Throttle body
 

. I highly recommend cleaning the throttle body then reprogram the position. There are some threads on how to reprogram using the key and gas pedal sequence. A master RR tech informed me of this and untimely saved me thousands of garage scams. Best of luck fellow Rovie

I would make the shop keep working on it until they get it right. $3000 is a lot of money.

Thanks for posting your update. That is very bizarre. I would have thought the shop would have tested the vehicle before you picked up. Either way they need to fix it.
what would the rear diff have to do with rpm fluctuation??

my 2005 still has this issue. Mine seems to do it also in manual mode but I would say it’s not as prominent in M.
I did change the pedal sensor…no change. This is an issue that a lot of LR3 owners seem to have but the fix remains elusive.
please post any updates.
I’m still leaning towards torque converter or transmission shift solenoids.

So what was the reason for replacing the rear diff?
Just curious as I had a rear diff fail, it was loud like a badly worn mud tire. Did not have an RPM issue with it.
Most Shops are going to work with you if there was really a mix up.

Hi and thanks for the interest. Despite constant research on the forums trying to troubleshoot the RPM issue and mentions speed sensors, torque converters, I have yet to find someone who actually fixed this problem, so when this professional and well reputed shop told me it was the rear diff who was I to argue. Their initial advice was actually to drive it until it got worse because it's expensive and they knew we are a non-profit with limited funds. I didn't want to do that because I didn't want the rig going down on the trail and the RPM surge is very annoying.

Now to be fair there was a "whirring" feel to the drive line that I associated with the RPM fluctuation, because I noticed them around the same time. I know trying to describe a driving sensation can be difficult but to try it was more something that you felt while driving then audibly heard. It felt like a periodic resistance that was cyclical. I associated this with the RPM spike because that is a periodic event too. The shop is saying they are two separate things and it needed the rear end, and that the whirring is gone now. I can't verify this as I wasn't the one who drove it home, a friend did, and he just told me the RPM spike is still there and brought it back to the shop. He's not familiar enough with the vehicle to speak to the whirring.

Funny thing is the shop is saying they can't recreate the RPM spike and they have driven 70mph on the highway for a long time. I had to tell them AGAIN that it happens between 20-50mph blah blah blah which makes me think they never diagnosed the RPM's in the first place, which is the main reason I brought the LR3 in to get worked on. So they have it and the saga continues. I told them I paid that enormous price believing they had fixed the problem I brought it in for, and to make things right. We'll see.

Hi, please read the other comment I just posted where I go into detail with this. You saying there was no RPM issue with your rear diff problem makes me think maybe they were two separate issues that surfaced at (or around) the same time. We have 3x LR3 and this one only has 108k while the others are close to 200k and they've had no diff problems. This one belonged to an older woman who had it regularly serviced at a dealership so weird the diff went on this one. We do wheel these rigs a lot now but don't abuse them or go heavy on the skinny pedal. My symptoms (that I associated with the RPM spike) were not audibly loud at all, it was more of a periodic drive line resistance that you felt, like an oblong sphere trying to spin in a perfectly round container.

Makes sense that a couple things could have happened at the same time. I ended up replacing my drive shaft when we did the rear diff. Found the carrier bearing rubber was bad also and didn't wish to take out the new diff, did not know that was an issue until we were in there.
I really don't think the diff issue would have been from you wheeling it. That's what these things are designed to do.
I can see the surging getting over shadowed at the shop with the noise those rear diffs make. Mine was quite alarming once I realized it was there. Sounded like a really bad worn mud tire. Yuck. I'm willing to bet the shop will work with you on whatever is found, if they are what you say they are that is. Those shops don't last long if they aren't any good or stand by their work.
Good luck man. Let us know how it works out.

Just got this from the shop
 

Have some data back from your tech.
It's extensive and I'll have all the notes for you on the paperwork to refer back to at a later time.
I'll summarize his findings.
He was able to exclude an intake leak, MAF, EGR readings etc which can all cause a surge feeling. There was way more testing here than just this but short is better here.

He monitored the data coming from the transmission and nothing telling there. All the solenoids are reacting as requested.
Interestingly he found a post on a tech page that recommended testing it in "Sport" mode and see if there was any feedback there.
He did and there are zero symptoms when in Sport mode.
What this tells us is there are a couple things that can be the cause.
It could have, as you suspected, internal wear on the converter, fins worn etc or the oil pump output is just not good enough to maintain converter lockup.
When in Sport mode the pressure is bumped so the symptom is not there.

As part of the 1st visit one of our recommendations was to get the trans service taken care of to make sure the fluid level was correct and of course the filter was good as improper fluid level can cause all kinds off issues.
Originally you opted not to do it then as we know we missed that and performed that service along with the other items.

I want to point out that the rear differential was never sold as part of the surging issue but when you and I talked we both decided that the rear differential was an issue that needed to be addressed sooner than later so we went down that path.
Now that it has been replaced that whining noise is no longer but of course the surging was not addressed here.
Also the transmission service was not the answer as the issue persists.

We submitted a tech support ticket to make sure our findings were good and they confirmed that the likely repair here is the transmission.


We work directly with ZF the original manufacturer of these transmissions and we are told this service runs approx $7300 (installed) plus taxes (exempt).
As the transmission service we performed was of no use here I feel that I should credit that entire amount (not just the $491 you paid) of approx $1500 towards that repair should you decide to do that.
ZF tells us it would take them approx 3 weeks to get the transmission to us for info.

I have to commend you, most people would have never picked up on that surging as typically it's not driven consistently at that speed but zoom past that to get up to speed on the freeway where of course it's not happening.
That's from the higher RPM which boosts the internal pressure by default.

This is a lot of info to look over and of course I'll not proceed without your approval.
We are taking off for the evening so lets discuss tomorrow.

*this is my notes on this; when he says the diff was “not sold as part of the surging issue” I’m going to call BS because they said the rig was ready and all done and never said the surging WASN’T fixed, when in actuality they never even knew it was there (besides my telling them when I brought it in and they dismissed it or thought I must be talking about the rear diff problem.”

Thoughts?