 HSE has the same vibration in the same conditions but his is a bit more noticeable. He didn’t notice it, but I picked up on it immediately after driving his RR.

 

I don't have a noticeable "vibration" but a hesitation in acceleration between 1200 - 1800 RPMs. Makes it feel like it's choking. Like it's not getting enough air in the mix. But all my values read normal.

The other possible culprit is my O2 sensors which could be giving misinformation and creating a lean/rich fuel issue without warning. But I haven't bit the bullet to replace those yet as they seem fine.

Once I try the shudder fix I will see what happens.

As it relates to the transmission fluid, LR built the transmission casing so that you would have to cut it off to remove it and install a new 2 piece system to change the fluid. The fluid they put in is supposedly lifetime fluid. I've talked to a few techs that say, by no condition, should you try to change the transmission fluid as it has blown the transmissions out in the past. Weird admission in my opinion.

I would love to hear if others have found a resolve. Or if any one attempted to remove the transmission casing and change the fluid and install the new 2 piece system like this: https://www.roverparts.com/transmission/kits/ATFCKWFL/

 

If also “consuming” oil, about 1/2 qt every 5000, I’d propose changing the PCV valve.
Not only did my oil consumption reduce but acceleration performance increased as well.

In this new “watch the sensors and modules” world, we really have been tuned to watching for codes.
So I really appreciate the comments of “start with something simple” as @jeffh suggests.

That transmission of ours is very robust. whether the 6hp or the 8hp.
But, as the manufacturer of the transmission attests (ZF), it needs a regular service. You don’t need to go crazy with multiple changes or a complete flush, like many do. As ZF prescribes, a regular fluid change and filter change is sufficient.
I do mine every 60-75k kms.

As do the diffs and transfer box need a regular fluid change.

But ”Jitteriness” to me is an engine related outcome as opposed to a driveline issue.
And I hate to say it but for our internal combustion engines you’ve only missed two other components that didn’t exist in the rotor/points/coils days… coils and injectors.

 

Have you looked at the driveshaft? You'll get some shudders and judders if the center bearing rubber has worn out, and when I went to change my center bearing I found my rear U-joint and center CV joints were notchy feeling. Changed my driveshaft and it's been smooth since.