BMW experts help please

[david87M3]

Evening.
what can cause a lean running condition on an e39 523 with the M52tu engine (1999 year car)
I get a pre ignition rattle/ping noise under load (going up hill)
Spark plugs look white in colour on electrode's (4 prongs that go to tip)
Intake gaskets have been done (helped a bit) both pre cat o2 sensors replaced.
the crank case vent valve has been replaced as there was no vacuum at the fuel pressure reg hose. This has been done 2 times and still no vac.
could it be a failing fuel pump?
car runns great when cold.
also has its days when it feels lacking in power

Thanks

[ec523]

Hi you need to speak to these guys they are the best in London.
www.bwautorepairs.co.uk/

[david87M3]

thanks will give them a call

Dave