Evening boys and girls,
I have made my introductions in the other section so now it's time to open myself up to the wrath of the forum. I've searched the forum already but nothing quite describes the issues I'm having.

My td4 runs a bit rough at idle with a rattle at approx 1200 rpm when accelerating. I can hear the turbo spooling up and performance is acceptable with increasing rpm but low down below 2500 it's not so good.

I have already changed out the pcv with the BMW part, no obvious leaks on hoses etc. I also checked and cleaned the EGR valve (not too dirty for 50k), tried disconnecting the vac line but no difference noted. Also disconnected the maf but performance worse if anything so I'm just after some pointers and checks on my thoughts for the way forward.

Is it correct to assume that performance ok at higher revs means that turbo, actuator, solenoid and turbo filter must be ok?
I'm thinking of the fuel pressure sensor, map sensor, injector or fuel filter/pump.

Apologies for the extended post.
Let the insults begin!!!

from another post :

Is that the best way to check for a faulty injector i.e. pull off each electrical connector and listen for change in engine sound? Will this bring on a fault light, will it reset automatically?

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i think the way to find a faulty injector .. is to do the 'leak back test'
( do a site search .. be a few threads about it )

there might be other ways .. i don't know ..
but maybe someone will chime in 'n tell all
( or .. keep site searching .. some info be sure to be there )

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My td4 runs a bit rough at idle with a rattle at approx 1200 rpm when accelerating. I can hear the turbo spooling up and performance is acceptable with increasing rpm but low down below 2500 it's not so good.

Click to expand...

what sort of 'rattle' is it .. ?
i.e. combustion noise .. or some component rattling in sympathy to engine vibes
asking 'cause at 1200 rpm seems to be a peak vibration point on mine ..
'n cause anything loose in the cab to 'buzz' or 'rattle' ..

so .. it ain't the MAF ? .. as that's normaly the culprit for low power under 2500 rpm

Is it correct to assume that performance ok at higher revs means that turbo, actuator, solenoid and turbo filter must be ok?

Click to expand...

i would have thought so ..

I'm thinking of the fuel pressure sensor, map sensor, injector or fuel filter/pump.

Click to expand...

maybe fuel pressure sensor, map sensor ? .. ..
dunno about injector if like you say there be plenty of power above 2500 ..
any smoke issues ??

maybe worth checking the plug connectors to the fuel rail sensor ..
'cause at low rpm .. low rail pressure .. the voltage from the sensor back to the ecu
is really low .. so any hint of dirt or corrosion would cut the voltage signal ..
be like 5v in .. then anything between 0.5v to 5v ..
and the td4 has a known water ingress problem to that area .. that connector in particular ..

scroll down in this .pdf .. until you see the 'fuel rail pressure sensor'
http://www.yildiz.edu.tr/~oisin/Dersler/Dersnotlari/0653611/dinjection.pdf

more info here ( if you've not already seen the page )
ROVER 75 MGZT ENGINE FAULT FINDING

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a bit more td4 info here .. ( but not the variable vane turbo )
http://www.rover-club.net/graphics/manuals/16/m47r_diesel.pdf

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not sure what else to suggest re low power at sub 2500 rpm ..
( given above that be ok .. and you rekon the maf sensor is ok as well )

'n thought i'd bump the thread in anycase someone else might have an idea or two ..