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| Dora Member Since: 12 May 2015 Location: South East Posts: 170  
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Just seen a similar long running thread on here and I think it could well be a fuel related problem.
I have always used Shell in my diesel vehicles as I was told it was a good product used by racing teams. I therefore automatically used it in this vehicle and last fill up used their premium diesel as a bit of a treat.. It's been much worse since then, maybe i'll try another premium brand like BP and see waht happens..... I'll keep you posted  |
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11th Jun 2015 7:40pm |
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| Lorryman100 Member Since: 01 Oct 2010 Location: Here Posts: 2686 |
As I am sure we all know a Diesel engine is generally not capable of pinking because prior to injection of the fuel it is only air that is being compressed, as there is no fuel mixed in, there is nothing to pre ignite (A petrol engine can pink due to pre ignition of the air/fuel mixture as a hot spot ignites the fuel prior to BTDC, eg: a faulty or wrong type of spark plug fitted). On the Puma fuel is delivered into the cylinder progressively in three stages and the knock you hear is due to the heavy compression of the air in the cylinder BTDC as the fuel ignites. But injection is not instantaneous, injection lag—the time required to build injection pressure and get it to the nozzle and “pop” it open, delays things. Once fuel is injected, ignition lag also occurs. Injector design and spray pattern, compression temperature, fuel cetane rating, and more influence ignition lag.
The “lag” during the compression stroke tends to cause diesel fuel to ignite spontaneously, thus creating the familiar diesel knock or “clatter” sound; upon ignition, cylinder pressure suddenly rises and “rings” the cylinder. This sound is noticeably louder on a cold engine as the EMS fuelling protocol allows for more fuel into the burn firstly to help overcome the cold mass of the engine block and get the engine started and then to keep it running as it warms up. The EMS knows the temperature of the engine via the CHT sensor, the air temp coming into the engine first at the MAF sensor and then before it goes into the cylinder from the MAP/T sensor. As the engine warms less fuel is used and the clatter subsides. When the engine is warm and running at say 2000 rpm the amount of fuel required to maintain these revs depends on engine load and temp. Then if you depress the accelerator pedal, a higher load is put on the engine and more fuel is needed to accommodate this load which results in injector lag and cylinder pressure suddenly rising and rings the cylinder which sounds like Knock. You can reduce the Knock by using a higher cetane fuel (I use BP Ultimate every tank) and you can raise the cetane number higher again by adding an additive to the fuel, I use Millers Oils Diesel Power Ecomax Fuel Additive Treatment every tank resulting in a quieter engine but you will never get rid of the clatter, knock or perceived pinking as that is the result of the combustion process in a diesel engine. HTH |
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11th Jun 2015 8:55pm |
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| Dora Member Since: 12 May 2015 Location: South East Posts: 170
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Thanks Lorryman, nice explanation.
I think I will try the BP option and see if that makes a difference, then the additive, glad it's fairly normal though and not going to be expensive! |
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11th Jun 2015 9:09pm |
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| frenzy Member Since: 26 Sep 2015 Location: queensland Posts: 6  
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Thanks Lorry, this makes sense, but if this was the case wouldn't any diesel engine have the same "issue" I have driven Hilux and have not heard this rattle sound at all. I understand a little bit of it is normal and acceptable but when all your passengers isay " what's that noise man
 ?" that to me means it's a bit unusual.
I have had the s issue with my 2007 110 puma since I bought it with 70.000 km My Land Rover mechanic said " this is not a normal sound, have not heard this loud before". He replaced the ECU and remapped it but the rattle remained ( so we put back the old ECU). Another non LR mechanic said it is early detonation possibly due to a wrong ECU setting and suggested to check if there are any software updates that would address the problem. I will try with a premium diesel and some additives to see if it makes a difference. cheers |
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5th Oct 2015 2:58am |
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| Lorryman100 Member Since: 01 Oct 2010 Location: Here Posts: 2686 |
Compared to other vehicles the Defender is quite unique in having no sound insulation which makes every noise sound worse than it would be within a nice sealed insulated driving cab.
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5th Oct 2015 1:46pm |
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| Rugerrog Member Since: 16 Jan 2015 Location: Derbyshire Posts: 12  
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Well after starting this off me and my pinking 90 parted company 1/2 way down the Motorway and that certainly stopped the pinking !!! so now I have a late 14 plate 110 station wagon 16,000 mile and pinking !!!
 not as noticeable as the 90 but to the trained ear its there so Im not worried about it as it seems to be just another land rover characteristic feature Current Landy is a 110 2.2 Puma bit different from my first one a Series 1
with a straight 6 petrol engine  last one was a 2.2 puma 90 but the M4 crash barrier took care of that !!!! |
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28th Oct 2015 8:45pm |
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| Caterham Member Since: 06 Nov 2008 Location: Birmingham Posts: 6276 
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Can I suggest a strong dose of redex and se I it makes a blind bit of difference?
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28th Oct 2015 9:25pm |
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