Member Since: 06 Mar 2017
Location: Lost
Posts: 4969
So there's not enough pressure at the rail it seems. Either the HP side is faulty or possibly low pressure side is intermittently faulty or the pipes are incorrectly connected.
Clear the codes then remove the fuse for the LPFP, the car should drive fine with the pump disconnected so long as you are light on the accelerator. If it fails this test have a look at the codes and post them here, but my suspicion is that this is a high pressure side fault.yµ (idµ - eAµ) ψ=mψ
9th Sep 2024 7:25 pm
James M
Member Since: 19 Dec 2023
Location: Scotland
Posts: 19
Yeah rail pressure seems to be a constant problem when the car is first started it’s about 28,000 kpa but once it warms up it drops down to 22,000 kpa and is very fluctuating going up and down like it’s surging / struggling to suck fuel.
The low pressure side has had two new intank pumps , new non-return valve/ tank cover , and lots of filters , and all pipes look fine
So is this test supposed to show that if the hpfp is fine then the car should still run ?
What dose it mean if it won’t start or stay running ?
Yeah it dose just keep looking like it’s the hpfp but what are the chances of getting two new pumps that are both faulty, one after another and then just take the gamble that third times a charm ?
9th Sep 2024 7:52 pm
James M
Member Since: 19 Dec 2023
Location: Scotland
Posts: 19
Ummmm if the fuel pipes just befre before the high pressure fuel pump / feed and return where the wrong way around would the car still run and drive relatively fine but always be struggling for fuel , cause I do remember seeing personally that both metal pipes seem to pump fuel when the ignition is on ?
9th Sep 2024 8:38 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4969
I might be something small but your mechanic is only going to get to the bottom of it by studying carefully what is happening in "live values" and understanding the data.
The oil temp switch in the sump plays an important role here, so it should be monitored closely to eliminate any erroneous signals or switch failure.
It may be something simple, and especially so if you have replaced the major components / pumps and other bits. Did he do a "reset" for the LPFP when it was fitted? Doing so will request the PCM to reset it's adaptations for the LPFP pump and might improve things. Another area that can cause issues is the electrical plugs on the FRPS/HPFP, or even the diesel EMS fuses in the BJB as sometimes they are tarnished or not making full contact with the pins.
Have a look at the screen shot below and you get some idea of what the live values for the fuel system sensors should be doing at idle speed on a healthy engine. These were taken at an idle speed of around 725 rpm, so a lower rpm will bring down the fuel pressure value to around 23.0 kPa.
It's normal for it to fluctuate slightly, eg 22.5kPa to 23.0 kPa or a bit beyond, but not wildly eg 22.5 kPa to 26.0kPa when idling.
Click image to enlarge
The screenshot shows the fuel pressure at the rail, the HPFP volume & pressure control valves operating values, mass air flow, manifold pressure, battery voltage and turbo boost values all taken at 725rpm.
Throwing parts at the problem hoping you hit the "bulls eye" is never a good idea as I'm sure you know by now. Working through the issue methodically, and understanding the data until you start to see something in diagnostics that doesn't look right is really the only way forward. Sometimes you can get lucky but rarely with these complicated fuel systems.
The LPFP fuse removal test is only useful for confirming the complete system is operating correctly, but with it removed it can sometimes point the direction of the fault depending on the codes presented. If you could provide live data from the engine and post it here it would help working through the problem, if that's an option for you.yµ (idµ - eAµ) ψ=mψ
10th Sep 2024 2:38 pm
James M
Member Since: 19 Dec 2023
Location: Scotland
Posts: 19
Hi thanks so much for your help so far !
Well I do have quite a few different graphs / live values that I have taken over the years this it’s had this fault
Click image to enlarge
This is was taken just siting idling
Click image to enlarge
This is a 0-60 graph you could call it but of course the car doesn’t make it to 60 with out going ping
It also shows all the pressures and values positions just before the car gives up and gos in limp mode
Yeah the oil temperature sensor was replaced a few years ago cause it was giving fault codes but seems to be fine now but I can get then to double check
Yeah the lift pump reset has been done a few times
They have tested the wiring back to the fuel box so I’d guess he’s looked at the fuse / had to take it out to test the circuit
Oh I know they just keep throwing money / parts at it to basically save time I’d say and then when you try and say why did you get it wrong again it’s all “ process of elimination “ and trying to find what the fault isn't at this stage , lucky there is currently an abandoned D3 in there car park that they are now taking bits of to try on mine just to “ eliminate “ stuff
10th Sep 2024 6:17 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4969
From the graph you provided it's clear that the high pressure rises steadily until you hit around 140kPa, and judging by the other values it seems you were giving her a good hiding too!
These are from an EU4 engine but they have identical operating parameters.
This first one shows some live values on a relatively cold engine.
Click image to enlarge
This one shows the differences at full operating temperature.
Click image to enlarge
Comparing these with your own above there is nothing that jumps out, but it would be a good idea to watch your battery output alongside the fuel values. Forget about torque as it's not relevant for this diagnosis, just focus on the fuel pump data, battery, oil temp, etc. yµ (idµ - eAµ) ψ=mψ
10th Sep 2024 8:35 pm
James M
Member Since: 19 Dec 2023
Location: Scotland
Posts: 19
Hey , thanks for your thoughts
Hahah yeah when you hit her that hard you’ll only get about 3-4 seconds before ping
But sometimes if you drive very carefully you could do hundred miles with out fault next day you’ll only get ten miles before ping for no reason realy
Yeah I see what you mean I was a bit focused on that it had to be 27,000-28,000 kpa to be normal but like you say at idle as long as it’s above 20,000 then it’s still fine guess it’s all about how quickly it can pick up the pressure when you need it.
Oh well I guess that’s good in a way there definitely nothing obvious sticking out that the dealer should of noticed quickly , strange how everything looks fine but at the same time the fault is there the hole time.
Thanks again for your help I will definitely pass your advice over to my master technician tomorrow
And I’ll defo keep you posted if we make any progress, or the cure if there is one
10th Sep 2024 9:44 pm
Farmer Chalk
Member Since: 07 Mar 2013
Location: Independent Republic of Kentishshire.
Posts: 4190
Had a very very similar issue to yourself and reported on another similar threads..
Mine has appeared to have been cured by a replacement genuine JLR fuel rail with the new fuel rail pressure sensor attached… I say appeared purely as I’ve only had it back a couple of weeks but even so I haven’t been able to provoke the car into limp home mode since…
10th Sep 2024 10:15 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4969
The FRPS might well be an issue here as it's not available separately from LR without buying the complete rail. So it seems only aftermarket sensors are available and I'm not a fan of them. I have tested aftermarket rail sensors on a perfectly working D3's just to see what the result would be. They worked, and there were no faults but the power was down considerably.
When I replaced the old LR sensor and power was restored, so as Farmer Chalk suggests this is worth perusing further especially as the fault code you are being presented with now is P0087!!
This applies to aftermarket HPF pumps as well, but unfortunately it seems new original Siemens/VDO pumps are no longer available for the D3. Only reman, but I'm happy to be corrected and even happier if someone has a source of new pumps.yµ (idµ - eAµ) ψ=mψ
11th Sep 2024 12:31 am
James M
Member Since: 19 Dec 2023
Location: Scotland
Posts: 19
Hey
so thing just get better and then worse at the same time
So spoke to the workshop manager today so on Tuesday they changed the fuel rail pressure sensor after taking one of another persons car just to make sure , then when out for a test drive and it drove great apparently he was doing over 85 mph up a long stretch of hill motorway normally when they take it on the motorway they can’t get from the 50 zone up to the 70 zone without it pinging.
So he then took it out again Wednesday and when he was flooring it up the slip road it just cut out on him and he couldn’t get it to restart , it has never ever cut out like that before to me or them , so they had to get it recovered back on a brake down.
They are hoping that the fault has finally failed / showing it’s face stoping the car from running now and it should be easy for them on Monday to find what’s been wrong it the hole time
But all I keep thinking it that something else has now failed and the engine could be dead , like timing belt or cam chains has snapped , or something stupid they ran out of fuel
Hoping it’s good news in a way but also preparing for the worst !
Thanks for your advice about the pressure sensor it was already changed once for a cheap one but made no difference so put the old one back in , but looks like the dealer wanted to try again.
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I will definitely pass your advice over to my master technician tomorrow
