I have bought a 2011 Overfinch 4.4 tdv8, problem is when cold ,its difficult to start and will not rev up until after about 5 mins.
The revs only build up gradually. It has a EGR delete ,the codes a P0088 high fuel pressure.
Changed fuel pressure sensor, cam sensor ,fuel pressure regulator,
once in a while it will drive amazing then cut out or just not start straight after, it sounds like something is blocked to me, should the intercooler actuator on the nearside lower part on the engine valve open and close when starting or turning off, the vacuum lever seams stiff to move ,any help welcome please. Mercedes AMG w207
E class Cabriolet
Overfinch L322 4.4 tdv8
1987 sierra rs cosworth 3 door white.
1985 escort rs turbo series one.
1992 sierra sapphire 4x4 cosworth red
1993 sierra sapphire cosworth 4x4 silver
1993 sierra sapphire cosworth 4x4 white
1995 ducati 916sp.

Do you know if the fuel filter has been changed? When I changed my air filters I forgot to plug in one of the MAF sensors and it ran similar to yours. One could be faulty. Obviously check the four hoses on the plenum chamber.

The secondary turbo changeover/isolation valve only opens under higher engine load and not until around 2500 rpm. However its lever should be able to be moved in the direction of moving the rod into the vacuum chamber although the spring is quite strong. Vacuum provided to the chamber by bypassing or energising the solenoid valve (one of the solenoids at the top front of the engine) at idle will open the valve.
I doubt that the valve is the cause of the poor performance issue.

Tried MAF sensors and MAP sensor still the same, looks like poss High Pressure Fuel Pump. Mercedes AMG w207
E class Cabriolet
Overfinch L322 4.4 tdv8
1987 sierra rs cosworth 3 door white.
1985 escort rs turbo series one.
1992 sierra sapphire 4x4 cosworth red
1993 sierra sapphire cosworth 4x4 silver
1993 sierra sapphire cosworth 4x4 white
1995 ducati 916sp.

Presumably the fuel system has been bled.

Has the EGR system been taken out?

Yes the fuel System is bled, the egr has a blacking plate fitted. Mercedes AMG w207
E class Cabriolet
Overfinch L322 4.4 tdv8
1987 sierra rs cosworth 3 door white.
1985 escort rs turbo series one.
1992 sierra sapphire 4x4 cosworth red
1993 sierra sapphire cosworth 4x4 silver
1993 sierra sapphire cosworth 4x4 white
1995 ducati 916sp.

I’m assuming the EGRs are mapped out the engine management system too? I don’t believe you can blank them without issue, unless you do other things.

I’m no expert though. Never done it.

 2011 Range Rover Vogue SE 4.4 TDV8

Previous cars :
2003 Range Rover Vogue TD6
1999 Discovery Td5 ES
1995 BMW M5 3.8 6 speed
1992 Range Rover 3.9 Efi Vogue
1992 BMW M5 3.8
1988 BMW 735i SE
1989 Ford Sierra XR4x4 2.9i
1981 Ford Fiesta Supersport

I have been told the EGR was deleted from the map ,but im still getting a EGR fault showing. Mercedes AMG w207
E class Cabriolet
Overfinch L322 4.4 tdv8
1987 sierra rs cosworth 3 door white.
1985 escort rs turbo series one.
1992 sierra sapphire 4x4 cosworth red
1993 sierra sapphire cosworth 4x4 silver
1993 sierra sapphire cosworth 4x4 white
1995 ducati 916sp.

I have been told the EGR was deleted from the map ,but im still getting a EGR fault showing. Mercedes AMG w207
E class Cabriolet
Overfinch L322 4.4 tdv8
1987 sierra rs cosworth 3 door white.
1985 escort rs turbo series one.
1992 sierra sapphire 4x4 cosworth red
1993 sierra sapphire cosworth 4x4 silver
1993 sierra sapphire cosworth 4x4 white
1995 ducati 916sp.

I know they aren’t the easiest things to get to, but what about removing the blanking plates. If it’s mapped out the EGRs won’t open anyway.... has it always done this? Is there anything else changed recently?

Hope you get it sorted. Folk on here know more about EGRs than I do....

 2011 Range Rover Vogue SE 4.4 TDV8

Previous cars :
2003 Range Rover Vogue TD6
1999 Discovery Td5 ES
1995 BMW M5 3.8 6 speed
1992 Range Rover 3.9 Efi Vogue
1992 BMW M5 3.8
1988 BMW 735i SE
1989 Ford Sierra XR4x4 2.9i
1981 Ford Fiesta Supersport

I'd personally get it back to standard and have the egr blanking removed ttoally Gone to a good home: 2011 4.4 TDV8 Vogue SE Buckingham Blue with Ivory and clear glass = "Rory"
2025MY Defender D350 90 in Silicon Silver on coils
1974 Series 3 Lightweight = "Millie"
Many, many other Landies over the years
My preferred specialist: www.glenrands.co.uk
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Would a failing high pressure fuel pump not give me these Symptoms. Mercedes AMG w207
E class Cabriolet
Overfinch L322 4.4 tdv8
1987 sierra rs cosworth 3 door white.
1985 escort rs turbo series one.
1992 sierra sapphire 4x4 cosworth red
1993 sierra sapphire cosworth 4x4 silver
1993 sierra sapphire cosworth 4x4 white
1995 ducati 916sp.

I though I read somewhere that the egr can’t be removed on the 4.4s

+1 for DrRob's suggestion, trying to find a fault on something that has been "upgraded" by a previous owner is always going to be a ball ache