Climbing dunes in a D4 - engine cutting revs

[TuffRR]

Took the D4 for its first sand trip on the weekend. So far this car has been a bit love/hate off road. Sometimes it really surprises in how capable it is, and others i'm left scratching my head why it won't do what i want.

Had one long steep dune with soft sand. Car was in sand mode, dsc disabled and in high range command shift. Was climbing the dune, making good progress sitting on about 3800 rpm, when all of a sudden about 10 metres from the top power was cut and revs fell to 1000rpm. As soon as this happened, forward momentum ceased and i had no hope of making it further. Backed up, tried again and similar thing happened but much earlier on. At this stage, was pretty frustrated so gave up and found another way.

Was this cutting of power DSC cutting in? I know it doesn't completely disable even when switched off, but this was :censored: frustrating. I think I've experienced the same thing on slippery climbs in the high country too.

Starting to think that terrain response is more trouble than its worth. Sometimes finding the right settings is like trying to get the planets to align.

[LRD414]

Such an aggressive cutting of engine revs doesn't seem like any instances of DSC application I've experienced or heard of.
But others may know more.

Did you notice a light something like this photo flashing up on the dash?
https://www.aulro.com/afvb/images/imported/2016/06/611.jpg
This is the DSC actually doing something.

Was there any holes in the sand causing side-to-side rocking or was it pretty much straight up?
Is it at all possible you had switched between TR modes or turned engine off and then forgotten to turn off DSC again?
(I'm not being smart, it's just something that's happened to me).

Also, 3800 revs is pretty high and you mention being in high range.
Did this go on for long?
Could it have been a thermal issue, perhaps transmission?
Any other lights/symbols on the dash?

For this type of work I always use low range, more sympathetic to the drive train.

Cheers,
Scott

[apom]

Yep, i have experienced something similar on Fraser island. Not as drastic but there was a definite drop in power. Only seems to happen in high range and not low range in my experience. I thought it was to do with the trailer attached at the time but couldnt pin point it.

I certainly wasn't that high in the rev range but the throttle definitely didn't respond to input when asked and stopped it prematurely. Low range in sand is more reliable in my experience on the trips thus far as Scott suggests

[TuffRR]

Did you notice a light something like this photo flashing up on the dash?
https://www.aulro.com/afvb/images/imported/2016/06/611.jpg
This is the DSC actually doing something.

Not that i recall - and i was keeping an eye on the tacho.


Was there any holes in the sand causing side-to-side rocking or was it pretty much straight up?
Is it at all possible you had switched between TR modes or turned engine off and then forgotten to turn off DSC again?
(I'm not being smart, it's just something that's happened to me).
No holes, sand was pretty soft and deep so it was relatively smooth. Climb was straight up. All was in the right mode as I'd only selected it all at the bottom of the climb.


Also, 3800 revs is pretty high and you mention being in high range.
Did this go on for long?
Could it have been a thermal issue, perhaps transmission?
Any other lights/symbols on the dash?

Don't think it was a thermal issue as drive to the dune was easy. The car wasn't struggling for power or slipping through the torque converter (hence 3800rpm) so not thinking a thermal issue. No other lights on dash either.

With more time i would of played longer to find out what works best but unfortunately it was getting late in the day and we still hadn't found camp.

[MrLandy]

There's no substitute for low range.

[BobD]

This is what I have found.


Always use low range in sand unless touring for long distances.


For sand hills, sand mode low range 3 or 4 is best, rather than auto mode. For more normal sand driving low range auto is good. If you put your foot down too much to maintain a lower gear in auto mode the car will cut power to try to maintain traction, or something like that known only to LR, even with DSC off. If you use a set gear you can keep the accelerator around mid range or less and still get heaps of power without the car deciding to cut power.


I recently did the hard track up Big Red and found the D4 flew over the top (backing off a lot at the top to slow it down) in either 3 or 4 low range with no run up at the bottom. I started in third and then changed to fourth which went the best on Big Red. No one else on the day I was there (four weeks ago) could get close to the top, even with long run ups. The closest was a Prado who copied my line after watching me do it several times with no worries. He got to about 10m from the top. All this was in my fully loaded D4 which weighs 2740 kg empty.


I will try to post a video some time if can work out how!

[TuffRR]

There's no substitute for low range.

There kind of is though....

Low range 3rd final drive ratio 15.77
Low range 4th final drive ratio 11.85

High range 1st final drive ratio 14.76

Given all the elec-trickery things that happen behind the scenes on a D4, i wonder if there is a difference in TR settings between high and low range in sand mode?

[BobD]

There kind of is though....

Low range 3rd final drive ratio 15.77
Low range 4th final drive ratio 11.85

High range 1st final drive ratio 14.76

Given all the elec-trickery things that happen behind the scenes on a D4, i wonder if there is a difference in TR settings between high and low range in sand mode?


Low range activates all the off road trickery and optimization in the D4. It makes a big difference. It is not just a simple ratio change.


I was once trying to drive fast along a beach at Esperance following my reckless son in law in his 80. He was on the wet part of the beach but I didn't want salt on the car so I was in softer sand higher up the beach. To keep up I used high range and after about 10 minutes of fanging the car along the beach it ground to a complete halt. Not sure why but I put it in low range and went my own speed with no problems after that.

[TuffRR]

Low range activates all the off road trickery and optimization in the D4. It makes a big difference. It is not just a simple ratio change.


I'd agree for some modes, ie rock crawl, but did not think it made a difference in others ie sand and snow/gravel. Surely Land Rover dont expect you to drive gravel and grass in low range for the optimisations to work?

[rocmic]

I'd agree for some modes, ie rock crawl, but did not think it made a difference in others ie sand and snow/gravel. Surely Land Rover dont expect you to drive gravel and grass in low range for the optimisations to work?

No not gravel and grass but there is more that goes on under the hood than you, or I, know. Maybe Gordon or Tombie can chime in at some stage. I for one would like their opinions.
Cheers
Mike

[LandyAndy]

How hard were you pressing the loud pedal???? 100%????
In Gordons course he says the DSC will still work when under full throttle/load.If you havent got the handbook,order a copy from his website.Some very good info there,its basically the course notes.
Im with the others,low range,unless its hardpacked sand and you are travelling a long way.
Andrew

[LRD414]

I recently did the hard track up Big Red and found the D4 flew over the top (backing off a lot at the top to slow it down) in either 3 or 4 low range with no run up at the bottom .... I will try to post a video some time if can work out how!
Please do Bob, I'd like to see it. Will be out there late July.

Scott

[TuffRR]

How hard were you pressing the loud pedal???? 100%????
In Gordons course he says the DSC will still work when under full throttle/load.If you havent got the handbook,order a copy from his website.Some very good info there,its basically the course notes.
Im with the others,low range,unless its hardpacked sand and you are travelling a long way.
Andrew

No, hard pedal was not 100%.

Gordon's book suggests that revs should be maintained around 3500rpm to keep momentum. So was pretty close to that.

So 2 key questions for clarity if Gordon or others more informed can answer...
1) would revs dropping to 1k be a sign of DSC kicking in even when DSC is switched off; and
2) does sand mode operate differently between high and low range?

[BobD]

How were you keeping the revs at 3500? If you were in drive in high range you would have to have hard accelerator, which will activate traction control and reduce power. Even if you put it in first high range and hold it there manually rather than low range fourth you will have much less accellerator pedal. As soon as you use too much right foot in the D4 on sand it cuts power, whether we like it or not.


Read the FAQ at the top of the forum and Gordon's book to find out how low range changes lots of settings in the car to make it work better off road. Others have posted previously how there D4's would not go up long sand hills like their old Patrols and Toyotas but putting it in low range fixed it.


I was experimenting in sand dunes at Albany over Christmas after I could not get up a soft sand hill that my son's D1 TDI 300 auto just walked over, even in low range. Like you, it would power up and suddenly lose power as I increased throttle openings to maintain speed in auto mode. I thought about what I would do in my Patrol and realised I woud be in third low range in my 6.5 Chev powered vehicle. I tried that in the D4 and it just walked over as easily as any old Toyota, D1 or Nissan. I've since done it on many sand hills in WA and also Big Red with the same results. You cannot have lots of loud pedal on sand hills.

[LandyAndy]

Great info Bob.
Thinking about it,our last fishing outing at Horrocks,I made a track for myself at our fishing spot by driving back and forward so I could get out later.Aaron didnt even get close to where I was,I rekon he was in hi-range.He ended up spitting the dummy and walking to where we were fishing:):):):).
I hope these GOE wheels and Cooper AT3's peform better than the OEM tyres.
Andrew

[BobD]

Andy,


The few times I have been stuck in very soft sand I've had my tyre pressures too high. Each time I just lowered the tyre pressure to around 18, put it in Rock Crawl mode and drove straight out. I always carry Max Trax but I can't remember needing them on the D4. Used them a couple of times for the Patrol. The 285 x 18 inch tyres make sand better but I didn't have a problem with the OEM tyres, even in very soft sand at Muchea at road pressures, where the Patrol would struggle on 33's at 18 psi.

[LandyAndy]

On the day we were using 15psi and strugling,it was very soft and deep sand.Aaron did have to deploy the max tracks once that weekend,they work really well with the D4s electronics.
Andrew

[Ben_Vapid]

I had a very similar problem in the high country over the weekend. I'd hit a really steep rough section in high range and the car would suddenly pause, almost like it's gearing down. It's always at the worst time when you needed momentum to crest a hill or something. Low range never behaves like that.

It seems special programs + high range doesn't like low speed steep inclines.

[Russrobe]

On the day we were using 15psi and strugling,it was very soft and deep sand.Aaron did have to deploy the max tracks once that weekend,they work really well with the D4s electronics.
Andrew
Did you use one pair of Maxtrax Andy? I was hoping I'd get away with just the one pair I bought if needed.... Fits nicely tied up against the back of the cargo barrier. .. Seems most people use 2 pairs though?

[BobD]

You only need one pair for a D4 in most situations. In fact, the traction control is so good you can place them on diagonal corners as recommended by Gordon. I usually use the front wheels so you get the second boost when the rear wheels run over them. When towing you may need a second or third set but for the car by itself one pair is usually plenty.

[gghaggis]

The auto re-latching of the DSC is very hard to avoid in high range. As it should be. Power variation with throttle position is very different. Hence why you should not use high range for long steep dune climbs.

Cheers

Gordon

[LandyAndy]

Did you use one pair of Maxtrax Andy? I was hoping I'd get away with just the one pair I bought if needed.... Fits nicely tied up against the back of the cargo barrier. .. Seems most people use 2 pairs though?

Just the 1 pair and it drove out like it hadnt even been stuck.
https://www.aulro.com/afvb/images/imported/2016/06/489.jpg (http://s113.photobucket.com/user/LandyAndy_2006/media/20160107_160853_zpspcmjypeq.jpg.html)
Andrew

[Aaron40]

you weren't... I was... new I shouldn't have stopped there.... wish I had my camera when you were spinning away...:mad:


Just the 1 pair and it drove out like it hadnt even been stuck.
https://www.aulro.com/afvb/images/imported/2016/06/489.jpg (http://s113.photobucket.com/user/LandyAndy_2006/media/20160107_160853_zpspcmjypeq.jpg.html)
Andrew

[Russrobe]

Bahahaha nobody wants to get snapped bogged.

Driving yourself out voids all embarrassment though!

[Celtoid]

I've had a couple of similar issues, the most noteworthy on Fraser Is. It had been raining and I was running 285/18s on GOE wheels at 16 - 18 psi. I basically went back to high range and I think I 'switched' everything off. DSC was definitely off though.


I was going along on a very slight incline and came to one of those erosion control berms so I popped the throttle to ride over it. Absolutely nothing happened ..... not a slow build and then whoosh like some OPs report at roundabouts .... absolutely no change in throttle. Even when pressing welly to the floor, there was no noticeable increase in revs.


It's happened a few times now but never in Low-Range.


Don't know what's behind it.

[scarry]

I have noticed it as well,as an example,mine did it on occasions during a Simpson desert crossing.

In high range on the flat,going slow,say around 45k/hr,then going slightly uphill,then back off as you hit a set of ruts at the base,or about a quarter of the way up a dune,over the ruts,foot down,nothing happens,no go at all.

I have shot up dunes,at speed on beaches,etc and never noticed it happen.Only noticed it at slower speeds,say under 50k's/hr.

In low range it never seems to happen.

As Celtoid has said,what is the reasoning as to why they do this?The vehicle is obviously designed this way for what ever reason.

[Mungus]

I have no experience with this yet, so it is good reading about this stuff. Based on what Gordon said in his previous post, I'm guessing in high range and therefore presuming at higher speeds, Landrover won't let the driver have control and therefore re-instate DSC automatically without any indication. So it sounds like DSC is never actually able to be completely disabled as such, just selected off until the vehicle decides it needs it again, apparently more so in high range.

[LandyAndy]

I have no experience with this yet, so it is good reading about this stuff. Based on what Gordon said in his previous post, I'm guessing in high range and therefore presuming at higher speeds, Landrover won't let the driver have control and therefore re-instate DSC automatically without any indication. So it sounds like DSC is never actually able to be completely disabled as such, just selected off until the vehicle decides it needs it again, apparently more so in high range.

Basically thats Gordons words in his theory course.With the 8 speed you get a pretty good spread of speed ranges in low range,and that oh wow instant power my modified D2 could never match.
Andrew