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MY12 SDV engine flat spot won't pull selected gear
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Jasonb
 


Member Since: 04 May 2013
Location: Bristol
Posts: 97

United Kingdom 2012 Discovery 4 3.0 SDV6 HSE Auto Aintree GreenDiscovery 4
MY12 SDV engine flat spot won't pull selected gear

Seem to be having an increasing feeling that there's a big flat spot in the engine performance in MY12 SDV 8 sped.

Only had it a few weeks. I first notice it while towing with it hunting a lot between 7th and8th gear. Towed down to Cornwall on Saturday and found that putting gearbox in S mode I could hold the gearbox in 7th and get a calmer journey holding 60-65mph

General Driving 4up around in Cornwall without trailer and gearbox seems to always change up to a gear the engines unable to pull of is in a flat spot. When you try to accelerate a little the engine is flat and won't respond, so you press a bit harder which creates a rushed kick down and jerky progress.

Seems to happen when try to cruise around 70mph. If you try to add a little power its as if it's in too high a gear and won't pull, so you press a little harder which creates a jerky kick down and rapid unintended acceleration.

It's as if there's a flat spot around 1400 rpm right at the engine speed the gearbox is trying to keep the revs at

Feels like there's been a drop off in the available toque at lower rpm

There are no fault codes in the car.

Any thoughts / known issues ?
  
Post #147819124th May 2015 8:35 pm
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Jasonb
 


Member Since: 04 May 2013
Location: Bristol
Posts: 97

United Kingdom 2012 Discovery 4 3.0 SDV6 HSE Auto Aintree GreenDiscovery 4
D4 hesitation and EGR valves

Beginning to think my issue might be down to EGR valves getting sluggish. Getting a lot of hesitation at low speed when rounding corners and at roundabouts.

The gearbox software has been updated but no improvement.

Theres very little on the forum about D4 EGR problems, mine has 70k miles.

Has anyone had EGR issues on a D4 and what were the symptoms ?
  
Post #148918517th Jun 2015 10:29 pm
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Gareth
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Member Since: 07 Dec 2004
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I am not aware of an egr failure on the 3.0 engine. There have been a few turbo related issues, but on the whole its a reliable unit.
  
Post #148919017th Jun 2015 10:59 pm
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Muddy Steve
 


Member Since: 23 Jan 2015
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Post #148921718th Jun 2015 7:11 am
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Robbie
 


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United Kingdom 2013 Discovery 4 3.0 SDV6 HSE Auto Baltic BlueDiscovery 4

Probably best to diagnose the issue first before adding a remap. The 3.0L and 8-speed should pull like a train.

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Post #148922518th Jun 2015 7:31 am
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Gareth
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Member Since: 07 Dec 2004
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Jasonb wrote:
Hi Gareth

Thanks for you reply re my D4 egr question. I see from your profile picture you have a Series 2 ? I'm in the process of a chassis up rebuild of a 1960 S2. Engine built, currently refurbing the axles.

Sounds like from what you say and what I don't read about 3.0 egrs that they're unlikely to be my issue. What sort of turbo issues have there been and what sort of symptoms would I see ?



Thanks Jason


Jason, there are a few threads on here with turbo issues, cracked manifolds, etc. If you use the Search facility, and use the words "Turbo Valve Manifold" in the Technical D4 forum, you will get 3 relevant answers. These are not necessarily your problem, as Robbie says, get the fault codes read for an accurate diagnosis.
  
Post #148925318th Jun 2015 8:25 am
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Jasonb
 


Member Since: 04 May 2013
Location: Bristol
Posts: 97

United Kingdom 2012 Discovery 4 3.0 SDV6 HSE Auto Aintree GreenDiscovery 4

Thanks Robbie, will looking into this.

Generally my 3.0 SDV pulls like train, it's just this annoying hesitation
  
Post #148931218th Jun 2015 11:28 am
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al cope
 


Member Since: 08 Nov 2005
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Is it a hesitation ?, as I was about to post in a similar vein. My 2012 has what I'm calling a "dead" feeling. Its usually if I'm cruising on a light throttle, then engine will suddenly feel like its gone flat - really hard to describe/liken to something else. The revs dont drop, the speed doesnt drop, and as soon as you touch the gas there's no hesitation/kick down as you describe, just this off feeling of the engine dropping the power.

Al
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Post #148968919th Jun 2015 7:05 am
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Jasonb
 


Member Since: 04 May 2013
Location: Bristol
Posts: 97

United Kingdom 2012 Discovery 4 3.0 SDV6 HSE Auto Aintree GreenDiscovery 4

Hi Al,

Your description of the dead feeling is exactly it - The trouble I have through is if I try to then accurate a little the engine won't develop any more power (it's flat), so I then have to push a little harder which generates a kick down and surge forward when all I wanted is a gentle speed adjustment.

The issue is at its worst if cruising at 65-70mph. If I'm doing 80 its not an issue, but I trend to spend most time at 70mph or just below range.

The issue is more pronounced with the caravan on and trying to hold say 60mph +/- 5 mph. I find the gearbox gets into hunting situation with the slightest gradient or speed change because of this dead zone.

I replaced the throttle body as I read a TSB about it sticking but the issue is still there.

I'm thinking it could be sluggish EGR valves. From my understanding of their operation, on light throttle/ speed output the egr's deliver more exhaust gas to keep the emissions down, but they have to close quickly when power is requested to deliver the power.

I wouldn't mind the dead feeling if the engine would respond when requested.

If I hold the car in gear using command shift to avoid the kick down the engine will respond well but I feel there's a slight delay/hesitation before the power builds.

Other than that power output is fantastic and a brilliant tow car compared to my D3
  
Post #148969719th Jun 2015 7:54 am
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Kilovolt
 


Member Since: 29 Jun 2015
Location: South Derbyshire
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United Kingdom 2013 Discovery 4 3.0 SDV6 Commercial XS Auto Baltic BlueDiscovery 4

Might be a red herring this (for you) but LR attended my 2013 SDV6 a few weeks ago. Real nice chap.

Same symptoms you are describing plagued me. Jumpy when cruising. But keen to go if you booted it. Seemed to be gear hunting all the time.

Nice man said easy. Motorised air intake flap in the front grill.

Sticks/binds and throttles the engines air consumption. ECU gets upset at varying air flow and therefore the gear box hunts a lot (uneven torque delivery).

He took it apart. Lots of WD40. Drunk some tea. Tested it with his laptop. Been fine ever since.

I have 55k miles on the clock. He said perfect mileage for that failure. He had to fix his own D4 a few months ago for exactly the same symptoms and similar mileage.

Been fine ever since. Might be worth checking the same for you?

Not an on obvious one to deduce but a simple check for starters.

Cheers.
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Post #150774427th Jul 2015 7:55 pm
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Jasonb
 


Member Since: 04 May 2013
Location: Bristol
Posts: 97

United Kingdom 2012 Discovery 4 3.0 SDV6 HSE Auto Aintree GreenDiscovery 4

Hi Kilovolt,

Thanks for the info

Are you referring to the Throttle body on top of the engine or the Turbo shut-off valve which is behind the front grille low down on the drivers side (right) just behind the radiator pack ?

I've replaced the throttle body with the revised part that doesn't stick. I'd be surprised if an LR engineer would go for a WD40 fix when an revised part is known to fix so I'm hoping you might be referring to the Turbo Shut-off.

The main problem I'm left with is hesitation from a standing or rolling start. Seems the engine takes a second to start delivering torque and until it does the gearbox doesn't hook up - then it takes off.

Cheers
  
Post #150774727th Jul 2015 8:09 pm
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Kilovolt
 


Member Since: 29 Jun 2015
Location: South Derbyshire
Posts: 1067

United Kingdom 2013 Discovery 4 3.0 SDV6 Commercial XS Auto Baltic BlueDiscovery 4

Good morning,

Did not pay to much attention at the time to be honest (let the man do his job and not hawk eye over his shoulder) but it was front grille off and a motorised louvre he was messing with. Not the throttle body on top of the engine.

And to be honest, if WD40 gets it sorted in 30 minutes and I dont have to suffer a morning at the stealers wrestling with their crap wifi or worse still, have to spend all day driving round in a Freelander that has not had the insides cleaned for lord knows how long, then that's great by me Smile

Good luck all the same.
 "Track day running - Don't put your foot back on the accelerator until your absolutely sure you don't have to take it off again"

Current Ride: D4 XS Commercial Baltic Blue SDV6 fully loaded with heated everything Smile
Track Days: BMW E36 M3 Evolution MY 1996 (3.2 Litre 377 BHP sat in 1,250 Kgs of car, with a pro safety cage and some serious braking power) Smile 
 
Post #150790228th Jul 2015 6:22 am
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Jasonb
 


Member Since: 04 May 2013
Location: Bristol
Posts: 97

United Kingdom 2012 Discovery 4 3.0 SDV6 HSE Auto Aintree GreenDiscovery 4
Turbo shut off / Change over valve

Some times when I shut the car down among the various actuator reset noises I here a Donk,Donk noise from the area where the Turbo Change over valve is.

Sounds like it's doing an open/shut reset but it doesn't do it every time I shut down, perhaps 1 in 5 times.

Can make my mind up what should be normal. Should it make the reset noise on each shutdown or not at all

I suspect it might be sticking
  
Post #15125317th Aug 2015 7:47 am
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