Boot pressure invalid

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timh1970

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Ok, so fault of the week this week is "Boost Pressure Invalid" followed by a drop in power. This only happens at high revs when the kickdown kicks in going up a steep motorway hill. As soon as the fault occurs there is an instant loss of power.

I have changed the MAP sensor and the pipes from the turbo to the inlet manifold all seem ok.

Any ideas once again would be very much appreciated.

2.5 DSE BTW
 
timh1970 said:
Ok, so fault of the week this week is "Boost Pressure Invalid" followed by a drop in power. This only happens at high revs when the kickdown kicks in going up a steep motorway hill. As soon as the fault occurs there is an instant loss of power.

I have changed the MAP sensor and the pipes from the turbo to the inlet manifold all seem ok.

Any ideas once again would be very much appreciated.

2.5 DSE BTW
Click to expand...
Check the spigot on the manifold for the MAP is not blocked, also if it has EGR, check that is not coked up.
Boost control is mechanical, could also be that is stuck.
 
Today I took the turbo off, disconnected the actuator pipe and tried moving the actuator manually.

Having left it on the bench for a while I notices oil p'sing out of the pipe that was attached to the actuator so I guess that the actuator being full of oil stopped it performing as it should.

It seems the seals have gone on the turbo but hey, it's only money.

Has anybody had experience with these cores that you can buy off ebay

Turbo Turbocharger CHRA Cartridge Land-Rover Range Rover 2,5 TDI (1994-2003) | eBay

I don't want to put a second hand turbo on it and know that you cannot really recondition them without equipment to balance them so wondered what everybody thought of these as an alternative.
 
When you had diag on it what unit did you use. Did you not read the boost pressures and note them? It is normal for there to be some oil in output side on the M51. Have you tested the actuator with air to see what pressure it is opening at? Not used the cores but if you get one make sure it is well lubed up with oil before you start engine.
 
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Yes I have tested it with air and it does appear to work without much resistance but by the time I had tested it the oil had run out.

The boost pressure was high when it went invalid (I though I saw it at 240something, but it went invalid pretty quick and I had one eye on the road so can't be certain). I only serviced it around 3000 miles ago at the most and it is now half way between the 2 marks. There is a lot of oil under the outlet of the intercooler and I literally poured it out of the actuator body when I tipped it up.

I had one go on me a few years ago on a renault master: The turbo seal went and the engine drank its own oil which killed it 37,000 miles into its life.
 
timh1970 said:
Yes I have tested it with air and it does appear to work without much resistance but by the time I had tested it the oil had run out.

The boost pressure was high when it went invalid (I though I saw it at 240something, but it went invalid pretty quick and I had one eye on the road so can't be certain). I only serviced it around 3000 miles ago at the most and it is now half way between the 2 marks. There is a lot of oil under the outlet of the intercooler and I literally poured it out of the actuator body when I tipped it up.

I had one go on me a few years ago on a renault master: The turbo seal went and the engine drank its own oil which killed it 37,000 miles into its life.
Click to expand...

Yes that is something to consider, if in doubt change the turbo. A new core would be reasonably easy to fit but you also need to know that the waste gate opens at the correct pressure. The oil in the actuator may have been damping it's effective opening pressure.
 
wammers said:
Yes that is something to consider, if in doubt change the turbo. A new core would be reasonably easy to fit but you also need to know that the waste gate opens at the correct pressure. The oil in the actuator may have been damping it's effective opening pressure.
Click to expand...

Good point. I might see if I can find somebody who has got a used one that isn't full of oil and just replace it because I don't think you can buy them on their own.

I was fairly unscientific when I tested it (I blew an airline past the pipe). Do you know what pressure is supposed to actuate it?
 
timh1970 said:
Good point. I might see if I can find somebody who has got a used one that isn't full of oil and just replace it because I don't think you can buy them on their own.

I was fairly unscientific when I tested it (I blew an airline past the pipe). Do you know what pressure is supposed to actuate it?
Click to expand...

First thing to do is check that MAP sensor is reading correctly, at idle boost pressure should equal ambient. Boost pressure checked at 3000 and 4000 RPM with engine loaded should be a minimum 950 Mbar 13.78 PSI, maximum 1150 Mbar 16.67 PSI. At 4000 RPM the waste gate should be open and the max pressure should not be exceeded. Usually done on a long hill in a mid range gear, Maintain RPM at 3000 RPM and brake to load engine giving a 200 RPM or so drop then take reading. You have to T a pressure gauge into MAP pressure pipe and run it into the cab.
 
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