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Odd Defender behavior Offroad in 4L/Mud Ruts, Also an air suspension error msg
Had the 110 up in the mountains yesterday. Performed great. 2 notable things happened with the Defender, and I was wondering if anyone else w seat time can confirm #1 below as normal. Background, I have lots of experience in most all LR platforms off road, and own a couple now, so I know what I'm doing but by no means camel trophy ready.
Car = Stock Defender 110 X P400 with the factory AT tires (Adventure not Duratrac) and 1.5" lift rods.
#1 -- In slushy snow mixed with lots of mud, going straight on a flat area so neither up or downhill, as I gave it gas the truck was revving alot (3000-4000 RPM), almost like the transmission was slipping.
What was weird is there was NO wheelspin at all (I looked out window at front and rear drivers side wheels) or even "stuttering" (like when it's finding traction which is what I expected based on experience with more modern rovers with terrain response).
Settings - I was in 4Lo, Mud Ruts mode, ATPC on/HDC on but not being used.. Is this almost "slipping transmission" feel normal? I wonder if this is just me learning a new generation of LR terrain response equipped vehicle.
I literally thought I'd lost drive and had a mechanical problem. It crept forward slowly revving high with wheels slowly turning. This continued until I turned off the truck, put it in N, 4 High transfer case, then back in 4 Low. By then I was in a different spot of the trail.
So is this "viscous" feeling to throttle input is just what a Defender does in the mud mode / 4Lo - on a very slippery surface. Is this normal? It was as if the auto transmission was slipping or you were massively slipping a clutch in a manual transmission car. The car would not move forward unless I gave it a ton of throttle (with according engine revving quite a bit more than I’d expected)
Here's a pic representative of the surface when this was happening.
#2 -- "Suspension will raise when system cooled". Most of the day, I remained in standard ride height.
A few times I changed suspension heights from standard to Offroad 1/2. Mostly to see how ride quality was affected inside. I was not "over working" the suspension really....
About halfway thru got this error message "OK to drive with caution Suspension will raise when system cooled". This after I got out of the Defender to take pics (so when I got back in and drove off it tried to raise me out of auto access height, so it was refusing to raise).
Yes, I've seen this sort of message on every other Rover... its usually when the compressor gets tired or when I'd go up and down in the driveway more than a few times in a row. When this message was on, pressing the height selection buttons did nothing in the upward direction so annoyingly I was stuck in access height (fine for this trail and I do have a 1.5" rod lift).
Note to self: turn off auto access mode when Offroad.
So I rocked it in access height for a good bit of the trail. An hour later I stopped and it was back in normal height and operated properly. Dealer did just replace the voss fitting on the pass side front upper strut (leaking slightly) last week but -- I must have a leak that's happening when articulating the suspension, or a software problem, am I right in thinking I have a leak somewhere in the system?
Otherwise suspension felt normal, no issues.
What you describe I think is normal. I think maybe I would try it again NOT in mud ruts mode and see if the same thing happens, to the degree it did. I ask because being in MudRuts places the system at an elevated point of base RPM from which the traction control system auto-cycles (or so it seems to me). Mud Ruts assumes a lot of energy is going to be spent to clear the deep mud, snow or sand out from front of the wheels.
You did not have this situation, instead you had a very firm but very slick surface (or so I understand from the photo and your description). If this is the case, I would have put the system in grass/gravel/snow mode in LO range and ATPC activated. Do you have the locking rear e-diff? I ask because my understanding of the capability of that differential is that it must behave differently than a non-e diff rear end. Even when in ATPC mode. What you describe leads me to suspect you do have the locking ediff. (just a guess)?
I would also retry the situation with ATPC not selected. I expect the behavior at the tires will be different.
I think what you describe is what should happen in ATPC with a locking rear diff on a hard, slippery surface with absolutely zero traction available at any wheel -- or so I have experienced and suspect. The action you describe in the last sentence -- as you shifted out of 4LO, etc. occurred because your departed ATPC, in my understanding (I am guessing a bit).
I notice you noted high revs. -- my experience in a P300 vehicle suggests to activate the logic in Mud Ruts to move forward you must have been at 3200 rpms (or thereabouts). To do the same in grass, gravel snow mode, you would be at right about 2300 to 2500 rpms.
The nature of the ediff on the Defender is unlike any previous generation. JLR products (other than the Evoque) including the Discovery 4, RR sport, older RR, etc.
On point 2: yes, if things are as you describe, and for instance you were not going at high speed on a bouncy road, you may likely have a leak in the air suspension system, somewhere.
Enjoy !!
Last edited by TrioLRowner; 06-06-2022 at 03:08 PM.
As far as the engine revving but little motion and no wheelspin, I believe you experienced exactly what JLR intended to happen in M/R setting. Their goal is to tread lightly in slippery situations, and I've been AMAZED at how my truck can get out of a soupy mess with so little damage to the landscape. And that seems to be because it simply doesn't bother spinning any tires unless and until there is no other option. I had this "idea" confirmed in November at Asheville.
If I understand correctly, M/R in 4Lo or 4Hi seeks to dole out engine power in exactly the amount and to exactly the wheel(s) that can handle it. So if you were to stand on the throttle the computer would say, "Thank you very much for the suggestion, Cap'n. We've taken it under advisement, sent some power out to all 4 wheels, found instantly that Numbers 1 and 3 can't take any power at all so we eliminated them; No. 2 can take 23 pounds-feet and No. 4 can take 19 pounds feet without slipping, so that's what we've sent. You might want to back off on the throttle a little because you're just burning gas."
Then, as that little bit of torque gets the truck moving forward slowly and right on the cusp of slipping, your new forward momentum brings with it the ability to take more power and the computer knows that right away and doles out a little more to the wheels that can take it, and then more, always remaining on the edge of traction, until you are up to speed or out of the slop. So you have a very (unnaturally) soft throttle in that mode any time you are in slippery muck; otherwise it's pretty much like Normal mode if you're on hard packed, tractive surfaces.
This is brilliant - and exactly what I was hoping @TrioLRowner + @NoGaBiker . I do have the rear locking diff. And it makes sense now why it was up above 3200/3000 RPM's to get moving.
Kind of surprised how differently this acts from my older LR3/LR4/RRS in mut/ruts mode. But it works and is all a bit less dramatic in doing so that other Rovers.
Oh I forgot one funny thing. In the middle of my mud/snow not really "mud rutting" the Defender popped up a dash message saying "Recommend changing to Auto Terrain Response setting for road conditions". Totally forgot about that. I did it when I stopped. As if it *knew* I was perhaps in the wrong setting.
Yep, the first time my new Defender proctored me in that manner was a real wake up call. I was shocked !! It was then that I began deeply thinking about what it was doing and why. And it was right, of course.
The reason the new Defender's propulsive efforts are not as dramatic as in other rovers is that a torque vectoring e differential is not a limited slip diff. -- nor is it attempting to approximate one (either with a single clutch, or centrifugal force, or mechanical force, or with braking at the wheels).
For a limited slip differential to work, there must exist a difference in rotational speed between the two wheels of the axle. This is not the case for the torque vectoring differential. With its two clutches, it can generate a difference in speed between the wheels beginning at zero rpms on both wheels.
Which wheel is controlled is also delinked from the nature of what either wheel is experiencing -- so it can torque vector into and out of a corner.
This is why ATPC is only effectively possible with a diff. with two separately actuated clutches -- and why TR2 is married to ATPC and the ediff. in the new Defender.
Truly state of the art.
Enjoy !
Last edited by TrioLRowner; 06-06-2022 at 04:22 PM.
All I can add is I normally will have the shifter in manual mode when driving in LO. The reason, is I find that 1st is too low for starts on terrain like you were driving in. I find myself driving in 2nd to get the ball rolling and then shifting it back to manual once we get moving. I also agree with what Trio was saying about using grass/gravel on that type of terrain.
Ymmv, but in those conditions - I would have tried the "Auto" mode if you have it. Let it just figure itself out better than me guessing whether to use Mud or grass/snow.
Ymmv, but in those conditions - I would have tried the "Auto" mode if you have it. Let it just figure itself out better than me guessing whether to use Mud or grass/snow.
Don't forget about the configurable options in TR2
06-06-2022, 11:52 AM
Odd Defender behavior Offroad in 4L/Mud Ruts, Also an air suspension error msg
