What is the difference between....

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SamF81

SamF81

Member
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31
Location
Sheffield
What is the difference between the fuel rail pressure sensor and fuel pressure regulator???

I have had my car in the garage (that supposedly knew landys inside out) as it had loss of power, it was kangarooing and rough idle. They replaced the fuel rail sensor with one that looks like the LR009732 but now it is still kangarooing, the power is back but its got black smoke and an almighty rattle when you put foot down.

I've looked in haynes and tried googling both to see what the difference is and know that the sensor obviously goes in the rail and the regulator near the injection pump but cant find any difference in the pictures that come up!

Mine is a 53 plate facelift TD4. I have replaced the cam sensor, fitted an EGR blank, a MAP (boost pressure) sensor and now this fuel sensor. Unplugging the MAF before the fuel sensor replaced made no difference to how it was running. :(

I'm wondering injectors but a different local garage are saying they'll need to be sent for testing at £30 each.

Also if it is run without the fuel sensor plugged in what will happen?
 
SamF81 said:
What is the difference between the fuel rail pressure sensor and fuel pressure regulator???

I have had my car in the garage (that supposedly knew landys inside out) as it had loss of power, it was kangarooing and rough idle. They replaced the fuel rail sensor with one that looks like the LR009732 but now it is still kangarooing, the power is back but its got black smoke and an almighty rattle when you put foot down.

I've looked in haynes and tried googling both to see what the difference is and know that the sensor obviously goes in the rail and the regulator near the injection pump but cant find any difference in the pictures that come up!

Mine is a 53 plate facelift TD4. I have replaced the cam sensor, fitted an EGR blank, a MAP (boost pressure) sensor and now this fuel sensor. Unplugging the MAF before the fuel sensor replaced made no difference to how it was running. :(

I'm wondering injectors but a different local garage are saying they'll need to be sent for testing at £30 each.

Also if it is run without the fuel sensor plugged in what will happen?
Click to expand...

The rail pressure sensor is just that. It measures the fuel rail pressure, sending the information to the ECU. The pressure regulator is in the HPFP and is what the ECU controls the fuel rail pressure with.

£30 each for an injector test is a good price, £50 is more normal.

Unplugging the pressure sensor can cause odd running faults, much like you have.
Have you plugged the MAF back in?
 
Yes MAF is plugged back in, it didn't make a difference to how it was running when it was unplugged so plugged it back in and figured it wasn't that. When I got it I ordered air filter, crankcase breather filter and turbo breather filter but it turned out it already had the modified crankcase breather.

Since I cant find a picture of a fuel pressure regulator I'm presuming they don't look alike? When I searched for fuel rail pressure sensor I was getting results that said both like this: http://www.ebay.co.uk/itm/freelande...il-pressure-sensor-m47-LR009732-/261264409276 which just confused me (easily done), but that is what the replaced sensor now looks like. Could they have put the wrong sensor in? I know the 2.2l is different and looks different.

It was having a problem with rough idle and after a trip to a landy garage 20 miles away and codes wiped and fuel sensor plugged cleaned it ran sweet for a few weeks at least. When it cuts out it doesn't want to start again, if you unplug the fuel sensor and plug it back in it fires up then. The fuel rail sensor replacement does seem to have left it idling better but now as i say there is a horrible noise when you put your foot down and usually a blast of black smoke to go with it.
 
SamF81 said:
Yes MAF is plugged back in, it didn't make a difference to how it was running when it was unplugged so plugged it back in and figured it wasn't that. When I got it I ordered air filter, crankcase breather filter and turbo breather filter but it turned out it already had the modified crankcase breather.

Since I cant find a picture of a fuel pressure regulator I'm presuming they don't look alike? When I searched for fuel rail pressure sensor I was getting results that said both like this: http://www.ebay.co.uk/itm/freelande...il-pressure-sensor-m47-LR009732-/261264409276 which just confused me (easily done), but that is what the replaced sensor now looks like. Could they have put the wrong sensor in? I know the 2.2l is different and looks different.

It was having a problem with rough idle and after a trip to a landy garage 20 miles away and codes wiped and fuel sensor plugged cleaned it ran sweet for a few weeks at least. When it cuts out it doesn't want to start again, if you unplug the fuel sensor and plug it back in it fires up then. The fuel rail sensor replacement does seem to have left it idling better but now as i say there is a horrible noise when you put your foot down and usually a blast of black smoke to go with it.
Click to expand...

Was the replacement harness fitted at the same time as the new sensor? There is a kit to replace both sensor and a new sensor harness. The original harness suffered corrosion and cracking of the wires.
I suspect that this is where your problem lies ;)
 
I believe only the sensor was changed. Would the harness not being replaced cause the black smoke and rattle tho?
 
SamF81 said:
I believe only the sensor was changed. Would the harness not being replaced cause the black smoke and rattle tho?
Click to expand...
From my understanding of the ECU and it's interpretation of the sensor reading. If the voltage from the sensor is low, the ECU will think the fuel pressure is lower than it actually is. This means that it increases pressure by opening the pressure regulator longer, or opens the injectors slightly longer. Both of these things would increase black smoke production. However that is just a theory of mine, based on symptoms and the fact that LR released a harness kit as a fix.
 
I wonder if these harness kits can be made up, by your self using the original plug's I feel a project and how to coming on
 
I had that while I was in Ireland and we struggled back to the cottage and when we got back we found it was a turbo hose had gone in a big way ,as you said loss of power and engine rattle .if I had just stopped when it happened then I could have fixed it as some how the small hose had just blown off , so check your hoses .
 
GrumpyGel said:
Is the idea of the upgrade that it has upgraded connectors? I don't suppose the wires are.
Click to expand...

Arhhh right I thought the wiring broke down over time due to outer casing going brittle and the inner wiring failing ? what happens to the connectors then for them to fail ?
 
Arctic2 said:
Arhhh right I thought the wiring broke down over time due to outer casing going brittle and the inner wiring failing ? what happens to the connectors then for them to fail ?
Click to expand...

The connector can corrode, which then tracks moisture up the cables, causing them to fail too.
The replacement harness has a different seal, which should stop this from happening again.
 
Nodge68 said:
The connector can corrode, which then tracks moisture up the cables, causing them to fail too.
The replacement harness has a different seal, which should stop this from happening again.
Click to expand...

Hi Nodge.
Thank you for the reasoning behind the change, mainly the reason I asked was/is I have a least three spare harness I the shed
 

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Arctic2 said:
Hi Nodge.
Thank you for the reasoning behind the change, mainly the reason I asked was/is I have a least three spare harness I the shed
Click to expand...
The top picture is of two injector harnesses.

Bottom is of a R75 sensor harness, I think.
 
Nodge yes you are right, wrong box but I have three full looms in various boxes, in one for m of state or another, I really must sort them out
 
I have eventually got the wiring loom from LR so I can take it up to my local garage tomorrow for it fitting. Does anybody know where I can download fitting instructions?
 
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