Undiagnosable Freelander problem! Help!!

Hi Everyone,

This is my first post so sorry if I have done something wrong.

I have a 2006 freelander sport 2.0d auto.

Normally the car is fine it has done 121,000 miles and regularly serviced.

Recently the power in the car has been lacking massively, as I drive down the road the engine can splutter and sometimes stall. The engine can take upto a minute to start with or without throttle pedal depressions, and there is abit of black smoke from exhaust along with a hunting idle.

So far I have done the following:
Installed a blanked EGR valve and cleaned surrounding components- very little difference made
Cleaned the crankcase breather filter - no difference.
Replaced fuel filter - no difference
cleaned maf sensor - no difference
Replaced fuel rail pressure sensor - no difference.

When I had diagnostics on the car the only fault code found was fuel rail pressure sensor error - fuel rail pressure sensor voltage low.

I can hear the fuel pump next to the fuel filter working and I'm confident it is not that however if feels like a fuel delivery problem.

Does anyone know of any common fault or think of something I have missed?

Finally I have one more question, with the maf sensor disconnected car runs exactly the same. However I thought this was weird so I compared to my 225+bhp golf gttdi and this is the same. It may be a stupid question but how come the maf/map sensors make no difference? are the engines ECU's compensating and running the engine and if so if an engine runs the same without them then why do we need them?

Thanks for you comments in advance!

You need to monitor the live data and look at low fuel pressure (min 360kpa) and high pressure

Also need to get injectors tested - leak back test is a test you could do yourself with some basic tools

MAF sensor is used for measuring EGR performance as well as fuelling strategy. When it's unplugged on a Td4 the ecu runs in default mode and if no difference then that to me indicates your MAF is working well

This looks slam dunk to be the fuel pressure sensor loom (YMQ503320) or the HP fuel pump pressure regulator O rings - probably the latter as its consistent and not random.

after spending loads of cash on things that were not at fault it turned out to be the o ring split on the high pressure regulator on the pump...£11.27 off ebay ////can be done without taking the pump off...about an hour or so for me.

xamtex said:

after spending loads of cash on things that were not at fault it turned out to be the o ring split on the high pressure regulator on the pump...£11.27 off ebay ////can be done without taking the pump off...about an hour or so for me.

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So the lesson learned is to start with the simple stuff first before you go rebuilding the car from scratch . Glad you got it sorted

Madmustang said:

So the lesson learned is to start with the simple stuff first before you go rebuilding the car from scratch . Glad you got it sorted

Click to expand...

Another lesson is the O rings kit is available at £5.99 too
At least it's running again, all down to the pesky little O rings.

Nodge68 said:

Another lesson is the O rings kit is available at £5.99 too
At least it's running again, all down to the pesky little O rings.

Click to expand...

For completeness of the thread can you link to a supplier or provide the part number?

Madmustang said:

For completeness of the thread can you link to a supplier or provide the part number?

Click to expand...

http://www.ebay.co.uk/itm/Common-Ra...-0281002480-/332113306745?hash=item4d537ee479

This fits the Bosch 0281002480 pressure regulator.

Can someone say how you fit the stiff (nylon/Teflon) o-ring onto the high pressure regulator?

comeinhandy said:

Can someone say how you fit the stiff (nylon/Teflon) o-ring onto the high pressure regulator?

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If it isn't damaged, then I just replace the rubber one.

Nodge68 said:

If it isn't damaged, then I just replace the rubber one.

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Found the answer having tried it, They have a small split to aid fitting, so quite easy. The nylon washer was warn away on one side causing high pressure loss as the rubber o ring tilted over. With new seals HP sensor reading is back to all good at ~2 volts at 3000 rpm (1.28v at idle).